Login In
1998 Volume 16 Issue 1
1998, 16(1): 1-8
Abstract:
The electrical and mechanical properties of polyaniline (PANI) films syn-thesized by the presence of the selected neutral salts in the polymerization were measuredas a function of the properties and the concentration of the selected neutral salts, andthe protonation state. It was found that both the electrical and mechanical properties ofPANI films were enhanced by adding neutral salts in the polymerization. The adding ofthe neutral salts in the polymerization resulted in extended conformation of polymer chain and increasing of molecular weight of PANI,which may be the reasons why the electrical and mechanical properties of PANI films were improved by the presence of neutral salts in the polymerization.
The electrical and mechanical properties of polyaniline (PANI) films syn-thesized by the presence of the selected neutral salts in the polymerization were measuredas a function of the properties and the concentration of the selected neutral salts, andthe protonation state. It was found that both the electrical and mechanical properties ofPANI films were enhanced by adding neutral salts in the polymerization. The adding ofthe neutral salts in the polymerization resulted in extended conformation of polymer chain and increasing of molecular weight of PANI,which may be the reasons why the electrical and mechanical properties of PANI films were improved by the presence of neutral salts in the polymerization.
1998, 16(1): 9-17
Abstract:
Side chain liquid crystalline polysiloxanes containing benzyl ether linkingunits were synthesized by the hydrosilylation of poly (methylhydrosiloxane) with a series of4-(4-alkoxybenzyloxy)-4'-allyloxybiphenyl monomers [4-(4-methoxybenzyloxy )-4'-allyloxy-biphenyl(M1), 4-(4-ethoxybenzyloxy)-4'-allyloxybiphenyl (M2), 4-(4-propoxybenzyloxy)-4'-allyloxybiphenyl (M3), 4-(4-butoxybenzyloxy)-4'-allylox(M4), 4-(4-pentoxy-benzyloxy)-4'-allyloxybiphenyl (M5), 4-benzyloxy-4'-allyloxybiphenyl (M6)]. The phase behavior of monomeric and polymeric liquid crystals was characterized by differential scanning calorimetry and optical polarization microscopy where the groups are ranged from methoxy to pentoxy.Both the monomeric and polymeric liquid crystals exhibit liquid crystal behaviors.
Side chain liquid crystalline polysiloxanes containing benzyl ether linkingunits were synthesized by the hydrosilylation of poly (methylhydrosiloxane) with a series of4-(4-alkoxybenzyloxy)-4'-allyloxybiphenyl monomers [4-(4-methoxybenzyloxy )-4'-allyloxy-biphenyl(M1), 4-(4-ethoxybenzyloxy)-4'-allyloxybiphenyl (M2), 4-(4-propoxybenzyloxy)-4'-allyloxybiphenyl (M3), 4-(4-butoxybenzyloxy)-4'-allylox(M4), 4-(4-pentoxy-benzyloxy)-4'-allyloxybiphenyl (M5), 4-benzyloxy-4'-allyloxybiphenyl (M6)]. The phase behavior of monomeric and polymeric liquid crystals was characterized by differential scanning calorimetry and optical polarization microscopy where the groups are ranged from methoxy to pentoxy.Both the monomeric and polymeric liquid crystals exhibit liquid crystal behaviors.
1998, 16(1): 18-24
Abstract:
Two kinds of side chain liquid crystalline polysiloxanes containing crownether and benzyl ether were synthesized and characterized by optical polarization mi-croscopy. Both the monomeric liquid crystals and polymeric liquid crystals show smecticphases.
Two kinds of side chain liquid crystalline polysiloxanes containing crownether and benzyl ether were synthesized and characterized by optical polarization mi-croscopy. Both the monomeric liquid crystals and polymeric liquid crystals show smecticphases.
