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2002 Volume 20 Issue 5
2002, 20(5): 397-400
Abstract:
A star-shaped compound of perfluoro-1-octanesulfonated fullerene was synthesized. The measurement of thefriction for its spin-coating film by friction force microscopy (FFM) reveals that the films possess lower friction forcecompared to that of the star-shaped C60-polystyene films.
A star-shaped compound of perfluoro-1-octanesulfonated fullerene was synthesized. The measurement of thefriction for its spin-coating film by friction force microscopy (FFM) reveals that the films possess lower friction forcecompared to that of the star-shaped C60-polystyene films.
2002, 20(5): 401-407
Abstract:
Four new rod-coil diblock molecules, which had well-defined para-phenylene oligomers (PPP, from biphenyl toquinquephenyl) as rigid segments and poly(ethylene oxide) (PEO, Mw ca. 750) as flexible segments, were synhesized. Thechemical structure and the number of repeating unit in PEO coil and PPP rod were characterized by 1H-NMR and MALDI-TOF mass spectromeny. The diblock oligomers showed good solubility in common organic solvents and aggregated in water as characterized by a blue shift in UV-vis absorption spectra,a red shift in emission spectra,quenching of the fluorescence and formation of the microfibrilla and fractal-like structures.The formation of different supramolecular structure meant that this effort might lead to commercial important highly organized functional materials.
Four new rod-coil diblock molecules, which had well-defined para-phenylene oligomers (PPP, from biphenyl toquinquephenyl) as rigid segments and poly(ethylene oxide) (PEO, Mw ca. 750) as flexible segments, were synhesized. Thechemical structure and the number of repeating unit in PEO coil and PPP rod were characterized by 1H-NMR and MALDI-TOF mass spectromeny. The diblock oligomers showed good solubility in common organic solvents and aggregated in water as characterized by a blue shift in UV-vis absorption spectra,a red shift in emission spectra,quenching of the fluorescence and formation of the microfibrilla and fractal-like structures.The formation of different supramolecular structure meant that this effort might lead to commercial important highly organized functional materials.
2002, 20(5): 409-412
Abstract:
Poly(N, N-dimethylaminoethyl methacrylate) (polyDMAEMA) hydrogels prepared by γ-irradiation showed obvioustemperature-sensitivity in a temperature range of 38-40℃ and pH-sensitivity at pH = 2.5. They also showed clectric responsebehavior although it was not typical. The hydrogels were used in controlled release at different pH, temperature, and electricvoltage. The release rates of methylene blue (MB) from the gels at 52℃ and pH = 1.24 were fatter than those at 20℃ and pH= 10.56, respectively. In addition,the release rate at a field voltage of 5.0 was also faster than that without electric field.
Poly(N, N-dimethylaminoethyl methacrylate) (polyDMAEMA) hydrogels prepared by γ-irradiation showed obvioustemperature-sensitivity in a temperature range of 38-40℃ and pH-sensitivity at pH = 2.5. They also showed clectric responsebehavior although it was not typical. The hydrogels were used in controlled release at different pH, temperature, and electricvoltage. The release rates of methylene blue (MB) from the gels at 52℃ and pH = 1.24 were fatter than those at 20℃ and pH= 10.56, respectively. In addition,the release rate at a field voltage of 5.0 was also faster than that without electric field.
2002, 20(5): 413-417
Abstract:
The copolymerization of DL-LA and 3-BMG was carried out in bulk with Stannous 2-ethylhexanoate as thecatalyst. A series of copolymers with pendant protected groups were obtained and characterized by 1H-NMR and GPCanalysis. The monomer reactivity ratios were evaluated by the Fineman-Ross method and the Kelen-Tudos method and foundto be rBMG = 1.96 and rLA = 0.37, respectively.
The copolymerization of DL-LA and 3-BMG was carried out in bulk with Stannous 2-ethylhexanoate as thecatalyst. A series of copolymers with pendant protected groups were obtained and characterized by 1H-NMR and GPCanalysis. The monomer reactivity ratios were evaluated by the Fineman-Ross method and the Kelen-Tudos method and foundto be rBMG = 1.96 and rLA = 0.37, respectively.
2002, 20(5): 419-423
Abstract:
Electrochemical impedance spectroscopy (EIS) was first used for the characterization of polyfuran (PFu) films thathad been formed electrochemically on an Au electrode. The polyfuran was measured in high oxidation state, intermediateoxidation state and reduction state, respectively. As the oxidation level is increased, the ionic conductivity of PFu/BF4-increases. And impedance studies on PFu show that the anion BF4- appears to be mobile with a high diffusion coefficient of approximately 10-8 cm2·s-1.
