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2014 Volume 32 Issue 7
Self-assembly Behavior of Copolymers with Super Segregated Structure Containing Fluorinated Segments
2014, 32(7): 817-822
doi: 10.1007/s10118-014-1476-z
Abstract:
Copolymers with super segregated structure of hydrophilic methoxy poly(ethylene glycol) (mPEG) and fluorophilic poly(1H,1H,2H,2H-perfluorodecyl acrylate) (PFA) were prepared. And just because of this super segregated structure which was resulted from the extremely strong incompatibility between the two blocks, several interesting self-assembly behaviors of the copolymers were displayed and studied under different conditions. Transmission electron microscope (TEM) showed that with the increase of PFA in the polymerization system, the incompatibility in this super segregated structure became stronger, and the self-assembly behavior changed from ball-like or rod-like to vesicles, and finally collapsed to sheet-like. The self-assembly behavior changed likewise when the initial concentration increased. And the interesting formation of these barrel-like and spindle-like vesicles was finally studied with different cooling speeds. It's finally found that with this super segregation structure, these new self-assembly morphology might be formed due to the extremely strong incompatibility between mPEG and PFA segments.
Copolymers with super segregated structure of hydrophilic methoxy poly(ethylene glycol) (mPEG) and fluorophilic poly(1H,1H,2H,2H-perfluorodecyl acrylate) (PFA) were prepared. And just because of this super segregated structure which was resulted from the extremely strong incompatibility between the two blocks, several interesting self-assembly behaviors of the copolymers were displayed and studied under different conditions. Transmission electron microscope (TEM) showed that with the increase of PFA in the polymerization system, the incompatibility in this super segregated structure became stronger, and the self-assembly behavior changed from ball-like or rod-like to vesicles, and finally collapsed to sheet-like. The self-assembly behavior changed likewise when the initial concentration increased. And the interesting formation of these barrel-like and spindle-like vesicles was finally studied with different cooling speeds. It's finally found that with this super segregation structure, these new self-assembly morphology might be formed due to the extremely strong incompatibility between mPEG and PFA segments.
2014, 32(7): 823-833
doi: 10.1007/s10118-014-1474-1
Abstract:
In this study, four hydroxyl-terminated polydimethylsiloxanes (PDMSOH) with different viscosities and hydroxyl contents were used to improve the toughness of polycarbonate (PC) through reactive melt blending. A largely improved toughness of PC has been achieved, and the low temperature toughness of PC/PDMSOH blends could overtake that of PC homopolymer in much higher temperatures (e.g. -10 ℃ versus 23 ℃). Moreover, it was found that the more the hydroxyl content, the less the PDMSOH was needed to reach the highest toughness, suggesting that equivalent molar ratio between the carbonyl group content of PC and the hydroxyl group content of PDMSOH was required for the toughening of PC. Ultraviolet spectrophotometry was used to analyze the possible reaction between PC and PDMSOH. Contact angle was measured to assess the change of interfacial interaction between PC and PDMSOH as change of viscosity and hydroxyl content. The formation of PC-co-PDMSOH copolymer was believed to be the key for the toughening effect. This work gives a profound recommendation of the optimum kind and dosage of PDMSOH which should be used to improve the toughness of PC and will find immediate industrial applications.
In this study, four hydroxyl-terminated polydimethylsiloxanes (PDMSOH) with different viscosities and hydroxyl contents were used to improve the toughness of polycarbonate (PC) through reactive melt blending. A largely improved toughness of PC has been achieved, and the low temperature toughness of PC/PDMSOH blends could overtake that of PC homopolymer in much higher temperatures (e.g. -10 ℃ versus 23 ℃). Moreover, it was found that the more the hydroxyl content, the less the PDMSOH was needed to reach the highest toughness, suggesting that equivalent molar ratio between the carbonyl group content of PC and the hydroxyl group content of PDMSOH was required for the toughening of PC. Ultraviolet spectrophotometry was used to analyze the possible reaction between PC and PDMSOH. Contact angle was measured to assess the change of interfacial interaction between PC and PDMSOH as change of viscosity and hydroxyl content. The formation of PC-co-PDMSOH copolymer was believed to be the key for the toughening effect. This work gives a profound recommendation of the optimum kind and dosage of PDMSOH which should be used to improve the toughness of PC and will find immediate industrial applications.
