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2000 Volume 18 Issue 1
2000, 18(1): 1-7
Abstract:
We describe the sol-gel synthesis of a new family of organic-inorganic hybrid materials, in which various vinylpolymers are covalently bonded to and uniformly distributed in inorganic oxide matrices. The materials can be tailored tohave both good toughness and hardness while maintaining excellent optical transparency. Doping the sol-gel metal oxideswith optically active compounds such as D-glucose results in new optical rotatory composite materials. Removal of thedopant compounds from the composites affords...
We describe the sol-gel synthesis of a new family of organic-inorganic hybrid materials, in which various vinylpolymers are covalently bonded to and uniformly distributed in inorganic oxide matrices. The materials can be tailored tohave both good toughness and hardness while maintaining excellent optical transparency. Doping the sol-gel metal oxideswith optically active compounds such as D-glucose results in new optical rotatory composite materials. Removal of thedopant compounds from the composites affords...
2000, 18(1): 9-13
Abstract:
A new class of poly(ester-imide-ether) multiblock copolymers was synthesized by transes-terification and meltcopolymerization of dimethyl terephthalate (DMT) and N-(4-carbomethoxyphenyl)-4-(carbomethoxy)-phthalimide withethylene glycol (EG) and polytetramethylene glycol (PTMG). The structure of the above copolymers was characterized by1H-NMR and IR spectroscopy. Some properties of the coplymers were also examined. It was found that their mechanicalproperties and heat stability, compared with poly(ether-ester)copolymers,were obviously improved.
A new class of poly(ester-imide-ether) multiblock copolymers was synthesized by transes-terification and meltcopolymerization of dimethyl terephthalate (DMT) and N-(4-carbomethoxyphenyl)-4-(carbomethoxy)-phthalimide withethylene glycol (EG) and polytetramethylene glycol (PTMG). The structure of the above copolymers was characterized by1H-NMR and IR spectroscopy. Some properties of the coplymers were also examined. It was found that their mechanicalproperties and heat stability, compared with poly(ether-ester)copolymers,were obviously improved.
2000, 18(1): 15-17
Abstract:
The critical concentration of lyotropic liquid crystalline phase transition for chitin derivatives was determinedusing a polarization microscope. The influence of molecular weight on critical concentration of liquid crystalline solution forchitin, chitosan, cyanoethyl chitosan and propionyl chitin successively increases as the chain rigidity decreases. Therefore itcan be used as an indicator of the chain rigidity.
The critical concentration of lyotropic liquid crystalline phase transition for chitin derivatives was determinedusing a polarization microscope. The influence of molecular weight on critical concentration of liquid crystalline solution forchitin, chitosan, cyanoethyl chitosan and propionyl chitin successively increases as the chain rigidity decreases. Therefore itcan be used as an indicator of the chain rigidity.
2000, 18(1): 19-23
Abstract:
A novel kind of copolymer with ABA-type block structure was synthesized by anionic ring-openingpolymerization of β-butyrolactone (β-BL) in the presence of a PEG-based dicarboxylates as macroinitiators which wereprepared by the esterification of aliphatic cyclic anhydride and poly(ethylene glycol) (PEG) oligomers (Mn=2000, 4000 and6000) and conversion of potassium dicarboxylates. The resultant copolymers as well as the intermediates were characterizedby IR,1H-NMR and GPC.
A novel kind of copolymer with ABA-type block structure was synthesized by anionic ring-openingpolymerization of β-butyrolactone (β-BL) in the presence of a PEG-based dicarboxylates as macroinitiators which wereprepared by the esterification of aliphatic cyclic anhydride and poly(ethylene glycol) (PEG) oligomers (Mn=2000, 4000 and6000) and conversion of potassium dicarboxylates. The resultant copolymers as well as the intermediates were characterizedby IR,1H-NMR and GPC.
2000, 18(1): 25-31
Abstract:
A kind of macroporous bead carrier of copolymer containing monomer units of N-aminoethyl acrylamide and vinylalcohol was synthesized, i.e. the MR-AA carrier. Papain was immobilized on the carrier using glutaraldehyde as the couplingagent. The enzymatic activity of the immobilized papain was compared with free papain using casein as a substrate, and theeffects of glutaraldehyde concentration, pH, temperature, time and papain amount added on the activity recovery were alsoinvestigated. The results show that the MR-AA carrier contains reactive primary amine groups,hydrophilic amido links and hydroxyl groups,as well as macroporous structures based on its matrix (MR-AV matrix),furthermore,the activity recovery of papain in the immobilization could reach 48%～58%.In comparison with free papain,the resulting immobilized papain exhibits a remarkable thermostability and better reusability.