Electrochemical impedance spectroscopy (EIS) was first used for the characterization of polyfuran (PFu) films thathad been formed electrochemically on an Au electrode. The polyfuran was measured in high oxidation state, intermediateoxidation state and reduction state, respectively. As the oxidation level is increased, the ionic conductivity of PFu/BF4-increases. And impedance studies on PFu show that the anion BF4- appears to be mobile with a high diffusion coefficient of approximately 10-8 cm2·s-1.
2002, 20(5): 425-430
Abstract:
The Raman spectra of poly(3-methylthiophene) (PMeT) films with different thicknesses, which have beenelectrochemically deposited on a flat stainless steel electrode surface by direct oxidation of 3-methylthiophene in borontrifluoride diethyl etherate (BFEE) at a constant applied potential of 1.38 V (versus SCE), have been investigated byexcitation with a 633-nm laser beam. The spectroscopic results demonstrated that the doping level of PMeT film was increasing during film growth. This finding was also confirmed by electrochemical examination.Moreover,the Raman bands assigned to radical cations and dications in deped PMeT films were found approximately at 1420 and 1400 cm-1,respectively.Radical cations and dications coexist on the backbone of PMeT as conductive species and their concentrations increase with the increase of doping level.Successive cyclic voltammetry was proved to be an effective approach to improving the doping level of as-grown thin compact PMeT film.
The Raman spectra of poly(3-methylthiophene) (PMeT) films with different thicknesses, which have beenelectrochemically deposited on a flat stainless steel electrode surface by direct oxidation of 3-methylthiophene in borontrifluoride diethyl etherate (BFEE) at a constant applied potential of 1.38 V (versus SCE), have been investigated byexcitation with a 633-nm laser beam. The spectroscopic results demonstrated that the doping level of PMeT film was increasing during film growth. This finding was also confirmed by electrochemical examination.Moreover,the Raman bands assigned to radical cations and dications in deped PMeT films were found approximately at 1420 and 1400 cm-1,respectively.Radical cations and dications coexist on the backbone of PMeT as conductive species and their concentrations increase with the increase of doping level.Successive cyclic voltammetry was proved to be an effective approach to improving the doping level of as-grown thin compact PMeT film.
2002, 20(5): 431-437
Abstract:
The kinetics of I→N transition of a side chain nematic polymethacrylate has been studied by small angledepolarized light scattering intensity measurements using a charge coupled device linear image sensor. The polymer showsthe transition temperatures K52N79I in ℃. The Hv scattering intensity J(q,t) during the transition I (at 80.2℃)→N (at75.8℃) shows that J(q) is independent of q for all t, and during the initial stage (in 6 s) J(t) increases exponentially with t.In the later stage of the transition (t) approaches a saturation value in 2 min.This experimental result indicates that the I→N transition of a liquid crystalline polymer is a spinodal type of phase transition mediated by orientation fluctuation.
The kinetics of I→N transition of a side chain nematic polymethacrylate has been studied by small angledepolarized light scattering intensity measurements using a charge coupled device linear image sensor. The polymer showsthe transition temperatures K52N79I in ℃. The Hv scattering intensity J(q,t) during the transition I (at 80.2℃)→N (at75.8℃) shows that J(q) is independent of q for all t, and during the initial stage (in 6 s) J(t) increases exponentially with t.In the later stage of the transition (t) approaches a saturation value in 2 min.This experimental result indicates that the I→N transition of a liquid crystalline polymer is a spinodal type of phase transition mediated by orientation fluctuation.
2002, 20(5): 439-444
Abstract:
The adsorption of aniline, N-methylaniline and N,N-dimethylaniline onto carboxyl resin in Cu2+ form from water,ethanol and n-hexane have been studied. The results show that the adsorption affinities from n-hexane are higher than thatfrom water, and nearly zero from ethanol. The separation factors for the adsorption of these three amines from mixed solutionwere also examined. The results of continuous column operations show that the breakthrough capacity of aniline from n-hexane reaches 90 mg/g dry resin in Cu2+ form,and the amines adsorbed can be stripped with anhydrous ethanol effectively.Adsorption onto carboxyl resin in Cu2+ form from non-aqueous medium and desorption with anhydrous eluant can overcome the run-off of Cu2+ from the resin,and would show potential advantages in the separation of some water-insoluble natural products.
