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2018 Volume Issue 5
2018, 0(5): 553-558
doi: 10.11777/j.issn1000-3304.2018.18070
Abstract:
A single-stranded DNA with adenosine triphosphate (ATP) aptamer sequence and a single-stranded DNA with cohesive end were designed for the formation of linear DNA hydrogel. First, a double-stranded DNA monomer was formed by the hybridization of sticky ends. Then this monomer self-assembled to form a long linear DNA polymer and further form a DNA hydrogel by physically cross-linking. The formation of the hydrogel was characterized by rheological tests and the transition from the gel state to the solution state was observed by stress scanning. Using methylene blue (MB) as a marker, the responsive dynamics of the DNA hydrogel to ATP was characterized by UV absorption spectroscopy. Within 15 min after the addition of ATP, the absorbance of the DNA hydrogel at 664 nm rose rapidly and reached a plateau, indicating that the DNA hydrogel can respond quickly to ATP. Moreover, the absorbance of the DNA hydrogel at 664 nm has a good linear correlation with ATP concentration. For comparison, ATP, thymidine triphosphate (TTP), cytidine triphosphate (CTP) and guanosine triphosphate (GTP) were added to the DNA hydrogel, respectively. The UV absorption spectrum test showed that only the ATP-containing DNA hydrogel was depolymerized and MB was released, indicating that the DNA hydrogel has good stability and its response to ATP was specific.
A single-stranded DNA with adenosine triphosphate (ATP) aptamer sequence and a single-stranded DNA with cohesive end were designed for the formation of linear DNA hydrogel. First, a double-stranded DNA monomer was formed by the hybridization of sticky ends. Then this monomer self-assembled to form a long linear DNA polymer and further form a DNA hydrogel by physically cross-linking. The formation of the hydrogel was characterized by rheological tests and the transition from the gel state to the solution state was observed by stress scanning. Using methylene blue (MB) as a marker, the responsive dynamics of the DNA hydrogel to ATP was characterized by UV absorption spectroscopy. Within 15 min after the addition of ATP, the absorbance of the DNA hydrogel at 664 nm rose rapidly and reached a plateau, indicating that the DNA hydrogel can respond quickly to ATP. Moreover, the absorbance of the DNA hydrogel at 664 nm has a good linear correlation with ATP concentration. For comparison, ATP, thymidine triphosphate (TTP), cytidine triphosphate (CTP) and guanosine triphosphate (GTP) were added to the DNA hydrogel, respectively. The UV absorption spectrum test showed that only the ATP-containing DNA hydrogel was depolymerized and MB was released, indicating that the DNA hydrogel has good stability and its response to ATP was specific.
2018, 0(5): 559-570
doi: 10.11777/j.issn1000-3304.2017.17298
Abstract:
As new emerged polymer materials, nanoporous organic polymers (NOPs), derived completely from light elements, are featured by high surface areas, low skeleton densities, and good chemical and thermal stabilities, which have led to numerous potential applications in heterogeneous catalysis, gas storage, and separation. Furthermore, their versatile synthetic methodology, controllable pore structure and easy modification significantly accelerate their development. Recently, the applications of NOPs targeted for organic electronic devices and solid state sensors have drawn increasing attention. The study of NOP-based electrochemical sensor technologies has become a very active and robust research area, and is expected to provide high-performance technologies for electrode materials, electrocatalytic carrier, and electrochemical detection, etc. One potential advantage of these materials is derived from their porous robust frameworks with high accessible surface areas, which enable structural preservation and efficient metal uptake and diffusion. However, the weak electron transport and wettability of NOPs somewhat limit their practical application in electrochemistry. In response, novel strategies have been developed to enhance their conductivity and wettability, including the incorporation of heteroatoms, extending of the skeleton conjugation, and the introduction of metal sites into the porous networks. Especially, the introduction of heteroatoms into the electrode materials is the mostly utilized technology, because it not only enables the increase in conductivity, wettablity and electroactive surface area of the electrodes, but also endows the electrodes with high pseudocapacitance. Furthermore, pore-size engineering, i.e., enhancing microporosity and constructing hierarchical structure, is crucial to improve the electrochemical performance. Hierarchically porous materials used as electrode matrices appear to be much more favorable for mass loading and ion diffusion or transport, endowing them with technological importance for applications in energy storage and sensor applications. This study summarizes recent research progress of NOPs in electrochemical applications, focuses on rational design, pore engineering and the structure-electrochemical property relationship, and also prospects their future development.
As new emerged polymer materials, nanoporous organic polymers (NOPs), derived completely from light elements, are featured by high surface areas, low skeleton densities, and good chemical and thermal stabilities, which have led to numerous potential applications in heterogeneous catalysis, gas storage, and separation. Furthermore, their versatile synthetic methodology, controllable pore structure and easy modification significantly accelerate their development. Recently, the applications of NOPs targeted for organic electronic devices and solid state sensors have drawn increasing attention. The study of NOP-based electrochemical sensor technologies has become a very active and robust research area, and is expected to provide high-performance technologies for electrode materials, electrocatalytic carrier, and electrochemical detection, etc. One potential advantage of these materials is derived from their porous robust frameworks with high accessible surface areas, which enable structural preservation and efficient metal uptake and diffusion. However, the weak electron transport and wettability of NOPs somewhat limit their practical application in electrochemistry. In response, novel strategies have been developed to enhance their conductivity and wettability, including the incorporation of heteroatoms, extending of the skeleton conjugation, and the introduction of metal sites into the porous networks. Especially, the introduction of heteroatoms into the electrode materials is the mostly utilized technology, because it not only enables the increase in conductivity, wettablity and electroactive surface area of the electrodes, but also endows the electrodes with high pseudocapacitance. Furthermore, pore-size engineering, i.e., enhancing microporosity and constructing hierarchical structure, is crucial to improve the electrochemical performance. Hierarchically porous materials used as electrode matrices appear to be much more favorable for mass loading and ion diffusion or transport, endowing them with technological importance for applications in energy storage and sensor applications. This study summarizes recent research progress of NOPs in electrochemical applications, focuses on rational design, pore engineering and the structure-electrochemical property relationship, and also prospects their future development.
