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1995 Volume 13 Issue 4
1995, 13(4): 289-314
Abstract:
1995, 13(4): 315-321
Abstract:
An oral drug delivery system using proteinoid microspheres is discussed with respect to itsunique dependence on pH. It has been found that certain drugs such as insulin and heparin canbe encapsulated in proteinoid spheres at stomach pH's (1--3). These spheres also dissemble atintestinal pH's (6--7) releasing the drug for absorption. Using this technique low molecularweight heparin and human growth hormone have been orally delivered successfully to severalanimal species. Future work has been proposed to study the interaction and binding of the specific drugs with synthesized oligopeptides.
An oral drug delivery system using proteinoid microspheres is discussed with respect to itsunique dependence on pH. It has been found that certain drugs such as insulin and heparin canbe encapsulated in proteinoid spheres at stomach pH's (1--3). These spheres also dissemble atintestinal pH's (6--7) releasing the drug for absorption. Using this technique low molecularweight heparin and human growth hormone have been orally delivered successfully to severalanimal species. Future work has been proposed to study the interaction and binding of the specific drugs with synthesized oligopeptides.
1995, 13(4): 322-330
Abstract:
Photoinduced grafting of acrylic and allyl monomers on polyethylene surface wasgenerally studied by using benzophenone (BP) as a photoinitiator. The grafting process wascarried out either in vapor-phase or in solution of the monomers. In the vapor-phase reactionwith a filter used to cut off the short wavelength UV light, allyl amine is the most reactive ofthe four monomers used and acrylic amide is comparatively more reactive than acrylic acid andallyl alcohol. Acetone, as a solvent and carrier for initiator and monomers,however,shows its reactivity to participate the reaction.The solution grafting with a filter is much faster than the corresponding vapor-phase reaction,and a fullt covered surface by the grafted polymer can be achieved in this way.
Photoinduced grafting of acrylic and allyl monomers on polyethylene surface wasgenerally studied by using benzophenone (BP) as a photoinitiator. The grafting process wascarried out either in vapor-phase or in solution of the monomers. In the vapor-phase reactionwith a filter used to cut off the short wavelength UV light, allyl amine is the most reactive ofthe four monomers used and acrylic amide is comparatively more reactive than acrylic acid andallyl alcohol. Acetone, as a solvent and carrier for initiator and monomers,however,shows its reactivity to participate the reaction.The solution grafting with a filter is much faster than the corresponding vapor-phase reaction,and a fullt covered surface by the grafted polymer can be achieved in this way.
1995, 13(4): 331-337
Abstract:
A silica-supported poly-γ- aminopropylsiloxane-rhodium-cobalt bimetallic complex(abbreviated as SiO2-NH2-Rh-Co)has been prepared and used as catalyst for hydroformylationof methyl methacrylate. The results showed that the catalyst could catalyze the reaction in95.6% conversion with 92.8% selectivity for the normal aldehyde, methyl β-formylisobu-tyrate. Such catalyst also showed high stability during the reaction and could be used repeat-edly.
A silica-supported poly-γ- aminopropylsiloxane-rhodium-cobalt bimetallic complex(abbreviated as SiO2-NH2-Rh-Co)has been prepared and used as catalyst for hydroformylationof methyl methacrylate. The results showed that the catalyst could catalyze the reaction in95.6% conversion with 92.8% selectivity for the normal aldehyde, methyl β-formylisobu-tyrate. Such catalyst also showed high stability during the reaction and could be used repeat-edly.
1995, 13(4): 338-346
Abstract:
A series of high performance lubricants of water-soluble polymers with telechelic or starstructures has been studied. Their average molecular weights M are 1800--6000. The chemi-cal structures of the lubricants are characterized by their hydrophilic groups (--CH2CH2O--),--COOH, --OH, --CONH2 and antiwear active elements (S, P,Zn and Mo). The results ofassessing for the anti-wear property indicate that this kind of water-soluble polymeric lubri-cants possesses excellent watersolubility, lubricity and anti-wear property.A preliminary study on the anti-wear mechanism of the polymers is performed by means of electron probe and scanning eletron microscopy (SEM).