The adsorption of aniline, N-methylaniline and N,N-dimethylaniline onto carboxyl resin in Cu2+ form from water,ethanol and n-hexane have been studied. The results show that the adsorption affinities from n-hexane are higher than thatfrom water, and nearly zero from ethanol. The separation factors for the adsorption of these three amines from mixed solutionwere also examined. The results of continuous column operations show that the breakthrough capacity of aniline from n-hexane reaches 90 mg/g dry resin in Cu2+ form,and the amines adsorbed can be stripped with anhydrous ethanol effectively.Adsorption onto carboxyl resin in Cu2+ form from non-aqueous medium and desorption with anhydrous eluant can overcome the run-off of Cu2+ from the resin,and would show potential advantages in the separation of some water-insoluble natural products.
2002, 20(5): 445-451
Abstract:
Atom transfer radical polymerization (ATRP) of styrene catalyzed by cuprous (CuX)/1, 10-phenanthroline (Phen)and CuX/CuX2/Phen was conducted in an aqueous dispersed system. A stable latex was obtained by using ionic surfactantsodium lauryl sulfonate (SLS) or composite surfactants, such as SLS/polyoxyethylene nonyl phenyl ether (OP-10),SLS/hexadecanol and SLS/OP-10/hexadecanol. Among which SLS and SLS/OP-10/hexadecanol systems established betterdispersed effect during the polymerization. It was found that Phen was a more syitable ligand than N,N,N′N″,N″-pentamethyldiethylenetriamine(PMDETA) to maintain an appropriate equilibrium of the activator Cu(I) and the deactivator Cu(II) between the organic phase and the water phase.The effect of several initiators(such as EBiB,CCl4 and 1-PEBr) and the temperature on such a kind of ATRP system was also observed.The number-average molar mass(Mn) of polystyrene(PS) increased with the conversion and the molar mass distribution (mw/Mn) remained narrow.These experimental data show that the polymerization could be controlled except for the quick increase of monomer conversion and the number-average molar mass of PS in the initial stage of polymerization.Furthermore,the initiator efficiency was found to be low(～57%) in CuX/Phen catalyzed system.To overcome this problem,Cu(II) X2(20 mol%-50 mol% based on CuX) was introduced into the polymerization system.In this case,higher initiator efficiency (60%-90%),low Mw/Mn of PS (as low as 1.08) were achieved and the molar masses of the PS fit with the theoretical ones.
Atom transfer radical polymerization (ATRP) of styrene catalyzed by cuprous (CuX)/1, 10-phenanthroline (Phen)and CuX/CuX2/Phen was conducted in an aqueous dispersed system. A stable latex was obtained by using ionic surfactantsodium lauryl sulfonate (SLS) or composite surfactants, such as SLS/polyoxyethylene nonyl phenyl ether (OP-10),SLS/hexadecanol and SLS/OP-10/hexadecanol. Among which SLS and SLS/OP-10/hexadecanol systems established betterdispersed effect during the polymerization. It was found that Phen was a more syitable ligand than N,N,N′N″,N″-pentamethyldiethylenetriamine(PMDETA) to maintain an appropriate equilibrium of the activator Cu(I) and the deactivator Cu(II) between the organic phase and the water phase.The effect of several initiators(such as EBiB,CCl4 and 1-PEBr) and the temperature on such a kind of ATRP system was also observed.The number-average molar mass(Mn) of polystyrene(PS) increased with the conversion and the molar mass distribution (mw/Mn) remained narrow.These experimental data show that the polymerization could be controlled except for the quick increase of monomer conversion and the number-average molar mass of PS in the initial stage of polymerization.Furthermore,the initiator efficiency was found to be low(～57%) in CuX/Phen catalyzed system.To overcome this problem,Cu(II) X2(20 mol%-50 mol% based on CuX) was introduced into the polymerization system.In this case,higher initiator efficiency (60%-90%),low Mw/Mn of PS (as low as 1.08) were achieved and the molar masses of the PS fit with the theoretical ones.
2002, 20(5): 453-459
Abstract:
Copolymerization of propylene oxide (PO) and ethylene oxide (EO) using double metal cyanide (DMC) complexas the catalyst was carried out. The structure of random copolymers was confirmed by 13C-NMR and IR spectra. 1H-NMRanalysis shows that the EO content in the copolymer is the same as that in the initial monomer feed. Moderate molecularweight copolymers with various EO content were obtained and their values of molecular weigh distribution (MWD) fell inthe range of 1.21-1.55. It was found that the molecular weight of copolymers is controlled by the mass ratio of EO+PO to initiator moles used.The reaction rate as well as polymer yield decrease with increasing EO content in the feed composition.