2018, 0(5): 571-580
doi: 10.11777/j.issn1000-3304.2017.17178
Abstract:
Surface polymer brushes have been extensively studied to modify the surface properties of substrates and to implement multifunctionality. Compared to comb type brushes, hyperbranched-structure polymer brushes show significant advantages in thermal stability, compatibility and functionalization potential. The preparation study of surface hyperbranched polymer brushes is fundamental to explode polymer brushes applications. Here, laser-mediated surface-initiated atom transfer radical polymerization (SI-ATRP) is firstly introduced to conduct self-condensing polymerization, with 2-bromoisobutyrate ester of oligo (ethylene glycol) methacrylate (OEGMA-Br) as AB*-type inimer and Ir(ppy)3 as the photo-redox catalyst, to prepare hyperbranched poly(ethylene glycol)(PEG) brushes on a silicon substrate. Based on the discussion on the mechanism of OEGMA-Br inimer self-condensing polymerization on solid-liquid interface and at surface solution on silicon surface, five microstructures are proposed for the constitution of the hyperbranched PEG brushes and the corresponding signals are further confirmed by 1H-NMR spectra analysis. X-ray photoelectron spectroscopy (XPS) characterization is conducted to investigate the chemical composition of hyperbranched PEG brushes. The high resolution C1s and Br3d spectra indicate the preservation of surface bromine density on hyperbranched PEG brushes in comparison to initiator surface on silicon substrate, implying the hyperbranched microstructure and high active site densities. Then, the thickness of hyperbranched PEG brushes corresponding to different inimer concentrations is investigated by ellipsometry, which indicates an increase first in the thickness and a subsequant decrease trend as the inimer concentration increased. A competitive mechanism for the surface polymerization is proposed to depict the growth of the hyperbranched PEG brushes on a silicon substrate, which refers to a competition between the solid-liquid interface polymerization and the surface solution polymerization. An increase of inimer concentration would promote the self-condensing polymerization of the inimer in solution, which consequently inhibits the solid-liquid interface polymerization and is unfavorable to the hyperbranched PEG brushes growth. Furthermore, laser confocal microscopy observation of the absorption of 5-isothiocyanatofluorescein (FITC) labeled bovine serum albumin (BSA) on hyperbranched PEG brushes micropatterns proves the significant anti-fouling property. The research extends the application of photo-catalyzed SI-ATRP in the preparation of surface hyperbranched-structure polymer brushes, and provides fundamental technical support to expand the applications of the hyperbranched PEG brushes in drug transport, biosensing and high-throughput cell screening.
Surface polymer brushes have been extensively studied to modify the surface properties of substrates and to implement multifunctionality. Compared to comb type brushes, hyperbranched-structure polymer brushes show significant advantages in thermal stability, compatibility and functionalization potential. The preparation study of surface hyperbranched polymer brushes is fundamental to explode polymer brushes applications. Here, laser-mediated surface-initiated atom transfer radical polymerization (SI-ATRP) is firstly introduced to conduct self-condensing polymerization, with 2-bromoisobutyrate ester of oligo (ethylene glycol) methacrylate (OEGMA-Br) as AB*-type inimer and Ir(ppy)3 as the photo-redox catalyst, to prepare hyperbranched poly(ethylene glycol)(PEG) brushes on a silicon substrate. Based on the discussion on the mechanism of OEGMA-Br inimer self-condensing polymerization on solid-liquid interface and at surface solution on silicon surface, five microstructures are proposed for the constitution of the hyperbranched PEG brushes and the corresponding signals are further confirmed by 1H-NMR spectra analysis. X-ray photoelectron spectroscopy (XPS) characterization is conducted to investigate the chemical composition of hyperbranched PEG brushes. The high resolution C1s and Br3d spectra indicate the preservation of surface bromine density on hyperbranched PEG brushes in comparison to initiator surface on silicon substrate, implying the hyperbranched microstructure and high active site densities. Then, the thickness of hyperbranched PEG brushes corresponding to different inimer concentrations is investigated by ellipsometry, which indicates an increase first in the thickness and a subsequant decrease trend as the inimer concentration increased. A competitive mechanism for the surface polymerization is proposed to depict the growth of the hyperbranched PEG brushes on a silicon substrate, which refers to a competition between the solid-liquid interface polymerization and the surface solution polymerization. An increase of inimer concentration would promote the self-condensing polymerization of the inimer in solution, which consequently inhibits the solid-liquid interface polymerization and is unfavorable to the hyperbranched PEG brushes growth. Furthermore, laser confocal microscopy observation of the absorption of 5-isothiocyanatofluorescein (FITC) labeled bovine serum albumin (BSA) on hyperbranched PEG brushes micropatterns proves the significant anti-fouling property. The research extends the application of photo-catalyzed SI-ATRP in the preparation of surface hyperbranched-structure polymer brushes, and provides fundamental technical support to expand the applications of the hyperbranched PEG brushes in drug transport, biosensing and high-throughput cell screening.
2018, 0(5): 581-587
doi: 10.11777/j.issn1000-3004.2017.17211
Abstract:
High temperature solution copolymerization of 4,4′-sulfonyl-bis(trifluorovinyloxy)biphenyl (DTS) and 4,4 ′-bis(trifluorovinyloxy)biphenyl (DTB) were carried out in diphenyl ether as the solvent. A series of perfluorocyclobutyl copoly(aryl ether)s containing biphenyl and sulfonyl moieties (PFCB-S-BP) were prepared via thermal [2π + 2π] cycloaddition polymerization by controlling the ratio of DTS to DTB. PFCB-S-BP was synthesized when the ratio of DTS to DTB ranged from 3/7 to 7/3. Molecular weight and its distribution of PFCB-S-BP were measured by gel permeation chromatography (GPC). The GPC curves showed a narrow and unimodal elution peak. The number-average molecular weight of PFCB-S-BP was larger than 1.4 × 104, with a narrow molecular weight distribution ranging from 1.4 to 1.6. The chemical structures was characterized by Fourier transform infrared spectroscopy Fourier transform infrared spectroscopy (FTIR), hydrogen nuclear magnetic resonance (1H-NMR) and fluorine nuclear magnetic resonance (19F-NMR). The characteristic signal of trifluorovinyl ether group of monomers at 1824 cm−1 disappeared in Fourier transform infrared spectroscopy (FTIR) spectra of PFCB-S-BP and the strong perfluorocyclobutyl group characteristic peak at 957 cm−1 appeared. The intensities of sulfonyl group characteristic absorption peaks at 1100 and 1315 cm−1 increased with the increase in the ratio of DTS to DTB. From 1H-NMR of PFCB-S-BP, the signal at 7.9 was assigned to the protons of benzene ring adjacent to sulfonyl group. The intensity of the signal increased with an increase in the ratio of DTS to DTB. For 19F-NMR of PFCB-S-BP, the multiple peaks ranging from −127 to −134 were ascribed to the cis- and trans-substituted PFCB rings. These results indicated that DTS copolymerized with DTB, and PFCB-S-BP copolymers were successfully synthesized. The thermal property and solubility of PFCB-S-BP were also tested. Tg of PFCB-S-BP increased slightly from 146 °C to 153 °C with an increase in the ratio of DTS to DTB from 3/7 to 7/3. The decomposition temperature for 5% weight loss of PFCB-S-BP was above 470 °C. These results showed that PFCB-S-BP exhibited high thermal stability and was soluble in common organic solvents such as N-methyl-2-pyrrolidinone, N,N-dimethylacetamide and chloroform.