1998, 16(1): 25-31
Abstract:
The copolymerization of 2-hydroxyethyl acrylate (HEA, M1) and methylmethacrylate (MMA, M2) in cyclohexanone was studied. The multiple experiments ofsolution copolymerization with low conversion were carried out at two sensitive compositionfeed points at 60, 80, 100, 120 and 140℃, respectively. The composition of the copolymerswas analyzed by 1H-NMR. The reactivity ratios which were estimated by the Error-in-Variable Method (EVM) of Mayo-Lewis equation were found to be r1 = 0.328, r2 = 1.781for 60℃; 0.375,1.709 for 80℃;0.406,1.654 for 100℃;0.439,1.540 for 120℃ and 0.455,1.400 for 140℃,and the 95% joint confidence intervals of the reactivity ratios were also determined.According to r1 and r2,Arrhenius relations and the activity energy difference between the homo- and cross-propagation were calculated.
The copolymerization of 2-hydroxyethyl acrylate (HEA, M1) and methylmethacrylate (MMA, M2) in cyclohexanone was studied. The multiple experiments ofsolution copolymerization with low conversion were carried out at two sensitive compositionfeed points at 60, 80, 100, 120 and 140℃, respectively. The composition of the copolymerswas analyzed by 1H-NMR. The reactivity ratios which were estimated by the Error-in-Variable Method (EVM) of Mayo-Lewis equation were found to be r1 = 0.328, r2 = 1.781for 60℃; 0.375,1.709 for 80℃;0.406,1.654 for 100℃;0.439,1.540 for 120℃ and 0.455,1.400 for 140℃,and the 95% joint confidence intervals of the reactivity ratios were also determined.According to r1 and r2,Arrhenius relations and the activity energy difference between the homo- and cross-propagation were calculated.
1998, 16(1): 32-37
Abstract:
Copolymerization of ethylene/1-octene was carried out in toluene withvarious concentrations of comonomer in the feed using Et(Ind)2ZrCl2/MAO (methyl alu-minoxane) as catalyst. It was found that with the increase of 1-octene concentration in thefeed the content of 1-octene in the copolymer increases, while the density, melting point,crystallinity and intrinsic viscosity of copolymer decrease. A copolymer with very lowdensity, containing 11.5 mol% of 1-octene (VLLDPE) can be produced with this catalyst system.The effect of temperature and zirconium aluminum mole ratio of the catalyst on the copolymerization was also investigated.The results of 13C NMR determination of the copolymer showed that the 1-octene units in the copolymer are principally isolated.
Copolymerization of ethylene/1-octene was carried out in toluene withvarious concentrations of comonomer in the feed using Et(Ind)2ZrCl2/MAO (methyl alu-minoxane) as catalyst. It was found that with the increase of 1-octene concentration in thefeed the content of 1-octene in the copolymer increases, while the density, melting point,crystallinity and intrinsic viscosity of copolymer decrease. A copolymer with very lowdensity, containing 11.5 mol% of 1-octene (VLLDPE) can be produced with this catalyst system.The effect of temperature and zirconium aluminum mole ratio of the catalyst on the copolymerization was also investigated.The results of 13C NMR determination of the copolymer showed that the 1-octene units in the copolymer are principally isolated.
1998, 16(1): 38-47
Abstract:
The methacrylate monomers bearing mesogenic group and heterocyclicazo dye have been synthesized. The monomeric dye was copolymerized with the mesogenicmonomer using a free radical initiator to produce polymers useful for nonlinear optics. Themonomers and polymers were characterized by IR, 1H-NMR, and UV-Vis spectra. Theaverage molecular weight (Mw and Mn) of the polymers were determined by gel permeationchromatography. The thermal properties of the polymers such as thermal stability and phase transition behavior were studied by thermogravimetric analysis,differential thermal analysis,polarizing optical microscope and X-ray diffractometer.The results demonstrate that the synthesized polymers are crystalline polymers at room temperature and no liquid crystalline phases were observed for all of them.