A series of high performance lubricants of water-soluble polymers with telechelic or starstructures has been studied. Their average molecular weights M are 1800--6000. The chemi-cal structures of the lubricants are characterized by their hydrophilic groups (--CH2CH2O--),--COOH, --OH, --CONH2 and antiwear active elements (S, P,Zn and Mo). The results ofassessing for the anti-wear property indicate that this kind of water-soluble polymeric lubri-cants possesses excellent watersolubility, lubricity and anti-wear property.A preliminary study on the anti-wear mechanism of the polymers is performed by means of electron probe and scanning eletron microscopy (SEM).
1995, 13(4): 347-352
Abstract:
This paper presents our work on the rheological properties of the solution of polyaniline(PAn) in N-methyl-2-pyrrolidone (NMP). The result s indicate that the solution's non-Newtonian property becomes more prominent with the increase in solution-oncentration,exhibiting the behavior of pseudo-plastic fluid. Besides, there is a critical concentration C.(around 0.06 g/ml), beyond which the viscosity of the PAn/NMP solution takes a suddenincrease. With temperature rising, both the viscosity and the thixotropy of the solution decrease,implying that there exist physical cross-linking interactions between the molecular chains in the solution.
This paper presents our work on the rheological properties of the solution of polyaniline(PAn) in N-methyl-2-pyrrolidone (NMP). The result s indicate that the solution's non-Newtonian property becomes more prominent with the increase in solution-oncentration,exhibiting the behavior of pseudo-plastic fluid. Besides, there is a critical concentration C.(around 0.06 g/ml), beyond which the viscosity of the PAn/NMP solution takes a suddenincrease. With temperature rising, both the viscosity and the thixotropy of the solution decrease,implying that there exist physical cross-linking interactions between the molecular chains in the solution.
1995, 13(4): 353-360
Abstract:
Flexible oxyethylene-ether was introduced into the aromatic copolyesters and copoly(es-ter-amide)s to reduce the melting point of resulting polymers. The melting point was greatlyreduced to 200℃ or even lower in some cases, and the molecular weight was satisfactorilyhigh as reflected by inherent viscosity. The polymers exhibited high thermal stability and goodmechanical properties as determined by TGA and mechanical tests. The copolyester showedbetter crystallinity and liquid crystallinity than corresponding copoly(ester-amide)s with similar monomer composition as reflected by POM observation and WAXD study.The melting points for both copolyesters and copoly(seter-amide)s showed great dependence on the pacetoxybenzoic acid(PAB) content in monomer composition and reached the lowest value when PAB was 29 mol%.
Flexible oxyethylene-ether was introduced into the aromatic copolyesters and copoly(es-ter-amide)s to reduce the melting point of resulting polymers. The melting point was greatlyreduced to 200℃ or even lower in some cases, and the molecular weight was satisfactorilyhigh as reflected by inherent viscosity. The polymers exhibited high thermal stability and goodmechanical properties as determined by TGA and mechanical tests. The copolyester showedbetter crystallinity and liquid crystallinity than corresponding copoly(ester-amide)s with similar monomer composition as reflected by POM observation and WAXD study.The melting points for both copolyesters and copoly(seter-amide)s showed great dependence on the pacetoxybenzoic acid(PAB) content in monomer composition and reached the lowest value when PAB was 29 mol%.
1995, 13(4): 361-365
Abstract:
Semi-rigid liquid crystal polymer is a class of liquid crystal polymers different from long rigidrod liquid crystal polymer to which the well-known Onsager and Flory theories are applied. Inthis paper, three statistical models for the semi-rigid nematic polymer were addressed. They arethe elastically jointed rod model, worm-like chain model, and non--homogeneous chain model.The nematic-isotropic transition temperature was examined. The pseudo-second transition tem-perature is expressed analytically. Comparisons with the experiments were made and the agreements were found.