High temperature solution copolymerization of 4,4′-sulfonyl-bis(trifluorovinyloxy)biphenyl (DTS) and 4,4 ′-bis(trifluorovinyloxy)biphenyl (DTB) were carried out in diphenyl ether as the solvent. A series of perfluorocyclobutyl copoly(aryl ether)s containing biphenyl and sulfonyl moieties (PFCB-S-BP) were prepared via thermal [2π + 2π] cycloaddition polymerization by controlling the ratio of DTS to DTB. PFCB-S-BP was synthesized when the ratio of DTS to DTB ranged from 3/7 to 7/3. Molecular weight and its distribution of PFCB-S-BP were measured by gel permeation chromatography (GPC). The GPC curves showed a narrow and unimodal elution peak. The number-average molecular weight of PFCB-S-BP was larger than 1.4 × 104, with a narrow molecular weight distribution ranging from 1.4 to 1.6. The chemical structures was characterized by Fourier transform infrared spectroscopy Fourier transform infrared spectroscopy (FTIR), hydrogen nuclear magnetic resonance (1H-NMR) and fluorine nuclear magnetic resonance (19F-NMR). The characteristic signal of trifluorovinyl ether group of monomers at 1824 cm−1 disappeared in Fourier transform infrared spectroscopy (FTIR) spectra of PFCB-S-BP and the strong perfluorocyclobutyl group characteristic peak at 957 cm−1 appeared. The intensities of sulfonyl group characteristic absorption peaks at 1100 and 1315 cm−1 increased with the increase in the ratio of DTS to DTB. From 1H-NMR of PFCB-S-BP, the signal at 7.9 was assigned to the protons of benzene ring adjacent to sulfonyl group. The intensity of the signal increased with an increase in the ratio of DTS to DTB. For 19F-NMR of PFCB-S-BP, the multiple peaks ranging from −127 to −134 were ascribed to the cis- and trans-substituted PFCB rings. These results indicated that DTS copolymerized with DTB, and PFCB-S-BP copolymers were successfully synthesized. The thermal property and solubility of PFCB-S-BP were also tested. Tg of PFCB-S-BP increased slightly from 146 °C to 153 °C with an increase in the ratio of DTS to DTB from 3/7 to 7/3. The decomposition temperature for 5% weight loss of PFCB-S-BP was above 470 °C. These results showed that PFCB-S-BP exhibited high thermal stability and was soluble in common organic solvents such as N-methyl-2-pyrrolidinone, N,N-dimethylacetamide and chloroform.
2018, 5(5): 588-597
doi: 10.11777/j.issn1000-3304.2017.17248
Abstract:
The preparation of LCB-PP using symmetrical multifunctional vinyl monomers as grafting monomers presents a difficulty to efficiently control side reactions, such as peroxide-initiated chain scission and branching monomer-assisted crosslinking. In this work, we synthesized two nonsymmetrical divinyl monomers, butenyl acrylate (BAC), and 1-(but-3-enyloxy)methyl-4-vinylbenzene (BMVB) containing two carbon-carbon double bonds with different reactivity ratios. These two monomers were used in melt radical reaction of PP to prepare LCB-PP. High-temperature GPC (HT-GPC) coupled with triple detectors, 1H-NMR and rheometer were used to characterize the microstructure and melt properties of the resultant LCB-PP. The results showed that the two monomers had double function in mediating radical reaction,i.e. stabilizing macroradicals and promoting branching reaction. Owing to a much higher reactivity ratio of the high reactive vinyl to the low reactive vinyl in the BMVB monomer, the higher reactive double-bond of BMVB preferentially reacted with macroradicals to stabilize PP macroradicals quickly, while the lower reactive double-bond later reacted with macroradicals to avoid the formation of hyper-branched or even crosslinked structure and to promote therefore the formation of long chain branched structure. Thus, compared to BAC, using BMVB as a grafting monomer led to less degradation of PP and helped to the formation of more uniformly distributed LCB structure on the PP backbone. These results demonstrate that the reactivity ratio of double-bonds in a grafting monomer to macroradicals is a key factor to control melt reaction. It is believed that further optimizing chemical structure of grafting monomer with nonsymmetrical vinyl groups, especially the reactivity ratio of double-bonds in branching monomer, will be beneficial to mediating this melt reaction.
The preparation of LCB-PP using symmetrical multifunctional vinyl monomers as grafting monomers presents a difficulty to efficiently control side reactions, such as peroxide-initiated chain scission and branching monomer-assisted crosslinking. In this work, we synthesized two nonsymmetrical divinyl monomers, butenyl acrylate (BAC), and 1-(but-3-enyloxy)methyl-4-vinylbenzene (BMVB) containing two carbon-carbon double bonds with different reactivity ratios. These two monomers were used in melt radical reaction of PP to prepare LCB-PP. High-temperature GPC (HT-GPC) coupled with triple detectors, 1H-NMR and rheometer were used to characterize the microstructure and melt properties of the resultant LCB-PP. The results showed that the two monomers had double function in mediating radical reaction,i.e. stabilizing macroradicals and promoting branching reaction. Owing to a much higher reactivity ratio of the high reactive vinyl to the low reactive vinyl in the BMVB monomer, the higher reactive double-bond of BMVB preferentially reacted with macroradicals to stabilize PP macroradicals quickly, while the lower reactive double-bond later reacted with macroradicals to avoid the formation of hyper-branched or even crosslinked structure and to promote therefore the formation of long chain branched structure. Thus, compared to BAC, using BMVB as a grafting monomer led to less degradation of PP and helped to the formation of more uniformly distributed LCB structure on the PP backbone. These results demonstrate that the reactivity ratio of double-bonds in a grafting monomer to macroradicals is a key factor to control melt reaction. It is believed that further optimizing chemical structure of grafting monomer with nonsymmetrical vinyl groups, especially the reactivity ratio of double-bonds in branching monomer, will be beneficial to mediating this melt reaction.