2014, 32(7): 834-843
doi: 10.1007/s10118-014-1472-3
Abstract:
Surface modified rutile-type titanium dioxide (CST) nanorods were used as a UV absorber in polypropylene (PP) thick bars in combination with the hindered amine light stabilizer (HALS) Chimassorb 944 (C944). For all of the tested samples, the photodegradation was mainly limited in the region near the exposed surface, as proved by the carbonyl index and molecular weight. Compared with the typical HALS photostabilization system containing organic hindered phenol UV absorber Tinuvin 328 (T328), the thickness of photodegradation region for PP/C944/CST was only a quarter to that for PP/C944 and PP/C944/T328, while the rates of reduction in molecular weight and increase in carbonyl index were much lower. Optical microscopic observation showed that the evolution of surface micro-cracks in PP/C944/CST was quite different from that in the other samples, while scanning electronic micrographs revealed that the depth of the micro-cracks in PP/C944/CST was much shorter than that in the others. It is therefore concluded that the protection of CST on PP thick bars is mainly attributed to the outstanding UV-shielding and cracks-blocking abilities.
Surface modified rutile-type titanium dioxide (CST) nanorods were used as a UV absorber in polypropylene (PP) thick bars in combination with the hindered amine light stabilizer (HALS) Chimassorb 944 (C944). For all of the tested samples, the photodegradation was mainly limited in the region near the exposed surface, as proved by the carbonyl index and molecular weight. Compared with the typical HALS photostabilization system containing organic hindered phenol UV absorber Tinuvin 328 (T328), the thickness of photodegradation region for PP/C944/CST was only a quarter to that for PP/C944 and PP/C944/T328, while the rates of reduction in molecular weight and increase in carbonyl index were much lower. Optical microscopic observation showed that the evolution of surface micro-cracks in PP/C944/CST was quite different from that in the other samples, while scanning electronic micrographs revealed that the depth of the micro-cracks in PP/C944/CST was much shorter than that in the others. It is therefore concluded that the protection of CST on PP thick bars is mainly attributed to the outstanding UV-shielding and cracks-blocking abilities.
2014, 32(7): 844-853
doi: 10.1007/s10118-014-1458-1
Abstract:
Four new low-band-gap alternating copolymers (P-1, P-2, P-3 and P-4) based on electron-rich benzodithiophene and newly developed electron-deficient units, thienopyrazine or dithiadiazatrindene derivatives, were synthesized by Stille polycondensation. All polymers exhibit good solubility in common organic solvents and a broad absorption band in the visible to near-infrared regions. The film optical band gaps of the polymers are in the range of 1.28-2.07 eV and the highest occupied molecular orbital (HOMO) energy levels are in the range of -4.99 eV to -5.28 eV. Bulk heterojunction polymer solar cells (PSCs) of the polymers were fabricated with phenyl-C61-butyric acid methyl ester (PC61BM) as acceptor material, and a power conversion efficiency of 0.80% was realized with P-1 as donor material.
Four new low-band-gap alternating copolymers (P-1, P-2, P-3 and P-4) based on electron-rich benzodithiophene and newly developed electron-deficient units, thienopyrazine or dithiadiazatrindene derivatives, were synthesized by Stille polycondensation. All polymers exhibit good solubility in common organic solvents and a broad absorption band in the visible to near-infrared regions. The film optical band gaps of the polymers are in the range of 1.28-2.07 eV and the highest occupied molecular orbital (HOMO) energy levels are in the range of -4.99 eV to -5.28 eV. Bulk heterojunction polymer solar cells (PSCs) of the polymers were fabricated with phenyl-C61-butyric acid methyl ester (PC61BM) as acceptor material, and a power conversion efficiency of 0.80% was realized with P-1 as donor material.
