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2014 Volume 32 Issue 10
2014, 32(10): 1271-1275
doi: 10.1007/s10118-014-1523-9
Abstract:
Herein, we show that rod-like tobacco mosaic virus (TMV) can self-assemble into 3D bundled structures in aqueous solution using azobenzene modified Pluronics F127 block copolymers (Azo-F127) to induce depletion. The structures are characterized by both transmission electron microscopy and dynamic light scattering. The self-assembly process can be controlled reversibly by temperature. The formation of Azo-F127 hard spheres during the self-assembly is the main cause of this phenomenon.
Herein, we show that rod-like tobacco mosaic virus (TMV) can self-assemble into 3D bundled structures in aqueous solution using azobenzene modified Pluronics F127 block copolymers (Azo-F127) to induce depletion. The structures are characterized by both transmission electron microscopy and dynamic light scattering. The self-assembly process can be controlled reversibly by temperature. The formation of Azo-F127 hard spheres during the self-assembly is the main cause of this phenomenon.
2014, 32(10): 1276-1285
doi: 10.1007/s10118-014-1521-y
Abstract:
Synergistic effect in network formation of nylon-6 (PA6) nanocomposites containing one dimensional (1D) multi-walled carbon nanotubes (CNTs) and two dimensional (2D) layered double hydroxide (LDH) platelets on improving the mechanical properties has been studied. Mechanical tests show that, with incorporation of 1 wt% LDHs and 0.5 wt% CNTs, the tensile modulus, the yield strength as well as the hardness of the ternary composite are greatly improved by about 230%, 128% and 110% respectively, as compared with neat PA6. This is mainly attributed to the unique, strong interactions between the CNTs and the LDHs as well as the jammed network-like structure thus formed between the nanofillers, as confirmed by the morphological observations. As compared with the binary nanocomposites, a much enhanced solid-like behavior in the terminal region of the rheological curves can clearly be observed for the ternary system, which also indicates the formation of a percolating filler network.
Synergistic effect in network formation of nylon-6 (PA6) nanocomposites containing one dimensional (1D) multi-walled carbon nanotubes (CNTs) and two dimensional (2D) layered double hydroxide (LDH) platelets on improving the mechanical properties has been studied. Mechanical tests show that, with incorporation of 1 wt% LDHs and 0.5 wt% CNTs, the tensile modulus, the yield strength as well as the hardness of the ternary composite are greatly improved by about 230%, 128% and 110% respectively, as compared with neat PA6. This is mainly attributed to the unique, strong interactions between the CNTs and the LDHs as well as the jammed network-like structure thus formed between the nanofillers, as confirmed by the morphological observations. As compared with the binary nanocomposites, a much enhanced solid-like behavior in the terminal region of the rheological curves can clearly be observed for the ternary system, which also indicates the formation of a percolating filler network.
2014, 32(10): 1286-1297
doi: 10.1007/s10118-014-1522-x
Abstract:
Polyurethanes consisting of tri-functional homopolymer of hexamethylene diisocyanate (tri-HDI) and polyethylene glycol (PEG) are synthesized, in which photo-reversible coumarin moieties act as pendant groups. Accordingly, the polyurethanes can be repeatedly self-healed under UV lights at room temperature by taking advantages of the photodimerization and photocleavage habits of coumarin. Molecular weight of the soft segment, PEG, is found to be closely related to the healing performance of the polyurethanes. Lower molecular weight PEG that corresponds to higher initial coumarin concentration in the polymer is critical for obtaining higher healing efficiency in the case of the first healing action. Nevertheless, it does not guarantee high reversibility of the photo-remendability during the repeated healing events. In contrast, the polyurethane with moderate molecular weight PEG has achieved balanced performance. Reaction kinetics is less important for the healing effect.
Polyurethanes consisting of tri-functional homopolymer of hexamethylene diisocyanate (tri-HDI) and polyethylene glycol (PEG) are synthesized, in which photo-reversible coumarin moieties act as pendant groups. Accordingly, the polyurethanes can be repeatedly self-healed under UV lights at room temperature by taking advantages of the photodimerization and photocleavage habits of coumarin. Molecular weight of the soft segment, PEG, is found to be closely related to the healing performance of the polyurethanes. Lower molecular weight PEG that corresponds to higher initial coumarin concentration in the polymer is critical for obtaining higher healing efficiency in the case of the first healing action. Nevertheless, it does not guarantee high reversibility of the photo-remendability during the repeated healing events. In contrast, the polyurethane with moderate molecular weight PEG has achieved balanced performance. Reaction kinetics is less important for the healing effect.
2014, 32(10): 1298-1310
doi: 10.1007/s10118-014-1520-z
Abstract:
We present a coarse-grained molecular dynamics simulation study of phase behavior of amphiphilic monolayers at the liquid crystal (LC)/water interface. The results revealed that LCs at interface can influence the lateral ordering of amphiphiles. Particularly, the amphiphile tails along with perpendicularly penetrated LCs between tails undergo a two-dimension phase transition from liquid-expanded into a liquid-condensed phase as their area density at interface reaches 0.93. While, the liquid-condensed phase of the monolayer never appears at oil/water interface with isotropic shape oil particles. These findings reveal the penetration of anisotropic LC can promote ordered lateral organization of amphiphiles.Moreover, we find the phase transition point is shifted to lower surface coverage of amphiphiles when the LCs have larger affinity to the amphiphile tails.