2018, 0(5): 598-606
doi: 10.11777/j.issn1000-3304.2017.17197
Abstract:
Poly(L-lactic acid) (PLLA) is a biodegradable and biocompatible material used in many fields, such as packaging, textile and drug delivery. The low crystallization rate and poor toughness are two major drawbacks for its processing and high-performance applications. In this study, poly(D-lactic acid)-polyethylene glycol (PEG)-poly(D-lactic acid) triblock copolymers (PDLA-b-PEG-b-PDLA) were used to modify the structure and property of PLLA. PLLA/PDLA-b-PEG-b-PDLA blends were prepared by melt blending, and their thermal and mechanical properties were systematically studied by thermal gravimetric analysis (TGA), differential scanning calorimetry (DSC) and temperature-variable tensile tests. To understand the structure evolution, the crystallization behavior of the blends during stretching was investigated by in situ wide angle X-ray scattering (WAXS). The results showed that the addition of PDLA-b-PEG-b-PDLA had no detrimental effect on the thermal stability of PLLA. By virtue of the nucleation capacity of the stereo-complex crystals formed between PLLA and PDLA chains, the crystallization rate of the α crystals of the PLLA matrix was improved remarkably compared with that of pure PLLA. When stretched at room temperature (30 °C), the modified PLLA samples displayed brittle fracture. With the stretching temperature increased to 50 °C, both PLLA and PLLA/PDLA-b-PEG-b-PDLA (95/5) exhibited brittle fracture. However, the blends showed clear yielding and ductile deformation with an elongation at break as high as 200% when the content of the triblock copolymer was above 5%. With the stretching temperature further increased to 80 °C, the crystallization of α crystals in the PLLA/ PDLA-b-PEG-b-PDLA blends was significantly enhanced during the stretching process. The critical strain, where α crystals appeared in the blend, decreased from 400% in pure PLLA to less than 50%. The stereo-complex crystallites had no change during the stretching process. The above results indicated that the triblock copolymer consisting of PDLA and PEG chains was an excellent candidate as PLLA modifier with dual effects of promoting crystallization and improving toughness.
Poly(L-lactic acid) (PLLA) is a biodegradable and biocompatible material used in many fields, such as packaging, textile and drug delivery. The low crystallization rate and poor toughness are two major drawbacks for its processing and high-performance applications. In this study, poly(D-lactic acid)-polyethylene glycol (PEG)-poly(D-lactic acid) triblock copolymers (PDLA-b-PEG-b-PDLA) were used to modify the structure and property of PLLA. PLLA/PDLA-b-PEG-b-PDLA blends were prepared by melt blending, and their thermal and mechanical properties were systematically studied by thermal gravimetric analysis (TGA), differential scanning calorimetry (DSC) and temperature-variable tensile tests. To understand the structure evolution, the crystallization behavior of the blends during stretching was investigated by in situ wide angle X-ray scattering (WAXS). The results showed that the addition of PDLA-b-PEG-b-PDLA had no detrimental effect on the thermal stability of PLLA. By virtue of the nucleation capacity of the stereo-complex crystals formed between PLLA and PDLA chains, the crystallization rate of the α crystals of the PLLA matrix was improved remarkably compared with that of pure PLLA. When stretched at room temperature (30 °C), the modified PLLA samples displayed brittle fracture. With the stretching temperature increased to 50 °C, both PLLA and PLLA/PDLA-b-PEG-b-PDLA (95/5) exhibited brittle fracture. However, the blends showed clear yielding and ductile deformation with an elongation at break as high as 200% when the content of the triblock copolymer was above 5%. With the stretching temperature further increased to 80 °C, the crystallization of α crystals in the PLLA/ PDLA-b-PEG-b-PDLA blends was significantly enhanced during the stretching process. The critical strain, where α crystals appeared in the blend, decreased from 400% in pure PLLA to less than 50%. The stereo-complex crystallites had no change during the stretching process. The above results indicated that the triblock copolymer consisting of PDLA and PEG chains was an excellent candidate as PLLA modifier with dual effects of promoting crystallization and improving toughness.
2018, 0(5): 607-616
doi: 10.11777/j.issn1000-3004.2017.17165
Abstract:
Compared with conventional reverse osmosis membrane (RO) materials, cellulose acetate (CA) reverse osmosis membranes have attracted considerable attention due to their unique chlorine resistance. However, β-glucose units in the cellulose backbone of CA molecule are vulnerable to erosion and degradation by aquatic microorganisms. To improve the antibacterial performance of cellulose triacetate reverse osmosis membrane, cellulose triacetate/chitosan blend reverse osmosis membrane (CTA/CS-RO) were designed and prepared with CS as the antibacterial agent by phase inversion. The homogeneous CTA solutions containning 20 g·L−1 CS in formic acid were casted with casting knife of 250 μm thickness and the asymmetrical CTA/CS-RO membranes were obtained after solvent evaporation, immersion precipitation process. The mass fractions of CS to CTA were selected to be 0.25%, 0.50%. 0.75%, 1.00% and 1.25%, respectively. The structure and performances of the obtained CTA/CS-RO membranes were characterized by various methods such as Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy, water contact angle and X-ray diffraction spectroscopy. The red shift of the characteristic peak of C―O―C in FTIR spectra indicated the presence of hydrogen bonding between CTA and CS. The characteristic peak of N1s in XPS spectra indicated the migration of CS to the membrane surface during phase inversion. The SEM images showed that membrane thickness decreased with increasing CS concentration. The addition of CS improved the hydrophilicity, water flux and mechanical properties of CTA/CS-ROs. When the mass fraction of CS to CTA was within 0.75%−1.00%, CTA/CS-ROs showed high salt rejection (R > 90%) without siginificant changes in elongation at break and crystallinity. The dynamic contact antibacterial test results indicated that CTA/CS-ROs showed inhibitory effect on E. coli and S. aureus, which was improved by increasing the content of CS. When the mass fraction of CS to CTA was within 0.75% − 1.00%, CTA/CS-ROs possessed higher inhibition rate against E. coli (65% − 72.5%) than S. aureus (16% − 51%) due to the electrostatic attraction between the positive CS and gram negative E. coli.