2014, 32(7): 854-863
doi: 10.1007/s10118-014-1470-5
Abstract:
This contribution reports ethylene polymerization behavior of titanium complexes incorporating bis(phenoxy-imine) ligands. Six phenoxy-imine Ti(IV) complexes {6-R1-2-[CH＝N(2,6-difluoro-3,5-diR2-4-R3Ph)]C6H3O}2TiCl2 (1: R1 = H, R2 = H, R3 = H; 2: R1 = H, R2 = H, R3 = 4-vinylphenyl; 3: R1 = CH3, R2 = H, R3 = H; 4: R1 = CH3, R2 = H, R3 = 4-vinylphenyl; 5: R1 = CH3, R2 = F, R3 = H; 6: R1 = CH3, R2 = F, R3 = 4-vinylphenyl) have been synthesized and evaluated for ethylene polymerization using dried MAO (simplified as DMAO) as cocatalyst. An obvious catalytic heterogeneity of Cat 2 (Complex 2/DMAO) towards ethylene polymerization was observed, which was illustrated by decreased activity, multi-modal molecular weight distribution and partially improved particle morphology comparing with Cat 1. Moreover, Cat 3 exhibits living characteristics in the process under certain conditions (25 ℃, less than 20 min). Otherwise, the moderate to high ethylene polymerization activity of ca. 105-106 g PE/(mol Tih) and high molecular weight (Mw = 105-106) of polyethylene can be obtained by changing the skeleton structure of these complexes.
This contribution reports ethylene polymerization behavior of titanium complexes incorporating bis(phenoxy-imine) ligands. Six phenoxy-imine Ti(IV) complexes {6-R1-2-[CH＝N(2,6-difluoro-3,5-diR2-4-R3Ph)]C6H3O}2TiCl2 (1: R1 = H, R2 = H, R3 = H; 2: R1 = H, R2 = H, R3 = 4-vinylphenyl; 3: R1 = CH3, R2 = H, R3 = H; 4: R1 = CH3, R2 = H, R3 = 4-vinylphenyl; 5: R1 = CH3, R2 = F, R3 = H; 6: R1 = CH3, R2 = F, R3 = 4-vinylphenyl) have been synthesized and evaluated for ethylene polymerization using dried MAO (simplified as DMAO) as cocatalyst. An obvious catalytic heterogeneity of Cat 2 (Complex 2/DMAO) towards ethylene polymerization was observed, which was illustrated by decreased activity, multi-modal molecular weight distribution and partially improved particle morphology comparing with Cat 1. Moreover, Cat 3 exhibits living characteristics in the process under certain conditions (25 ℃, less than 20 min). Otherwise, the moderate to high ethylene polymerization activity of ca. 105-106 g PE/(mol Tih) and high molecular weight (Mw = 105-106) of polyethylene can be obtained by changing the skeleton structure of these complexes.
2014, 32(7): 864-870
doi: 10.1007/s10118-014-1447-4
Abstract:
A novel highly porous 3-D poly(-caprolactone) (PCL) scaffold with micro-channels was fabricated by injection molding and diluent acetic acids leaching technologies. In this study, the chitosan fiber was employed to form the micro-channel in PCL matrix. The morphology, porosity and mechanical properties of the scaffolds were studied and calculated. It was found that the larger the content of chitosan fiber is, the higher the porosity would be, due to the volumetric expansion of chitosan fiber in PCL matrix during it being leached. In addition, the less the content of chitosan fiber is, the higher the compressive modulus would be.
A novel highly porous 3-D poly(-caprolactone) (PCL) scaffold with micro-channels was fabricated by injection molding and diluent acetic acids leaching technologies. In this study, the chitosan fiber was employed to form the micro-channel in PCL matrix. The morphology, porosity and mechanical properties of the scaffolds were studied and calculated. It was found that the larger the content of chitosan fiber is, the higher the porosity would be, due to the volumetric expansion of chitosan fiber in PCL matrix during it being leached. In addition, the less the content of chitosan fiber is, the higher the compressive modulus would be.