The methacrylate monomers bearing mesogenic group and heterocyclicazo dye have been synthesized. The monomeric dye was copolymerized with the mesogenicmonomer using a free radical initiator to produce polymers useful for nonlinear optics. Themonomers and polymers were characterized by IR, 1H-NMR, and UV-Vis spectra. Theaverage molecular weight (Mw and Mn) of the polymers were determined by gel permeationchromatography. The thermal properties of the polymers such as thermal stability and phase transition behavior were studied by thermogravimetric analysis,differential thermal analysis,polarizing optical microscope and X-ray diffractometer.The results demonstrate that the synthesized polymers are crystalline polymers at room temperature and no liquid crystalline phases were observed for all of them.
1998, 16(1): 48-55
Abstract:
A series of main chain liquid crystal aromatic copolyesters with X-shapedand rod-shaped mesogenic units were synthesized via solution condensation polymerizationsof 4, 4'-(α,ω-octanedioyloxy)-dibenzoyl dichlorides with 2,5-bis(p-octanoxy benzoyloxy)-hydroquinone and diphenol. All of the copolyesters showed thermotropic liquid crystallinebehaviors through observations using DSC, polarized microscopy and X-ray diffraction.The melting point (Tm) and the isotropization temperature (Ti) change regularly with varying the content of diphenol unit in the copolymers.
A series of main chain liquid crystal aromatic copolyesters with X-shapedand rod-shaped mesogenic units were synthesized via solution condensation polymerizationsof 4, 4'-(α,ω-octanedioyloxy)-dibenzoyl dichlorides with 2,5-bis(p-octanoxy benzoyloxy)-hydroquinone and diphenol. All of the copolyesters showed thermotropic liquid crystallinebehaviors through observations using DSC, polarized microscopy and X-ray diffraction.The melting point (Tm) and the isotropization temperature (Ti) change regularly with varying the content of diphenol unit in the copolymers.
1998, 16(1): 56-61
Abstract:
Propylene was polymerized with a novel supported Ziegler-Natta catalystcontaining 2,2-di-iso-butyl-1,3-dimethoxy-propane (DIBDMP) as internal donor and in theabsence of external donor. The tacticity distribution of polypropylene was obtained by usingtemperature rising elution fractionation (TREF) technique and microstructure of fractionswas studied with 13C-NMR. Compared with the catalyst without electron donor, this cat-alyst gives a considerably narrower tacticity distribution. Fractionation data demonstrate that DIBDMP shows better performance than aromatic diester DNBP (di-n-butyl phthalate).Chemically inverted propylene units and less stereoblockiness are found in the first fraction.Possible reasons for these were presented.
Propylene was polymerized with a novel supported Ziegler-Natta catalystcontaining 2,2-di-iso-butyl-1,3-dimethoxy-propane (DIBDMP) as internal donor and in theabsence of external donor. The tacticity distribution of polypropylene was obtained by usingtemperature rising elution fractionation (TREF) technique and microstructure of fractionswas studied with 13C-NMR. Compared with the catalyst without electron donor, this cat-alyst gives a considerably narrower tacticity distribution. Fractionation data demonstrate that DIBDMP shows better performance than aromatic diester DNBP (di-n-butyl phthalate).Chemically inverted propylene units and less stereoblockiness are found in the first fraction.Possible reasons for these were presented.
1998, 16(1): 62-66
Abstract:
In this work, influence of molecular weight and periodate modification ofβ-D-glucans isolated from Poria cocos sclerotium on the antitumor activities against Sar-coma 180 and Ehrlich ascites carcinoma (EAC) tumor was studied. The results show thattwo glucans PC3 (linear β-(1→3)-D-glucan) and PC4 [β-(1→3)-D-glucan with a fewof branches and glucuronic acid] are devoid of antitumor activity. However, when theglucans were modified by periodate oxidation, borohydride reduction and mild hydrolysis or partially hydrolysis,the derivatives have obvious antitumor activities.The decrease in molecular weight of glucans after periodate modification hardly affects their antitumor actions,but on the other hand,the decrease of molecular weight without periodate modification could lead to an enhancement of the antitumor activities.Moreover,the glucans and these derivatives have much higher enhancement ratios of body weight of mice than that of --Fluorouracil (5-Fu),suggesting that they are less toxic than 5-Fu.