Compared with conventional reverse osmosis membrane (RO) materials, cellulose acetate (CA) reverse osmosis membranes have attracted considerable attention due to their unique chlorine resistance. However, β-glucose units in the cellulose backbone of CA molecule are vulnerable to erosion and degradation by aquatic microorganisms. To improve the antibacterial performance of cellulose triacetate reverse osmosis membrane, cellulose triacetate/chitosan blend reverse osmosis membrane (CTA/CS-RO) were designed and prepared with CS as the antibacterial agent by phase inversion. The homogeneous CTA solutions containning 20 g·L−1 CS in formic acid were casted with casting knife of 250 μm thickness and the asymmetrical CTA/CS-RO membranes were obtained after solvent evaporation, immersion precipitation process. The mass fractions of CS to CTA were selected to be 0.25%, 0.50%. 0.75%, 1.00% and 1.25%, respectively. The structure and performances of the obtained CTA/CS-RO membranes were characterized by various methods such as Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy, water contact angle and X-ray diffraction spectroscopy. The red shift of the characteristic peak of C―O―C in FTIR spectra indicated the presence of hydrogen bonding between CTA and CS. The characteristic peak of N1s in XPS spectra indicated the migration of CS to the membrane surface during phase inversion. The SEM images showed that membrane thickness decreased with increasing CS concentration. The addition of CS improved the hydrophilicity, water flux and mechanical properties of CTA/CS-ROs. When the mass fraction of CS to CTA was within 0.75%−1.00%, CTA/CS-ROs showed high salt rejection (R > 90%) without siginificant changes in elongation at break and crystallinity. The dynamic contact antibacterial test results indicated that CTA/CS-ROs showed inhibitory effect on E. coli and S. aureus, which was improved by increasing the content of CS. When the mass fraction of CS to CTA was within 0.75% − 1.00%, CTA/CS-ROs possessed higher inhibition rate against E. coli (65% − 72.5%) than S. aureus (16% − 51%) due to the electrostatic attraction between the positive CS and gram negative E. coli.
2018, 0(5): 617-623
doi: 10.11777/j.issn1000-3304.2017.17156
Abstract:
Black films play an important role in optics, electronics and other high-tech areas. This study aimed to produce a type of blend film that exhibits excellent mechanical properties and low transmittance. Blends of solutions were prepared by mechanical mixing a solution of poly(amic acid) (PAA) with that of polyacrylonitrile (PAN). Two types of PAA were synthesized, from BPDA/PDA/ODA and PMDA/ODA. The black films of PI/PAN were obtained by casting the solution blend onto a glass and followed by a thermal treatment. The blend films were withdrawn from the oven set at different temperatures. From these blend films, it was clearly observed that the color of the blend films changed from yellow to black. The effect of PAN content on their properties, structure and phase separation between PI and PAN were studied in detail. The blend films were characterized by Fourier transform infrared spectrometry, X-ray diffraction and universal materials tester. The results showed that imide rings were successfully formed and that the preoxidation of PAN was essentially complete. The mechanical strength decreased with increased PAN content, which was supported by the results from scanning electron microscopy (SEM) and UV-Vis light detector. The blend films were treated with a potassium hydroxide solution for 15 min. It was found that phase separation occurred between PI and PAN, revealed by observation of the surface and the cross-section morphology by SEM. With the increase in PAN content, the degree of phase separation also increased, which resulted in lower mechanical strength. This conclusion was also confirmed by the results of UV-Vis light detector. The transmittance of the blend films reduced because of the phase separation. In summary, the blend films of (BPDA/PDA/ODA)PI containing 10 wt% PAN and those of (PMDA/ODA)PI containing 20 wt% PAN exhibited excellent mechanical properties and low transmittance.
Black films play an important role in optics, electronics and other high-tech areas. This study aimed to produce a type of blend film that exhibits excellent mechanical properties and low transmittance. Blends of solutions were prepared by mechanical mixing a solution of poly(amic acid) (PAA) with that of polyacrylonitrile (PAN). Two types of PAA were synthesized, from BPDA/PDA/ODA and PMDA/ODA. The black films of PI/PAN were obtained by casting the solution blend onto a glass and followed by a thermal treatment. The blend films were withdrawn from the oven set at different temperatures. From these blend films, it was clearly observed that the color of the blend films changed from yellow to black. The effect of PAN content on their properties, structure and phase separation between PI and PAN were studied in detail. The blend films were characterized by Fourier transform infrared spectrometry, X-ray diffraction and universal materials tester. The results showed that imide rings were successfully formed and that the preoxidation of PAN was essentially complete. The mechanical strength decreased with increased PAN content, which was supported by the results from scanning electron microscopy (SEM) and UV-Vis light detector. The blend films were treated with a potassium hydroxide solution for 15 min. It was found that phase separation occurred between PI and PAN, revealed by observation of the surface and the cross-section morphology by SEM. With the increase in PAN content, the degree of phase separation also increased, which resulted in lower mechanical strength. This conclusion was also confirmed by the results of UV-Vis light detector. The transmittance of the blend films reduced because of the phase separation. In summary, the blend films of (BPDA/PDA/ODA)PI containing 10 wt% PAN and those of (PMDA/ODA)PI containing 20 wt% PAN exhibited excellent mechanical properties and low transmittance.
2018, 0(5): 624-631
doi: 10.11777/j.issn1000-3004.2017.17158
Abstract:
In order to promote the development of poly(vinylidene fluoride-co-hexafluoropropylene) [P(VDF-HFP)] fibers in industry, P(VDF-HFP) fibers were fabricated via single screw melt spinning machine. The fibers were drawn by thermal stretching process, and the polyvinylidene fluoride (PVDF) fibers were prepared as a reference. The crystal structure, melting behavior and mechanical properties of the fibers were investigated by X-ray diffraction, Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), thermogravimetric analysis (TG) and fiber strength test. The results revealed that the crystal morphology of fibers had α P(VDF-HFP) and β polymorphic forms, similar to PVDF fibers contributing to the regularly stacking of VDF moiety. The addition of HFP had an effect on crystallization, resulting in lower crystallinity in P(VDF-HFP) fibers. The increase of draw ratio not only facilitated the transition of crystalline phase from α to β phase, but also improved the crystallinity of the fibers. When the tensile strength was equal, a higher transformation of the crystalline form from α to β phase was observed in P(VDF-HFP) fibers than that in PVDF fibers, due to the steric effect in HFP structural unit. The thermal stability of the fibers was also improved and their crystallization consummated with stretching. The melting temperature and thermal decomposition temperature of P(VDF-HFP) fibers under draw ratio of 6 reached 126.9 and 452.3 °C, respectively. With the increase of the draw ratio, the tensile strength increased owing to the regular rearrangement of the molecular chains along with the axial direction, and the optimal tensile strength of P(VDF-HFP) fibers was as high as 502.6 MPa at draw raio of 6. After repeatly stretched for 50 times under constant elongation of 20%, the elastic recovery rate of P(VDF-HFP) fibers under the draw ratio of 6 was 81%, which was much higher than that of PVDF fibers, indicating that the incorporation of the HFP segments into the PVDF molecular chains was beneficial to improvement of the flexibility of the fibers.