2014, 32(7): 871-879
doi: 10.1007/s10118-014-1461-6
Abstract:
A cyano-substituted diarylethlene derivative aggregation-induced emission (AIE) dye with two amino end-groups and 4,4'-(hexafluoroisopropylidene)diphthalic anhydride were facilely incorporated into red fluorescent organic nanoparticles (FONs) via room temperature anhydride ring-opening polymerization under an air atmosphere. These obtained RO-HFDA FONs were characterized by a series of techniques including gel permeation chromatography, Fourier transform infrared spectroscopy, size distribution and zeta potential measurements, UV-Vis absorption spectrum, fluorescent spectroscopy and transmission electron microscopy. Biocompatibility evaluation and cell uptake behavior of RO-HFDA FONs were further investigated to explore their potential biomedical application. We demonstrated that such FONs showed high water dispersibility, stable uniform spherical morphology (150-200 nm), broad excitation band (350-605 nm), intense red fluorescence (627 nm) and excellent biocompatibility, making them promising for cell imaging applications.
A cyano-substituted diarylethlene derivative aggregation-induced emission (AIE) dye with two amino end-groups and 4,4'-(hexafluoroisopropylidene)diphthalic anhydride were facilely incorporated into red fluorescent organic nanoparticles (FONs) via room temperature anhydride ring-opening polymerization under an air atmosphere. These obtained RO-HFDA FONs were characterized by a series of techniques including gel permeation chromatography, Fourier transform infrared spectroscopy, size distribution and zeta potential measurements, UV-Vis absorption spectrum, fluorescent spectroscopy and transmission electron microscopy. Biocompatibility evaluation and cell uptake behavior of RO-HFDA FONs were further investigated to explore their potential biomedical application. We demonstrated that such FONs showed high water dispersibility, stable uniform spherical morphology (150-200 nm), broad excitation band (350-605 nm), intense red fluorescence (627 nm) and excellent biocompatibility, making them promising for cell imaging applications.
2014, 32(7): 880-891
doi: 10.1007/s10118-014-1462-5
Abstract:
Surface-initiated atom transfer radical polymerization (SI-ATRP) was used to tether poly(2-dimethylaminoethyl methacrylate) (PDMAEMA) onto microporous PVDF membranes in order to synthesize membrane adsorbers for protein adsorption. The alkaline treatment and bromine addition reaction were used to anchor ATRP initiators on membrane surface. Then PDMAEMA was grafted from the membrane surface via SI-ATRP. Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) revealed the chemical composition and surface topography of the PVDF-g-PDMAEMA membrane surfaces. These results showed that PDMAEMA was grafted from the membrane surface successfully and a grafting yield as high as 1500 mg/cm2 was achieved. The effects of the grafting time and the density of initiators on the static and dynamic binding capacity of bovine serum albumin (BSA) were systematically investigated. Both the static and dynamic binding capacities increase with the bromination and polymerization time. However, the benefits of the initiator density on binding capacities are limited by the graft density of PDMAEMA chains.
Surface-initiated atom transfer radical polymerization (SI-ATRP) was used to tether poly(2-dimethylaminoethyl methacrylate) (PDMAEMA) onto microporous PVDF membranes in order to synthesize membrane adsorbers for protein adsorption. The alkaline treatment and bromine addition reaction were used to anchor ATRP initiators on membrane surface. Then PDMAEMA was grafted from the membrane surface via SI-ATRP. Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) revealed the chemical composition and surface topography of the PVDF-g-PDMAEMA membrane surfaces. These results showed that PDMAEMA was grafted from the membrane surface successfully and a grafting yield as high as 1500 mg/cm2 was achieved. The effects of the grafting time and the density of initiators on the static and dynamic binding capacity of bovine serum albumin (BSA) were systematically investigated. Both the static and dynamic binding capacities increase with the bromination and polymerization time. However, the benefits of the initiator density on binding capacities are limited by the graft density of PDMAEMA chains.