A kind of macroporous bead carrier of copolymer containing monomer units of N-aminoethyl acrylamide and vinylalcohol was synthesized, i.e. the MR-AA carrier. Papain was immobilized on the carrier using glutaraldehyde as the couplingagent. The enzymatic activity of the immobilized papain was compared with free papain using casein as a substrate, and theeffects of glutaraldehyde concentration, pH, temperature, time and papain amount added on the activity recovery were alsoinvestigated. The results show that the MR-AA carrier contains reactive primary amine groups,hydrophilic amido links and hydroxyl groups,as well as macroporous structures based on its matrix (MR-AV matrix),furthermore,the activity recovery of papain in the immobilization could reach 48%～58%.In comparison with free papain,the resulting immobilized papain exhibits a remarkable thermostability and better reusability.
2000, 18(1): 33-38
Abstract:
The phase inversion emulsification technique (PIET) is an effective physical method for preparing waterbornedispersions of polymer resins. Some results concerning the preparation of bisphenol A epoxy resin waterborne dispersions byPIET in our laboratory were summarized. Electrical properties, rheological behavior and morphological evolution duringphase inversion progress were systematically characterized. The effects of the emulsifier concentration and emulsification temperature on phase inversion progress and the structural features of the waterborne particles were studied as well.The deformation and break up of water drops in a shear field were analyzed in terms of micro-rheology,while the interaction and coalescence dynamics of water drops were discussed in terms of DLVO theory and Smoluchowski effective collision theory,respectively.Based on the experimental results and theoretical analysis,a physical model of phase inversion progress was suggested,by which the effects of the parameters on phase inversion progress and the structural features of the waterborne particles were interpreted and predicted.
The phase inversion emulsification technique (PIET) is an effective physical method for preparing waterbornedispersions of polymer resins. Some results concerning the preparation of bisphenol A epoxy resin waterborne dispersions byPIET in our laboratory were summarized. Electrical properties, rheological behavior and morphological evolution duringphase inversion progress were systematically characterized. The effects of the emulsifier concentration and emulsification temperature on phase inversion progress and the structural features of the waterborne particles were studied as well.The deformation and break up of water drops in a shear field were analyzed in terms of micro-rheology,while the interaction and coalescence dynamics of water drops were discussed in terms of DLVO theory and Smoluchowski effective collision theory,respectively.Based on the experimental results and theoretical analysis,a physical model of phase inversion progress was suggested,by which the effects of the parameters on phase inversion progress and the structural features of the waterborne particles were interpreted and predicted.
2000, 18(1): 39-43
Abstract:
Alpha-trichloroacetoxy terminated polystyrene oligomer (PS-CH2CH2OCOCCl3) and poly-(styrene-b-butadiene)oligomer [P(S-b-B)-CH2CH2OCOCCl3)] were synthesized by living anionic polymeri-zation using n-butyllithium as initiator.Then the PS-CH2CH2OCOCCl3 (PS-Cl3) or P(S-b-B)-CH2CH2O-COCCl3 (PSB-Cl3) was used as the macroinitiator in thepolymerization of (meth)acrylates in the presence of CuX/bpy. AB diblock and ABC triblock copolymers were prepared bythe integrated living anionic polymerization (LAP)-atom transfer radical polymerization (ATRP).The structures of the PSBCl3 and the P(S-b-MMA) were identified by FTIR and 1H-NMR spectrum,respectively.A new way to design block copolymers (the combination of LAP and ATRP)was developed.
Alpha-trichloroacetoxy terminated polystyrene oligomer (PS-CH2CH2OCOCCl3) and poly-(styrene-b-butadiene)oligomer [P(S-b-B)-CH2CH2OCOCCl3)] were synthesized by living anionic polymeri-zation using n-butyllithium as initiator.Then the PS-CH2CH2OCOCCl3 (PS-Cl3) or P(S-b-B)-CH2CH2O-COCCl3 (PSB-Cl3) was used as the macroinitiator in thepolymerization of (meth)acrylates in the presence of CuX/bpy. AB diblock and ABC triblock copolymers were prepared bythe integrated living anionic polymerization (LAP)-atom transfer radical polymerization (ATRP).The structures of the PSBCl3 and the P(S-b-MMA) were identified by FTIR and 1H-NMR spectrum,respectively.A new way to design block copolymers (the combination of LAP and ATRP)was developed.