In order to promote the development of poly(vinylidene fluoride-co-hexafluoropropylene) [P(VDF-HFP)] fibers in industry, P(VDF-HFP) fibers were fabricated via single screw melt spinning machine. The fibers were drawn by thermal stretching process, and the polyvinylidene fluoride (PVDF) fibers were prepared as a reference. The crystal structure, melting behavior and mechanical properties of the fibers were investigated by X-ray diffraction, Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), thermogravimetric analysis (TG) and fiber strength test. The results revealed that the crystal morphology of fibers had α P(VDF-HFP) and β polymorphic forms, similar to PVDF fibers contributing to the regularly stacking of VDF moiety. The addition of HFP had an effect on crystallization, resulting in lower crystallinity in P(VDF-HFP) fibers. The increase of draw ratio not only facilitated the transition of crystalline phase from α to β phase, but also improved the crystallinity of the fibers. When the tensile strength was equal, a higher transformation of the crystalline form from α to β phase was observed in P(VDF-HFP) fibers than that in PVDF fibers, due to the steric effect in HFP structural unit. The thermal stability of the fibers was also improved and their crystallization consummated with stretching. The melting temperature and thermal decomposition temperature of P(VDF-HFP) fibers under draw ratio of 6 reached 126.9 and 452.3 °C, respectively. With the increase of the draw ratio, the tensile strength increased owing to the regular rearrangement of the molecular chains along with the axial direction, and the optimal tensile strength of P(VDF-HFP) fibers was as high as 502.6 MPa at draw raio of 6. After repeatly stretched for 50 times under constant elongation of 20%, the elastic recovery rate of P(VDF-HFP) fibers under the draw ratio of 6 was 81%, which was much higher than that of PVDF fibers, indicating that the incorporation of the HFP segments into the PVDF molecular chains was beneficial to improvement of the flexibility of the fibers.
2018, 0(5): 632-638
doi: 10.11777/j.issn1000-3304.2017.17174
Abstract:
A novel diamine monomer 4-(4-trifluoromethylthiophenyl)-2,6-bis(4-aminophenyl)pyridine (FTPAP) was synthesized from 4-trifluoromethylthiobenzaldehyde and 4-nitroacetophenone by two-step reaction, and its structure was characterized via Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR) and mass spectrometry (MS). A series of novel soluble fluorinated aromatic polyamides (PA) containing pyridine ring, bulky group trifluoromethylthiophenyl and non-coplanar structure were prepared by Yamazaki phosphorylating condensation with aromatic dicarboxylic acids, such as terephthalic acid (NDA), 4-(4-carboxyphenoxy)benzoic acid (CPBA) and terephthalic acid (PTA). The structure of PA was characterized by FTIR and 1H-NMR. Gel permeation chromatography (GPC) data showed that PA has a relatively higher molecular weight and a lower dispersion coefficient, and the weight-average molecular weight and molecular weight distribution of PA were in the range of 9.30 × 104 − 1.26 × 10 5 and 1.12 − 1.33, respectively. Obviously, PA presenting excellent solubility was not only dissolved in high boiling organic solvents, such as N-methyl-2-pyrrolidone (NMP), dimethylsulfoxide (DMSO), N,N-dimethylformamide (DMF), at room temperature, but also partially dissolved in low boiling solvents, such as tetrahydrofuran (THF) and chloroform (CHCl3) under heating. Furthermore, they also showed excellent thermal properties with the glass transition temperature (Tg) in the range of 285 − 325 °C under nitrogen atmosphere, T5% and T10% weight loss temperature in the range of 396 − 435 °C and 430 − 490 °C under nitrogen atmosphere respectively, and all with a char yield above 70%. Moreover, they also showed excellent optical properties with the cutoff wavelength ranges of 369 − 384 nm, the wavelengths of 80% transmittance above 440 nm. The result of WAXD indicated that all the polymers exhibited amorphous structure. In addition, PA films also presented good mechanical properties with the tensile strength ranged from 43.2 − 95.0 MPa, Young’s modulus from 0.90 − 1.39 GPa, and the elongation at break from 3.3% − 8.8%.
A novel diamine monomer 4-(4-trifluoromethylthiophenyl)-2,6-bis(4-aminophenyl)pyridine (FTPAP) was synthesized from 4-trifluoromethylthiobenzaldehyde and 4-nitroacetophenone by two-step reaction, and its structure was characterized via Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR) and mass spectrometry (MS). A series of novel soluble fluorinated aromatic polyamides (PA) containing pyridine ring, bulky group trifluoromethylthiophenyl and non-coplanar structure were prepared by Yamazaki phosphorylating condensation with aromatic dicarboxylic acids, such as terephthalic acid (NDA), 4-(4-carboxyphenoxy)benzoic acid (CPBA) and terephthalic acid (PTA). The structure of PA was characterized by FTIR and 1H-NMR. Gel permeation chromatography (GPC) data showed that PA has a relatively higher molecular weight and a lower dispersion coefficient, and the weight-average molecular weight and molecular weight distribution of PA were in the range of 9.30 × 104 − 1.26 × 10 5 and 1.12 − 1.33, respectively. Obviously, PA presenting excellent solubility was not only dissolved in high boiling organic solvents, such as N-methyl-2-pyrrolidone (NMP), dimethylsulfoxide (DMSO), N,N-dimethylformamide (DMF), at room temperature, but also partially dissolved in low boiling solvents, such as tetrahydrofuran (THF) and chloroform (CHCl3) under heating. Furthermore, they also showed excellent thermal properties with the glass transition temperature (Tg) in the range of 285 − 325 °C under nitrogen atmosphere, T5% and T10% weight loss temperature in the range of 396 − 435 °C and 430 − 490 °C under nitrogen atmosphere respectively, and all with a char yield above 70%. Moreover, they also showed excellent optical properties with the cutoff wavelength ranges of 369 − 384 nm, the wavelengths of 80% transmittance above 440 nm. The result of WAXD indicated that all the polymers exhibited amorphous structure. In addition, PA films also presented good mechanical properties with the tensile strength ranged from 43.2 − 95.0 MPa, Young’s modulus from 0.90 − 1.39 GPa, and the elongation at break from 3.3% − 8.8%.