2014, 32(7): 892-905
doi: 10.1007/s10118-014-1457-2
Abstract:
A novel hydrophilic nanocomposite additive (TiO2-g-PNIPAAm) was synthesized by the surface modification of titanium dioxide (TiO2) with N-isopropylacrylamide (NIPAAm) via graft-from technique. And the nanocomposite membrane of poly(vinylidene fluoride) (PVDF)/TiO2-g-PNIPAAm was fabricated by wet phase inversion. The graft degree was obtained by thermo-gravimetric analysis (TGA). Fourier transform infrared attenuated reflection spectroscopy (FTIR-ATR) and X-ray photoelectronic spectroscopy (XPS) characterization results suggested that TiO2-g-PNIPAAm nanoparticles segregated on membrane surface during the phase separation process. Scanning electron microscopy (SEM) was conducted to investigate the surface and cross-section of the modified membranes. The water contact angle measurements confirmed that TiO2-g-PNIPAAm nanoparticles endowed PVDF membranes better hydrophlilicity and thermo-responsive properties compared with those of the pristine PVDF membrane. The water contact angle decreased from 92.8 of the PVDF membrane to 61.2 of the nanocompostie membrane. Bovine serum albumin (BSA) static and dynamic adsorption experiments suggested that excellent antifouling properties of membranes was acquired after adding TiO2-g-PNIPAAm. The maximum BSA adsorption at 40 ℃ was about 3 times than that at 23 ℃. The permeation experiments indicated the water flux recover ratio and BSA rejection ratio were improved at different temperatures.
A novel hydrophilic nanocomposite additive (TiO2-g-PNIPAAm) was synthesized by the surface modification of titanium dioxide (TiO2) with N-isopropylacrylamide (NIPAAm) via graft-from technique. And the nanocomposite membrane of poly(vinylidene fluoride) (PVDF)/TiO2-g-PNIPAAm was fabricated by wet phase inversion. The graft degree was obtained by thermo-gravimetric analysis (TGA). Fourier transform infrared attenuated reflection spectroscopy (FTIR-ATR) and X-ray photoelectronic spectroscopy (XPS) characterization results suggested that TiO2-g-PNIPAAm nanoparticles segregated on membrane surface during the phase separation process. Scanning electron microscopy (SEM) was conducted to investigate the surface and cross-section of the modified membranes. The water contact angle measurements confirmed that TiO2-g-PNIPAAm nanoparticles endowed PVDF membranes better hydrophlilicity and thermo-responsive properties compared with those of the pristine PVDF membrane. The water contact angle decreased from 92.8 of the PVDF membrane to 61.2 of the nanocompostie membrane. Bovine serum albumin (BSA) static and dynamic adsorption experiments suggested that excellent antifouling properties of membranes was acquired after adding TiO2-g-PNIPAAm. The maximum BSA adsorption at 40 ℃ was about 3 times than that at 23 ℃. The permeation experiments indicated the water flux recover ratio and BSA rejection ratio were improved at different temperatures.
2014, 32(7): 906-913
doi: 10.1007/s10118-014-1473-2
Abstract:
In this article tetrabutylammonium bromide (TBAB) was first added in buffer to compose a convenient and environmentally friendly system, and enzymatic polymerization of phenol catalyzed by horseradish peroxidase (HRP) could proceed efficiently in this system. When TBAB was added, the most conversion of phenol could reach 99.1%. The phenol polymer was considered to consist of a mixture of phenylene (Ph) and oxyphenylene (Ox) units by IR analysis, and the ratio of phenylene to oxyphenylene units (Ph/Ox) was measured by titration. Moreover, the effects of the dosage of horseradish peroxidase (HRP) and pH value on the conversion of phenol were investigated. The reaction performed very effectively in this novel system when the addition of HRP was only 0.2 mg. In all cases, the weight-average molecular weight calculated by GPC-SLS was in a range from 12000 Da to 30000 Da. The phenol polymer prepared in the present research possessed good thermal stability shown by TG analysis.