In this work, influence of molecular weight and periodate modification ofβ-D-glucans isolated from Poria cocos sclerotium on the antitumor activities against Sar-coma 180 and Ehrlich ascites carcinoma (EAC) tumor was studied. The results show thattwo glucans PC3 (linear β-(1→3)-D-glucan) and PC4 [β-(1→3)-D-glucan with a fewof branches and glucuronic acid] are devoid of antitumor activity. However, when theglucans were modified by periodate oxidation, borohydride reduction and mild hydrolysis or partially hydrolysis,the derivatives have obvious antitumor activities.The decrease in molecular weight of glucans after periodate modification hardly affects their antitumor actions,but on the other hand,the decrease of molecular weight without periodate modification could lead to an enhancement of the antitumor activities.Moreover,the glucans and these derivatives have much higher enhancement ratios of body weight of mice than that of --Fluorouracil (5-Fu),suggesting that they are less toxic than 5-Fu.
1998, 16(1): 67-74
Abstract:
Using Nd:YAG second harmonic pulse (100 ps), the optical storage proper-ties of two novel polyesters, poly [4'-bis (N, N-oxyethylene) imino-4-nitroazobenzene suc-cinyl] and poly [2'-chloro-4'-bis (N, N-oxyethylene) iminth-4-nitroazobenzene succiny] havebeen studied by multiwave mixing. The high-order diffractions of the orientation gratingsinduced by anisotropy via the reorientation of nitroazobenzene groups and optical infor-mation storage with long-term stability have been realized by multiwave mixing in their films.Up to 3rd order forward diffraction was detected in two wave mixing,while up to 4th order backward diffraction was observed in degenerated four wave mixing.The recording mechanism was explained by the trans-cis-trans isomerization cycles of azobenzene groups.The isomerization of these azobenzene gruops probably undergoes with inversion mechanism under the experimental conditions.The information recorded in these films has been kept for more than 6 months.
Using Nd:YAG second harmonic pulse (100 ps), the optical storage proper-ties of two novel polyesters, poly [4'-bis (N, N-oxyethylene) imino-4-nitroazobenzene suc-cinyl] and poly [2'-chloro-4'-bis (N, N-oxyethylene) iminth-4-nitroazobenzene succiny] havebeen studied by multiwave mixing. The high-order diffractions of the orientation gratingsinduced by anisotropy via the reorientation of nitroazobenzene groups and optical infor-mation storage with long-term stability have been realized by multiwave mixing in their films.Up to 3rd order forward diffraction was detected in two wave mixing,while up to 4th order backward diffraction was observed in degenerated four wave mixing.The recording mechanism was explained by the trans-cis-trans isomerization cycles of azobenzene groups.The isomerization of these azobenzene gruops probably undergoes with inversion mechanism under the experimental conditions.The information recorded in these films has been kept for more than 6 months.
1998, 16(1): 75-80
Abstract:
The structure and properties of poly(N-vinylcarbazole) (PVCZ) obtainedvia asymmetrically stereoselective polymerization have been studied by using 1HNMRspectra, UV spectra, DSC analysis and GPC. The steric microstructure i.e. the contentof isotactic sequences was found to be increased by using AIBN to (-)Sp+(+)CSA- asthe initiators or catalysts and the mole extinction coefficient to be decreased. Bimodalmolecular weight distribution (MWD)s of the obtained PVCZs were caused by two propa-gating species of the free ions and the ion-pairs associated with the organic salts during polymerization.
The structure and properties of poly(N-vinylcarbazole) (PVCZ) obtainedvia asymmetrically stereoselective polymerization have been studied by using 1HNMRspectra, UV spectra, DSC analysis and GPC. The steric microstructure i.e. the contentof isotactic sequences was found to be increased by using AIBN to (-)Sp+(+)CSA- asthe initiators or catalysts and the mole extinction coefficient to be decreased. Bimodalmolecular weight distribution (MWD)s of the obtained PVCZs were caused by two propa-gating species of the free ions and the ion-pairs associated with the organic salts during polymerization.