2018, 0(5): 639-647
doi: 10.11777/j.issn1000-3304.2017.17200
Abstract:
The surface modification of colloidal particles using intermolecular weak interactions, such as electrostatic interaction, π-π interaction, and acid-base interaction, could endow the particles with environmental stimulus responsiveness, and it is more convenient and mild compared with chemical approach. In this study, dye-hybrid polyphosphazene particles (PZS@RhB) was facilely prepared by surface modification of poly(cyclotriphosphazene-co-4,4′-sulfonyldiphenol) (PZS) particles with Rhodamine B (RhB), an acidic organic dye, by acid-base interaction. The chemical structure, morphology, surface wettability and pH-responsiveness of PZS@RhB particles were characterized by Fourier transform infrared spectroscopy, UV-Vis absorption spectroscopy, scanning electron microscopy, water contact angle test, and conductivity measurement, respectively. The emulsifying performance of PZS@RhB particles as Pickering stabilizer was further investigated, and the demulsification conditions and mechanism were also discussed. The results showed that the hydrophobicity of PZS particles was enhanced after RhB was adsorbed. Meanwhile, PZS@RhB particles exhibited pH-responsiveness due to the introduction of carboxyl groups from RhB. PZS@RhB particles could well stabilize toluene-water system (1:1, by volume) to form fine water-in-oil Pickering emulsion, when the concentration of particles in aqueous phase increased to 14 mg/mL. The obtained emulsion showed remarkable pH-responsiveness, derived from PZS@RhBparticles. The stability and type of emulsion could be changed by adjusting pH of aqueous phase. When pH increased to 10.11, the surface of PZS@RhB particles was changed from hydrophobic to hydrophilic because of the continuous ionization of carboxyl groups, and thus the transition from W/O to O/W emulsion (phase inversion) took place. In addition, it was found that the demulsification of the emulsion was easily realized by adding a low amount of triethylamine, a stronger Lewis base compared to PZS, probably because the acid-base interaction established between PZS particles and RhB was disturbed, resulting in the desorption of RhB from the surface of PZS particles. Therefore, the surface wettability of the particles was changed, and the stability of the emulsion was destroyed. Considering above features, including pH-responsiveness, phase inversion behavior, and controllable emulsification, the emulsion stabilized by PZS@RhB particles has a great potential to be applied in various fields, such as biphasic catalysis and oil-water separation.
The surface modification of colloidal particles using intermolecular weak interactions, such as electrostatic interaction, π-π interaction, and acid-base interaction, could endow the particles with environmental stimulus responsiveness, and it is more convenient and mild compared with chemical approach. In this study, dye-hybrid polyphosphazene particles (PZS@RhB) was facilely prepared by surface modification of poly(cyclotriphosphazene-co-4,4′-sulfonyldiphenol) (PZS) particles with Rhodamine B (RhB), an acidic organic dye, by acid-base interaction. The chemical structure, morphology, surface wettability and pH-responsiveness of PZS@RhB particles were characterized by Fourier transform infrared spectroscopy, UV-Vis absorption spectroscopy, scanning electron microscopy, water contact angle test, and conductivity measurement, respectively. The emulsifying performance of PZS@RhB particles as Pickering stabilizer was further investigated, and the demulsification conditions and mechanism were also discussed. The results showed that the hydrophobicity of PZS particles was enhanced after RhB was adsorbed. Meanwhile, PZS@RhB particles exhibited pH-responsiveness due to the introduction of carboxyl groups from RhB. PZS@RhB particles could well stabilize toluene-water system (1:1, by volume) to form fine water-in-oil Pickering emulsion, when the concentration of particles in aqueous phase increased to 14 mg/mL. The obtained emulsion showed remarkable pH-responsiveness, derived from PZS@RhBparticles. The stability and type of emulsion could be changed by adjusting pH of aqueous phase. When pH increased to 10.11, the surface of PZS@RhB particles was changed from hydrophobic to hydrophilic because of the continuous ionization of carboxyl groups, and thus the transition from W/O to O/W emulsion (phase inversion) took place. In addition, it was found that the demulsification of the emulsion was easily realized by adding a low amount of triethylamine, a stronger Lewis base compared to PZS, probably because the acid-base interaction established between PZS particles and RhB was disturbed, resulting in the desorption of RhB from the surface of PZS particles. Therefore, the surface wettability of the particles was changed, and the stability of the emulsion was destroyed. Considering above features, including pH-responsiveness, phase inversion behavior, and controllable emulsification, the emulsion stabilized by PZS@RhB particles has a great potential to be applied in various fields, such as biphasic catalysis and oil-water separation.
2018, 0(5): 648-655
doi: 10.11777/j.issn1000-3004.2017.17208
Abstract:
We demonstrated a novel vapor annealing method to prepare PEDOT:PSS/PVA organic conducting fiber with high electrical conductivity and high performance. PEDOT:PSS/PVA blend fiber was prepared via wet-spinning technique from homogeneous spinning formulation composed of PVA aqueous solution and PEDOT:PSS aqueous dispersions. After that, blend fibers were annealed by dimethyl sulfoxide (DMSO) vapor to improve electrical conductivity of the blend fiber. The electrical conductivity and tensile property of the blend fiber, before and after DMSO vapor annealing, were characterized to investigate the influence of vapor annealing on their structure and property. The mechanism of performance improvement was investigated in detail by analyzing their chemical structure, surface composition, chain conformation, and surface morphology. Results showed that DMSO vapor annealing induced significant structural rearrangement in blend fibers, thereby leading to improvement in the electrical conductivity. Blend fiber reached peak conductivity of 16.5 S cm–1 with the annealing time of 30 min. Vapor annealing induced phase separation between PEDOT grain and PSS segments, leading to amorphous PSS segments enriched on the surface of blend fibers, thus reducing the thickness of insulating PSS layer between adjacent PEDOT grains. Thinner PSS layer facilitated better connection between conductive PEDOT grains, which finally enhanced the conductivity of blend fibers. Vapor annealing also induced conformational transformation of PEDOT chains from benzoid structure to quinoid structure, which was favorable for charge transportation. As annealing time increased, fiber surface became smooth and surface roughness decreased. Meanwhile, tensile property of the blend fibers was also improved, with the Young’s modulus increasing from 3.0 GPa to 3.9 GPa, and the tensile strength from 110 MPa to 144 MPa. With this approach, it is possible to scale up the production to industrial scale due to the reduction of manufacturing cost. The treated PEDOT:PSS/PVA organic conducting fibers have potential wide applications such as smart electronic components in multifunctional electronic fabrics.