In this article tetrabutylammonium bromide (TBAB) was first added in buffer to compose a convenient and environmentally friendly system, and enzymatic polymerization of phenol catalyzed by horseradish peroxidase (HRP) could proceed efficiently in this system. When TBAB was added, the most conversion of phenol could reach 99.1%. The phenol polymer was considered to consist of a mixture of phenylene (Ph) and oxyphenylene (Ox) units by IR analysis, and the ratio of phenylene to oxyphenylene units (Ph/Ox) was measured by titration. Moreover, the effects of the dosage of horseradish peroxidase (HRP) and pH value on the conversion of phenol were investigated. The reaction performed very effectively in this novel system when the addition of HRP was only 0.2 mg. In all cases, the weight-average molecular weight calculated by GPC-SLS was in a range from 12000 Da to 30000 Da. The phenol polymer prepared in the present research possessed good thermal stability shown by TG analysis.
2014, 32(7): 914-922
doi: 10.1007/s10118-014-1466-1
Abstract:
In order to improve the flexibility of poly(propylene carbonate) (PPC), poly(1,2-propylene succinate) (PPSu) was used to plasticize PPC in a batch mixer. The effects of PPSu on the miscibility, thermal stability, mechanical and rheological properties of the blends were investigated. PPC was partially miscible with PPSu. It was demonstrated that PPSu decreased the glass transition temperature and melt viscosity of PPC, as shown in the DSC and rheological curves. With the increase in PPSu content, the PPC/PPSu blends showed decreased tensile strength, however, the elongation at break was increased to 1100% for the 70/30 PPC/PPSu blend. The introduction of PPSu provided an efficient and novel plasticization method to extend the application area of PPC.
In order to improve the flexibility of poly(propylene carbonate) (PPC), poly(1,2-propylene succinate) (PPSu) was used to plasticize PPC in a batch mixer. The effects of PPSu on the miscibility, thermal stability, mechanical and rheological properties of the blends were investigated. PPC was partially miscible with PPSu. It was demonstrated that PPSu decreased the glass transition temperature and melt viscosity of PPC, as shown in the DSC and rheological curves. With the increase in PPSu content, the PPC/PPSu blends showed decreased tensile strength, however, the elongation at break was increased to 1100% for the 70/30 PPC/PPSu blend. The introduction of PPSu provided an efficient and novel plasticization method to extend the application area of PPC.
2014, 32(7): 923-930
doi: 10.1007/s10118-014-1482-1
Abstract:
The effect of reverse pressure.on rheological behavior has been studied. The apparatus is a capillary rheometer with counter pressure chamber being held at a high reverse pressure by means of a cock. The results show that with the increase in temperature, the shear viscosity of hydrophilic PET is reduced. It is different that the effect of temperature on shear viscosity is varied under the condition of all shear rates or all pressures, and the effect is more prominent at 50 MPa or at 216 s-1. At the same time, the pressure coefficients decrease with increasing the shear rate and the temperature and tend to reach a constant value nearly at the temperature of 290 ℃.
The effect of reverse pressure.on rheological behavior has been studied. The apparatus is a capillary rheometer with counter pressure chamber being held at a high reverse pressure by means of a cock. The results show that with the increase in temperature, the shear viscosity of hydrophilic PET is reduced. It is different that the effect of temperature on shear viscosity is varied under the condition of all shear rates or all pressures, and the effect is more prominent at 50 MPa or at 216 s-1. At the same time, the pressure coefficients decrease with increasing the shear rate and the temperature and tend to reach a constant value nearly at the temperature of 290 ℃.