Semi-rigid liquid crystal polymer is a class of liquid crystal polymers different from long rigidrod liquid crystal polymer to which the well-known Onsager and Flory theories are applied. Inthis paper, three statistical models for the semi-rigid nematic polymer were addressed. They arethe elastically jointed rod model, worm-like chain model, and non--homogeneous chain model.The nematic-isotropic transition temperature was examined. The pseudo-second transition tem-perature is expressed analytically. Comparisons with the experiments were made and the agreements were found.
1995, 13(4): 366-374
Abstract:
The chemical structure of copolymer formed in the transesterification of PPSQ/PET blendsduring melt-processing is deduced from the 1H-NMR spectra. The transesterification extent ofthis blend is interpreted by the changes of crystalline melting peak in DSC thermograms of the in-soluble products containing unreacted PET and some block PPSQ segments. Effects of composi-tion of blend ladderlike regularity of PPSQ on the reaction extent have also been discussed.Inclusion of some block PPSQ segments in PET has no influence on the crystalline morphology of PET.
The chemical structure of copolymer formed in the transesterification of PPSQ/PET blendsduring melt-processing is deduced from the 1H-NMR spectra. The transesterification extent ofthis blend is interpreted by the changes of crystalline melting peak in DSC thermograms of the in-soluble products containing unreacted PET and some block PPSQ segments. Effects of composi-tion of blend ladderlike regularity of PPSQ on the reaction extent have also been discussed.Inclusion of some block PPSQ segments in PET has no influence on the crystalline morphology of PET.
1995, 13(4): 375-380
Abstract:
The miscibility of poly (ethylene terephthalate (ET) -- caprolactone (CL) (TCL)/poly(ethylene terephthalate) (PET) blends were examined by Differential Scanning Calorimeter(DSC). In these blends, a miscibility limit specified by ET content in the TCL was found tobe about 70 (wt%). In the blends of TCL/TCL with different ET contents, a miscibilitywindow defined by ET content was also found to range from 82 to 58 (wt%). Based on theexperimental miscibility limits and the mean field binary interaction model, the interaction parameter between monomeric units of ET and CL was obtained.
The miscibility of poly (ethylene terephthalate (ET) -- caprolactone (CL) (TCL)/poly(ethylene terephthalate) (PET) blends were examined by Differential Scanning Calorimeter(DSC). In these blends, a miscibility limit specified by ET content in the TCL was found tobe about 70 (wt%). In the blends of TCL/TCL with different ET contents, a miscibilitywindow defined by ET content was also found to range from 82 to 58 (wt%). Based on theexperimental miscibility limits and the mean field binary interaction model, the interaction parameter between monomeric units of ET and CL was obtained.
1995, 13(4): 381-384
Abstract:
The cationic polymerization of 1, 3-pentadiene was initiated by the organic azide/Et2 AlClinitiating system in CH2Cl2 and n-hexane. The polymerizations were also carried out in parallelwith organic chloride/Et2AlCl and Et2 AlCl alone for comparison. The Et2 AlCl- induced polymer-ization gives a low yield while the polymerization initiated by organic chloride/Et2 AlCl producesmainly insoluble product. In contrast, the polymerization with azide/Et,AlCl has a high conver-sion and the resulting polymer having a high molecular weight is totally soluble.The SEC spectra of the polymers have clearly shown the differences between these initiating systems.s
The cationic polymerization of 1, 3-pentadiene was initiated by the organic azide/Et2 AlClinitiating system in CH2Cl2 and n-hexane. The polymerizations were also carried out in parallelwith organic chloride/Et2AlCl and Et2 AlCl alone for comparison. The Et2 AlCl- induced polymer-ization gives a low yield while the polymerization initiated by organic chloride/Et2 AlCl producesmainly insoluble product. In contrast, the polymerization with azide/Et,AlCl has a high conver-sion and the resulting polymer having a high molecular weight is totally soluble.The SEC spectra of the polymers have clearly shown the differences between these initiating systems.s