2000, 18(1): 45-49
Abstract:
Solution crystallization of metallocene short chain branched polyethylene (SCBPE) was carried out and very nicesingle crystals were obtained. Compared with single crystals grown from linear polyethylene, SCBPE single crystals are dirtydue to intermolecular heterogeneity The crystal morphology changes with crystallization temperatures. Lozenge, truncatedlozenge, hexagonal, rounded and elongated crystal morphologies have been found at much lower crystallization temperaturethan in linear polyethylene. The electron diffraction shows there is a possibility that the single crystals may have hexagonal packing in a crystallization temperature range.The lateral habits of single crystal are discussed based on roughening theories.
Solution crystallization of metallocene short chain branched polyethylene (SCBPE) was carried out and very nicesingle crystals were obtained. Compared with single crystals grown from linear polyethylene, SCBPE single crystals are dirtydue to intermolecular heterogeneity The crystal morphology changes with crystallization temperatures. Lozenge, truncatedlozenge, hexagonal, rounded and elongated crystal morphologies have been found at much lower crystallization temperaturethan in linear polyethylene. The electron diffraction shows there is a possibility that the single crystals may have hexagonal packing in a crystallization temperature range.The lateral habits of single crystal are discussed based on roughening theories.
2000, 18(1): 51-55
Abstract:
Trimethylsilylated silica was synthesized through hydrolytic condensation of tetraethoxysilane followed bytrimethylsilylation. Rheological properties of the silicone resin with trimethylsilylated silica as modifier were studied. Itturned out that the particle size of silica was important to the rheological behavior of the modified resin. Trimethylsilylatedsilica of medium particle size shows the strongest tendency of forming physical network in the resin.
Trimethylsilylated silica was synthesized through hydrolytic condensation of tetraethoxysilane followed bytrimethylsilylation. Rheological properties of the silicone resin with trimethylsilylated silica as modifier were studied. Itturned out that the particle size of silica was important to the rheological behavior of the modified resin. Trimethylsilylatedsilica of medium particle size shows the strongest tendency of forming physical network in the resin.
2000, 18(1): 57-67
Abstract:
The concentration dependence of the reduced viscosity of dilute polymer solution is interpreted in the light of anew concept of the self-association of polymer chains in dilute solution. The apparent self-association constant is defined asthe molar association constant divided by the molar mass of individual polymer chain and is numerically interconvertiblewith the Huggins coefficient. The molar association constant is directly proportional to the effective hydrodynamic volume of the polymer chain in solution and is irrespective of the chain architecture.The effective hydrodynamic volume accounts for the non-spherical conformation of a short polymer chain in solution and is a product of a shape factor and hydrodynamic volume.The observed enhancement of Huggins coefficient for short chain and branched polymer is satisfactorily interpreted by the concept of self-association.The concept of self-association allows us to predict the existence of a boundary concentration Cs (dynamic contact concentration )with divides the dilute polymer solution into two regions.
The concentration dependence of the reduced viscosity of dilute polymer solution is interpreted in the light of anew concept of the self-association of polymer chains in dilute solution. The apparent self-association constant is defined asthe molar association constant divided by the molar mass of individual polymer chain and is numerically interconvertiblewith the Huggins coefficient. The molar association constant is directly proportional to the effective hydrodynamic volume of the polymer chain in solution and is irrespective of the chain architecture.The effective hydrodynamic volume accounts for the non-spherical conformation of a short polymer chain in solution and is a product of a shape factor and hydrodynamic volume.The observed enhancement of Huggins coefficient for short chain and branched polymer is satisfactorily interpreted by the concept of self-association.The concept of self-association allows us to predict the existence of a boundary concentration Cs (dynamic contact concentration )with divides the dilute polymer solution into two regions.
2000, 18(1): 69-75
Abstract:
Isothermal recovery in the macroscopic length of homogeneously deformed specimens of amorphous poly(ethyleneterephthalate) (PET) film sample uniaxially drawn at 69℃ to the draw ratios λ0=1.26～2.20 were studied at temperaturesaround the glass transition temperature (Tg = 73℃). Experimental results indicate that the length recovery took place in twodistinct steps: a fast first step (fast relaxation) followed by a slow second step (slow relaxation). The relaxation processeswere accompanied by the reversion of trans-conformers (1340cm-1 to gauche,and the dichroic function of the 1340 cm-1band characterizing the segmental orientation along the chain direction decreased to a very low value at the end of the fast relaxation.This fact led us to assign the fast relaxation as the segmental orientation while the slow relaxation as relaxation of the global chain orientation.It was found that the slow relaxation follows a single exponential function,with relaxation times strongly dependent on the temperature resembling the glass transition process.The fast relaxation does not follow a single exponenitial decay,presumably a distribution of relaxation times is involved.