2014, 32(7): 931-940
doi: 10.1007/s10118-014-1468-z
Abstract:
A novel phenylacetylene derivative containing urea groups was synthesized and polymerized with a Rh catalyst to give the corresponding polymer, poly(1) with moderate number-average molecular weights. The poly(1) was soluble in toluene, CHCl3, CH2Cl2, THF, DMF, and DMSO, but insoluble in hexane, diethyl ether and MeOH. The specific rotation and circular dichroism (CD) spectroscopic studies revealed that poly(1) took predominantly one-handed helical structures. The presence of intramolecular hydrogen bonding was confirmed by liquid-state IR spectroscopy. The helicity of poly(1) could be tuned by temperature and anion. The helical conformation of the polymer was stable against Br- but susceptible to F-.
A novel phenylacetylene derivative containing urea groups was synthesized and polymerized with a Rh catalyst to give the corresponding polymer, poly(1) with moderate number-average molecular weights. The poly(1) was soluble in toluene, CHCl3, CH2Cl2, THF, DMF, and DMSO, but insoluble in hexane, diethyl ether and MeOH. The specific rotation and circular dichroism (CD) spectroscopic studies revealed that poly(1) took predominantly one-handed helical structures. The presence of intramolecular hydrogen bonding was confirmed by liquid-state IR spectroscopy. The helicity of poly(1) could be tuned by temperature and anion. The helical conformation of the polymer was stable against Br- but susceptible to F-.
2014, 32(7): 941-952
doi: 10.1007/s10118-014-1460-7
Abstract:
A series of sulfonated polyimide copolymers as novel proton exchange materials were synthesized by the polycondensation of 1,4,5,8-naphthalene-tetracarboxylic dianhydride (NTDA), sulfonated diamine based on pyridine group and diamine containing N-phenyl-1,2,4-triazole moiety. Flexible, transparent and tough membranes with high thermal stability and good mechanical properties were obtained. They exhibited good stability in boiling water and Fenton's reagent at 80 ℃. More interestingly, a nonlinear relationship between proton conductivities of the resulting membranes and the degree of sulfonation (DS) was observed. The membrane with 50% DS exhibited the maximum proton conductivity, which was due to the combinational contributions of sulfonic acid and N-pheny-1,2,4-triazole groups. Thus, the N-phenyl-1,2,4-triazole moiety in this study not only can depress water absorption but also increase proton conductivity, especially at low DS.
A series of sulfonated polyimide copolymers as novel proton exchange materials were synthesized by the polycondensation of 1,4,5,8-naphthalene-tetracarboxylic dianhydride (NTDA), sulfonated diamine based on pyridine group and diamine containing N-phenyl-1,2,4-triazole moiety. Flexible, transparent and tough membranes with high thermal stability and good mechanical properties were obtained. They exhibited good stability in boiling water and Fenton's reagent at 80 ℃. More interestingly, a nonlinear relationship between proton conductivities of the resulting membranes and the degree of sulfonation (DS) was observed. The membrane with 50% DS exhibited the maximum proton conductivity, which was due to the combinational contributions of sulfonic acid and N-pheny-1,2,4-triazole groups. Thus, the N-phenyl-1,2,4-triazole moiety in this study not only can depress water absorption but also increase proton conductivity, especially at low DS.
2014, 32(7): 953-960
doi: 10.1007/s10118-014-1463-4
Abstract:
Poly(butylene succinate) (PBS) with different molecular weight was synthesized from 1, 4-butanediol and succinic acid by direct melt condensation. The synthesized PBS was identified by 1H-NMR and FTIR spectrometry. The molecular weight was calculated from the intrinsic viscosity, and its value was between 20000 and 70000. The crystallization behavior and crystal morphology as function of molecular weight were investigated by DSC and PLM, respectively. The mechanical properties and hydrolytic degradation behaviors related with change of molecular weight were also studied in this work. The results demonstrated that the properties of PBS were determined by both molecular weight and crystallization properties (crystallinity as well as crystal morphology). Our work is important for the design and preparation of PBS with proper molecular weight for its practical application.