1998, 16(1): 81-85
Abstract:
A series of thermotropic liquid crystalline polyesteramides with differ-ent sequence structure based on dimethylbenzidine (DMBD), bisphenol-A(BPA) and p-terephthalyl chloride (TPC) was synthesized by changing the feeding order of monomers inlow temperature solution polycondensation system. By means of NMR and a computer pro-gram the sequence structure parameters were measured. The effect of sequence structureon liquid crystalline phase transition temperature of PEAs obtained was investigated.
A series of thermotropic liquid crystalline polyesteramides with differ-ent sequence structure based on dimethylbenzidine (DMBD), bisphenol-A(BPA) and p-terephthalyl chloride (TPC) was synthesized by changing the feeding order of monomers inlow temperature solution polycondensation system. By means of NMR and a computer pro-gram the sequence structure parameters were measured. The effect of sequence structureon liquid crystalline phase transition temperature of PEAs obtained was investigated.
1998, 16(1): 86-90
Abstract:
By means of a vacuum time-lag method, gas transport properties of apolyimide based on 2, 2- bis (3, 4- decarboxyphenyl ) hexafluoropropane dianhydride (6FDA )and meta- phenylenediamine (mPDA ) have been measured as a function of upstream pres-sure and temperature. The results show that no gas-induced plasticization occurs for thispolyimide in the upstream pressure range from 1 atm to 20atm. The temperature depen-dence of P and D can be described by the Arrhenius equations. The activation energies of permeation and diffusion were obtained for the gas/polymer pair studied and correlated with the size of penetrant gas.
By means of a vacuum time-lag method, gas transport properties of apolyimide based on 2, 2- bis (3, 4- decarboxyphenyl ) hexafluoropropane dianhydride (6FDA )and meta- phenylenediamine (mPDA ) have been measured as a function of upstream pres-sure and temperature. The results show that no gas-induced plasticization occurs for thispolyimide in the upstream pressure range from 1 atm to 20atm. The temperature depen-dence of P and D can be described by the Arrhenius equations. The activation energies of permeation and diffusion were obtained for the gas/polymer pair studied and correlated with the size of penetrant gas.
1998, 16(1): 91-96
Abstract:
The meso- tetraarylporphyrin has been anchored to styrene- divinylbenzenecopolymers by reaction of meso- tetra (4-hydroxylphenyl ) porphyrin with chloromethylatedresin under mild condition. A number of polymer transition metal complexes have beenprepared with the polymer ligand and metal salts. The polymeric ligand and its complexeshave been characterized by electronic spectra, and vibrational spectra. Cyclohexene can behydrogenated with the polymeric porphyrin palladium complex(P-THPPPd) as catalyst,and its catalytic activity was influenced by the polarity of solvents,the contents of water in ethanol or reaction temperature.However,its catalytic activity was lower for intro groups,carbonyl groups and olefins with steric hindrance substityents,and showed no activity for aromatic rings under these conditions.
The meso- tetraarylporphyrin has been anchored to styrene- divinylbenzenecopolymers by reaction of meso- tetra (4-hydroxylphenyl ) porphyrin with chloromethylatedresin under mild condition. A number of polymer transition metal complexes have beenprepared with the polymer ligand and metal salts. The polymeric ligand and its complexeshave been characterized by electronic spectra, and vibrational spectra. Cyclohexene can behydrogenated with the polymeric porphyrin palladium complex(P-THPPPd) as catalyst,and its catalytic activity was influenced by the polarity of solvents,the contents of water in ethanol or reaction temperature.However,its catalytic activity was lower for intro groups,carbonyl groups and olefins with steric hindrance substityents,and showed no activity for aromatic rings under these conditions.