We demonstrated a novel vapor annealing method to prepare PEDOT:PSS/PVA organic conducting fiber with high electrical conductivity and high performance. PEDOT:PSS/PVA blend fiber was prepared via wet-spinning technique from homogeneous spinning formulation composed of PVA aqueous solution and PEDOT:PSS aqueous dispersions. After that, blend fibers were annealed by dimethyl sulfoxide (DMSO) vapor to improve electrical conductivity of the blend fiber. The electrical conductivity and tensile property of the blend fiber, before and after DMSO vapor annealing, were characterized to investigate the influence of vapor annealing on their structure and property. The mechanism of performance improvement was investigated in detail by analyzing their chemical structure, surface composition, chain conformation, and surface morphology. Results showed that DMSO vapor annealing induced significant structural rearrangement in blend fibers, thereby leading to improvement in the electrical conductivity. Blend fiber reached peak conductivity of 16.5 S cm–1 with the annealing time of 30 min. Vapor annealing induced phase separation between PEDOT grain and PSS segments, leading to amorphous PSS segments enriched on the surface of blend fibers, thus reducing the thickness of insulating PSS layer between adjacent PEDOT grains. Thinner PSS layer facilitated better connection between conductive PEDOT grains, which finally enhanced the conductivity of blend fibers. Vapor annealing also induced conformational transformation of PEDOT chains from benzoid structure to quinoid structure, which was favorable for charge transportation. As annealing time increased, fiber surface became smooth and surface roughness decreased. Meanwhile, tensile property of the blend fibers was also improved, with the Young’s modulus increasing from 3.0 GPa to 3.9 GPa, and the tensile strength from 110 MPa to 144 MPa. With this approach, it is possible to scale up the production to industrial scale due to the reduction of manufacturing cost. The treated PEDOT:PSS/PVA organic conducting fibers have potential wide applications such as smart electronic components in multifunctional electronic fabrics.
2018, 0(5): 656-664
doi: 10.11777/j.issn1000-3004.2017.170241
Abstract:
Effect of SiO2 content on cis-1,4 microstructure content of butadiene (Bd) units, intrinsic viscosity ([η]) and thermal stability of hybrid materials (PB-Si) were studied, in which SiO2 nanoparticles were covalently attached and pendants along high cis polybutadiene (PB) macromolecular chains. Isothermal crystallization characteristics and SiO2 dispersion in PB matrix of PB-Si hybrid and PB/SiO2 blend (PB/Si) with the same SiO2 contents were conducted. The microstructure of Bd units in PB-Si was characterized by Fourier transform infrared spectroscopy (FTIR) and the cis-1,4 content was determined based on the characteristic absorption in FTIR spectrum. The SiO2 content of PB-Si was measured by thermal gravimetric analysis (TGA). The intrinsic viscosity of PB-Si in toluene was tested by Ubbelohde viscometer. Effects of SiO2 content and microstructure (cis -1,4 configuration) on the isothermal crystallization kinetics, crystal morphology and spherulite growth rate of the hybrid materials at low temperatures were investigated by differential scanning calorimetry (DSC) and polarized optical microscopy (POM) equipped with in situ heating and cooling device. The results show that the intrinsic viscosity and the cis-1,4 contents of Bd units of PB-Si remained almost the same, and thermal stability could be improved with increasing SiO2 content in the materials when SiO2 content was less than 2.5%. For two series of PB-Si-Ni and PB-Si-Nd hybrids, their cis-1,4 contents were determined to be around 96.6% and 98.6% respectively. PB-Si hybrid materials exhibited a much higher crystallization rate compared to PB/Si blends by keeping the cis-1,4 contents and SiO2 content at the same. The crystallization rate increased by introducing a small amount of covalently linked SiO2 nanoparticle pendants along the macromolecular chains. The crystallization of PB-Si hybrid materials could be accelerated and the half-crystallization time (t1/2) decreased with increasing SiO2 content. PB-Si-Nd hybrid materials with highly linear chains possessed a higher crystallization rate than PB-Si-Ni with short branched chains by keeping cis-1,4 content and SiO2 at the same. The crystallization rate of PB-Si-Nd hybrid materials could be further increased with increasing both SiO2 and cis-1,4 contents. The Avrami exponents (n) for PB-Si hybrid materials with various topological structures were determined to be in the range of 2.0 − 3.0, which indicated a three-dimensional spherulite growth of PB-Si under isothermal condition at low crystallization temperature. The growth rate of spherulites increased with the increase in SiO 2 content while keeping other conditions almost the same. The crystallization rate could increase with increased cis-1,4 content, linearity of chain structure and SiO2 content.
Effect of SiO2 content on cis-1,4 microstructure content of butadiene (Bd) units, intrinsic viscosity ([η]) and thermal stability of hybrid materials (PB-Si) were studied, in which SiO2 nanoparticles were covalently attached and pendants along high cis polybutadiene (PB) macromolecular chains. Isothermal crystallization characteristics and SiO2 dispersion in PB matrix of PB-Si hybrid and PB/SiO2 blend (PB/Si) with the same SiO2 contents were conducted. The microstructure of Bd units in PB-Si was characterized by Fourier transform infrared spectroscopy (FTIR) and the cis-1,4 content was determined based on the characteristic absorption in FTIR spectrum. The SiO2 content of PB-Si was measured by thermal gravimetric analysis (TGA). The intrinsic viscosity of PB-Si in toluene was tested by Ubbelohde viscometer. Effects of SiO2 content and microstructure (cis -1,4 configuration) on the isothermal crystallization kinetics, crystal morphology and spherulite growth rate of the hybrid materials at low temperatures were investigated by differential scanning calorimetry (DSC) and polarized optical microscopy (POM) equipped with in situ heating and cooling device. The results show that the intrinsic viscosity and the cis-1,4 contents of Bd units of PB-Si remained almost the same, and thermal stability could be improved with increasing SiO2 content in the materials when SiO2 content was less than 2.5%. For two series of PB-Si-Ni and PB-Si-Nd hybrids, their cis-1,4 contents were determined to be around 96.6% and 98.6% respectively. PB-Si hybrid materials exhibited a much higher crystallization rate compared to PB/Si blends by keeping the cis-1,4 contents and SiO2 content at the same. The crystallization rate increased by introducing a small amount of covalently linked SiO2 nanoparticle pendants along the macromolecular chains. The crystallization of PB-Si hybrid materials could be accelerated and the half-crystallization time (t1/2) decreased with increasing SiO2 content. PB-Si-Nd hybrid materials with highly linear chains possessed a higher crystallization rate than PB-Si-Ni with short branched chains by keeping cis-1,4 content and SiO2 at the same. The crystallization rate of PB-Si-Nd hybrid materials could be further increased with increasing both SiO2 and cis-1,4 contents. The Avrami exponents (n) for PB-Si hybrid materials with various topological structures were determined to be in the range of 2.0 − 3.0, which indicated a three-dimensional spherulite growth of PB-Si under isothermal condition at low crystallization temperature. The growth rate of spherulites increased with the increase in SiO 2 content while keeping other conditions almost the same. The crystallization rate could increase with increased cis-1,4 content, linearity of chain structure and SiO2 content.