Poly(butylene succinate) (PBS) with different molecular weight was synthesized from 1, 4-butanediol and succinic acid by direct melt condensation. The synthesized PBS was identified by 1H-NMR and FTIR spectrometry. The molecular weight was calculated from the intrinsic viscosity, and its value was between 20000 and 70000. The crystallization behavior and crystal morphology as function of molecular weight were investigated by DSC and PLM, respectively. The mechanical properties and hydrolytic degradation behaviors related with change of molecular weight were also studied in this work. The results demonstrated that the properties of PBS were determined by both molecular weight and crystallization properties (crystallinity as well as crystal morphology). Our work is important for the design and preparation of PBS with proper molecular weight for its practical application.
2014, 32(7): 961-968
doi: 10.1007/s10118-014-1471-4
Abstract:
Certain amount of primary amine (NH2) groups of hyperbranched polyethylenimine (HPEI) was first protected by Boc groups. Subsequently, the residual reactive amine groups were reacted with isobutyric anhydride to introduce isobutyramide (IBAm) groups to HPEI. Finally, Boc groups were deprotected to result in HPEI-IBAm-NH2 with 18% of primary amine terminals on the periphery and 80% of IBAm terminal groups (abbreviated as HPEI-IBAm0.80-NH2). 1H-NMR characterization proved the successful preparation of the product in each step. Compared with its spatial isomer HPEI-IBAm0.80 without primary amine groups, 1H-NMR spectra verified that more IBAm groups were located in the interior of HPEI-IBAm0.80-NH2. The further modification of HPEI-IBAm0.80-NH2 and HPEI-IBAm0.80 with p-nitrobenzaldehyde demonstrated that HPEI-IBAm0.80-NH2 was more reactive than HPEI-IBAm0.80 due to its possession of primary amines. Turbidimetry measurements showed that HPEI-IBAm0.80-NH2 was thermoresponsive in water. In the pH range of 9.5-10 its cloud point temperature (Tcp) was constant, and it increased obviously upon decreasing the pH below 9.5. The thermoresponsive HPEI-IBAm0.8 exhibited the similar trend, but the pH threshold to achieve the constant Tcp was around 8.5. Moreover, HPEI-IBAm0.8-NH2 showed higher Tcp and broader phase transition than HPEI-IBAm0.8. The mechanism leading to the different thermoresponsive properties between HPEI-IBAm0.8-NH2 and its spatial isomer HPEI-IBAm0.8 was discussed.
Certain amount of primary amine (NH2) groups of hyperbranched polyethylenimine (HPEI) was first protected by Boc groups. Subsequently, the residual reactive amine groups were reacted with isobutyric anhydride to introduce isobutyramide (IBAm) groups to HPEI. Finally, Boc groups were deprotected to result in HPEI-IBAm-NH2 with 18% of primary amine terminals on the periphery and 80% of IBAm terminal groups (abbreviated as HPEI-IBAm0.80-NH2). 1H-NMR characterization proved the successful preparation of the product in each step. Compared with its spatial isomer HPEI-IBAm0.80 without primary amine groups, 1H-NMR spectra verified that more IBAm groups were located in the interior of HPEI-IBAm0.80-NH2. The further modification of HPEI-IBAm0.80-NH2 and HPEI-IBAm0.80 with p-nitrobenzaldehyde demonstrated that HPEI-IBAm0.80-NH2 was more reactive than HPEI-IBAm0.80 due to its possession of primary amines. Turbidimetry measurements showed that HPEI-IBAm0.80-NH2 was thermoresponsive in water. In the pH range of 9.5-10 its cloud point temperature (Tcp) was constant, and it increased obviously upon decreasing the pH below 9.5. The thermoresponsive HPEI-IBAm0.8 exhibited the similar trend, but the pH threshold to achieve the constant Tcp was around 8.5. Moreover, HPEI-IBAm0.8-NH2 showed higher Tcp and broader phase transition than HPEI-IBAm0.8. The mechanism leading to the different thermoresponsive properties between HPEI-IBAm0.8-NH2 and its spatial isomer HPEI-IBAm0.8 was discussed.