Isothermal recovery in the macroscopic length of homogeneously deformed specimens of amorphous poly(ethyleneterephthalate) (PET) film sample uniaxially drawn at 69℃ to the draw ratios λ0=1.26～2.20 were studied at temperaturesaround the glass transition temperature (Tg = 73℃). Experimental results indicate that the length recovery took place in twodistinct steps: a fast first step (fast relaxation) followed by a slow second step (slow relaxation). The relaxation processeswere accompanied by the reversion of trans-conformers (1340cm-1 to gauche,and the dichroic function of the 1340 cm-1band characterizing the segmental orientation along the chain direction decreased to a very low value at the end of the fast relaxation.This fact led us to assign the fast relaxation as the segmental orientation while the slow relaxation as relaxation of the global chain orientation.It was found that the slow relaxation follows a single exponential function,with relaxation times strongly dependent on the temperature resembling the glass transition process.The fast relaxation does not follow a single exponenitial decay,presumably a distribution of relaxation times is involved.
2000, 18(1): 77-80
Abstract:
Ring-opening polymerization of trimethylene carbonate (TMC) with a rare earth calixarene compound as catalysthas been studied for the first time. The effect of TMC/Nd (molar ratio) and polymerization conditions were investigated indetail. It was found that calix[8]arene-neodymium is a highly effective catalyst for the bulk polymerization of TMC and giveshigh molecular weight (Mv = 60,000) polymer. The optimum conditions of TMC polymerization were found to be as follows:TMC/Nd(molar ratio)=2,000,80℃,16h.The polymers were characterized by NMR,GPC and DSC.Studying the mechanism by NMR showed that the polymerization of TMC catalyzed by calix[8]arene-neodymium proceeds via a cationic mechanism.
Ring-opening polymerization of trimethylene carbonate (TMC) with a rare earth calixarene compound as catalysthas been studied for the first time. The effect of TMC/Nd (molar ratio) and polymerization conditions were investigated indetail. It was found that calix[8]arene-neodymium is a highly effective catalyst for the bulk polymerization of TMC and giveshigh molecular weight (Mv = 60,000) polymer. The optimum conditions of TMC polymerization were found to be as follows:TMC/Nd(molar ratio)=2,000,80℃,16h.The polymers were characterized by NMR,GPC and DSC.Studying the mechanism by NMR showed that the polymerization of TMC catalyzed by calix[8]arene-neodymium proceeds via a cationic mechanism.
2000, 18(1): 81-86
Abstract:
By means of polarizing optical microscopy (POM), deformation behavior of four kinds of fibers, i.e. ultra highmolecular weight polyethylene (UHMW-PE) fiber, polyvinyl alcohol (PVA) fiber, polyethylene terephthalate (PET) fiber,and wholly aromatic (p-hydroxybenzoic acid/2-hydroxy-6-naphthoic acid) copolyester [P(HBA/HNA)]/PET (ACPET blend)fiber, in axial compression, axial impacting, and bending was observed. In compression, kink bands formed at an angle of55～60° to the fiber axis in 10-times-drawn UHMW-PE fiber,75～80° in 40-times-drawn sample,80°in PVA fiber,and 90°in the ACPET blend fiber.In impacting and bending,band angles of UHMW-PE,PVA and PET fibers are nearly the same as those formed in compression,indicating that slip systems do not change.For any of the four kinds of fiber,band spacing exhibits great differences in compression,in impacting,and in bending,which may be attributed to the differences in the degrees of strain or stress concentration.
By means of polarizing optical microscopy (POM), deformation behavior of four kinds of fibers, i.e. ultra highmolecular weight polyethylene (UHMW-PE) fiber, polyvinyl alcohol (PVA) fiber, polyethylene terephthalate (PET) fiber,and wholly aromatic (p-hydroxybenzoic acid/2-hydroxy-6-naphthoic acid) copolyester [P(HBA/HNA)]/PET (ACPET blend)fiber, in axial compression, axial impacting, and bending was observed. In compression, kink bands formed at an angle of55～60° to the fiber axis in 10-times-drawn UHMW-PE fiber,75～80° in 40-times-drawn sample,80°in PVA fiber,and 90°in the ACPET blend fiber.In impacting and bending,band angles of UHMW-PE,PVA and PET fibers are nearly the same as those formed in compression,indicating that slip systems do not change.For any of the four kinds of fiber,band spacing exhibits great differences in compression,in impacting,and in bending,which may be attributed to the differences in the degrees of strain or stress concentration.