Copolymerization of propylene oxide (PO) and ethylene oxide (EO) using double metal cyanide (DMC) complexas the catalyst was carried out. The structure of random copolymers was confirmed by 13C-NMR and IR spectra. 1H-NMRanalysis shows that the EO content in the copolymer is the same as that in the initial monomer feed. Moderate molecularweight copolymers with various EO content were obtained and their values of molecular weigh distribution (MWD) fell inthe range of 1.21-1.55. It was found that the molecular weight of copolymers is controlled by the mass ratio of EO+PO to initiator moles used.The reaction rate as well as polymer yield decrease with increasing EO content in the feed composition.
2002, 20(5): 461-465
Abstract:
It was found that traces of water in the reaction medium would result in a great increase of gel and a decrease ofmolecular weight of the poly(2-methoxy, 5-(2'-ethylhexyloxy)-1, 4-phenylene vinylene) during the polymerization, whichultimately led to inferior film qualities and device properties. The device (ITO/PEDOT/MEH-PPV/Ba/Al) with MEH-PPVprepared under dry conditions has an external quantum efficiency of above 2.0%.
It was found that traces of water in the reaction medium would result in a great increase of gel and a decrease ofmolecular weight of the poly(2-methoxy, 5-(2'-ethylhexyloxy)-1, 4-phenylene vinylene) during the polymerization, whichultimately led to inferior film qualities and device properties. The device (ITO/PEDOT/MEH-PPV/Ba/Al) with MEH-PPVprepared under dry conditions has an external quantum efficiency of above 2.0%.
2002, 20(5): 467-472
Abstract:
The interaction between poly(methymethacrylate) (PMMA) and poly(vinyl chloride) (PVC) has been studied indilute urea solutions of dimethylformamide (DMF) at 28℃ using a dilute solution viscometry method. The results show thatthe polymer mixtures are compatible in DMF solution in the absence of urea. The influence of urea addition on the degree ofcompatibility of the polymer mixtures has been studied in terms of the compatibility parameters (△bm and △[η]m). It was found that the compatibility of the polymer mixtures is decreased with increasing urea addition,passing through a minimum at 0.5 M urea.
The interaction between poly(methymethacrylate) (PMMA) and poly(vinyl chloride) (PVC) has been studied indilute urea solutions of dimethylformamide (DMF) at 28℃ using a dilute solution viscometry method. The results show thatthe polymer mixtures are compatible in DMF solution in the absence of urea. The influence of urea addition on the degree ofcompatibility of the polymer mixtures has been studied in terms of the compatibility parameters (△bm and △[η]m). It was found that the compatibility of the polymer mixtures is decreased with increasing urea addition,passing through a minimum at 0.5 M urea.
2002, 20(5): 473-480
Abstract:
The impact properties of two selected metallocene-catalyzed ethylene-butene copolymers and one conventionalcopolymer were evaluated using Izod impact test. It is found that the metallocene-catalyzed copolymer shows superior impactproperties. This result was explained on the basis of the more homogeneous inter-molecular composition distribution andnarrower molecular weight distribution, which leads to more homogeneous morphology with fewer defects. Stepwise crystallization improves the impact properties,especially in the crack propagation process,to a large extent.This is due to the decrease of entanglements by stepwise crystallization,which is advantageous for the chain slip and shear.The polymer with heterogeneous intra-molecular composition distribution exhibits a more evident improvement of impact properties under stepwise crystallization.
The impact properties of two selected metallocene-catalyzed ethylene-butene copolymers and one conventionalcopolymer were evaluated using Izod impact test. It is found that the metallocene-catalyzed copolymer shows superior impactproperties. This result was explained on the basis of the more homogeneous inter-molecular composition distribution andnarrower molecular weight distribution, which leads to more homogeneous morphology with fewer defects. Stepwise crystallization improves the impact properties,especially in the crack propagation process,to a large extent.This is due to the decrease of entanglements by stepwise crystallization,which is advantageous for the chain slip and shear.The polymer with heterogeneous intra-molecular composition distribution exhibits a more evident improvement of impact properties under stepwise crystallization.
2002, 20(5): 481-483
Abstract:
Exfoliated polyurethane/montmorillonite nanocomposites with both high elongation at break and high tensilestrength were studied by dynamic-infrared spectroscopy (dynamic-IR). The results show that crystallization induced byadditional stress is impeded by the nano-layered organo montmorillonite.
Exfoliated polyurethane/montmorillonite nanocomposites with both high elongation at break and high tensilestrength were studied by dynamic-infrared spectroscopy (dynamic-IR). The results show that crystallization induced byadditional stress is impeded by the nano-layered organo montmorillonite.