We present a coarse-grained molecular dynamics simulation study of phase behavior of amphiphilic monolayers at the liquid crystal (LC)/water interface. The results revealed that LCs at interface can influence the lateral ordering of amphiphiles. Particularly, the amphiphile tails along with perpendicularly penetrated LCs between tails undergo a two-dimension phase transition from liquid-expanded into a liquid-condensed phase as their area density at interface reaches 0.93. While, the liquid-condensed phase of the monolayer never appears at oil/water interface with isotropic shape oil particles. These findings reveal the penetration of anisotropic LC can promote ordered lateral organization of amphiphiles.Moreover, we find the phase transition point is shifted to lower surface coverage of amphiphiles when the LCs have larger affinity to the amphiphile tails.
2014, 32(10): 1311-1318
doi: 10.1007/s10118-014-1511-0
Abstract:
Starch/boron nitride (starch/BN) bionanocomposites were prepared with the reinforcement of boron nitride nano powder by solution technique. The dispersion of BN in the starch was achieved by a continuous sonication process. The interaction between starch and boron nitride nanopowder was investigated by Fourier transform infrared (FTIR) spectroscopy. The structural properties of starch/BN bionanocomposites was studied by X-ray diffraction (XRD). The high resolution transmission electron microscopy (HRTEM) was used for the study of dispersion of boron nitride in starch matrix and diffraction patterns were studied by selected area electron diffraction (SAED). Thermal stability of the starch was increased with rising concentrations of boron nitride due to incorporation of rigid nano BN with starch matrix. The substantial reduction in oxygen permeability was obtained by increasing the concentration of BN. The biodegradability of synthesized bionanocomposites was measured by using activated sludge water. Further, it was noticed that, starch/BN bionanocomposites are resistant towards inorganic acids and bases. The tensile strength of starch/BN bionanocomposites was increased whereas; the water resistance property of the materials was decreased with increasing BN loading.
Starch/boron nitride (starch/BN) bionanocomposites were prepared with the reinforcement of boron nitride nano powder by solution technique. The dispersion of BN in the starch was achieved by a continuous sonication process. The interaction between starch and boron nitride nanopowder was investigated by Fourier transform infrared (FTIR) spectroscopy. The structural properties of starch/BN bionanocomposites was studied by X-ray diffraction (XRD). The high resolution transmission electron microscopy (HRTEM) was used for the study of dispersion of boron nitride in starch matrix and diffraction patterns were studied by selected area electron diffraction (SAED). Thermal stability of the starch was increased with rising concentrations of boron nitride due to incorporation of rigid nano BN with starch matrix. The substantial reduction in oxygen permeability was obtained by increasing the concentration of BN. The biodegradability of synthesized bionanocomposites was measured by using activated sludge water. Further, it was noticed that, starch/BN bionanocomposites are resistant towards inorganic acids and bases. The tensile strength of starch/BN bionanocomposites was increased whereas; the water resistance property of the materials was decreased with increasing BN loading.
2014, 32(10): 1319-1328
doi: 10.1007/s10118-014-1513-y
Abstract:
New siloxane and sulfone containing poly(benzimidazole/sulfone/siloxane/amide) (PBSSA) has been prepared for the formation of hybrid membranes (PBSSA/PS-S/SiNPs) with sulfonated polystyrene (PS-S) and 0.1 wt%-2 wt% silica nanoparticles (SiNPs). Field emission scanning electron micrographs showed good dispersion of filler, formation of dense nanoporous honeycomb like structure and uniform ionic pathway in these hybrids. The porous membrane structure was responsible for the fine water retention capability and higher proton conductivity of the new hybrids. Increasing the amount of nanoparticles from 0.1 wt% to 2 wt% increased the tensile stress of acid doped PBSSA/PS-S/SiNPs nanocomposites from 65.7 MPa to 68.5 MPa. A relationship between nanofiller loading and thermal stability of the membranes was also experientially studied, as the glass transition temperature of phosphoric acid doped PBSSA/PS-S/SiNPs nanocomposites increased from 207℃ to 215℃. The membranes also had higher ion exchange capacity (IEC) around 2.01 mmol/g to 3.01 mmol/g. The novel membranes with high IEC value achieved high proton conductivity of 1.10-2.34 S/cm in a wide range of humidity values at 80℃ which was higher than that of perfluorinated Nafion117 membrane (1.1 10-1 S/cm) at 80℃ (94% RH). A H2/O2 fuel cell using the PBSSA/PS-S/SiNP 2 (IEC 3.01 mmol/g) showed better performance than that of Nafion 117 at 40℃ and 30% RH.
New siloxane and sulfone containing poly(benzimidazole/sulfone/siloxane/amide) (PBSSA) has been prepared for the formation of hybrid membranes (PBSSA/PS-S/SiNPs) with sulfonated polystyrene (PS-S) and 0.1 wt%-2 wt% silica nanoparticles (SiNPs). Field emission scanning electron micrographs showed good dispersion of filler, formation of dense nanoporous honeycomb like structure and uniform ionic pathway in these hybrids. The porous membrane structure was responsible for the fine water retention capability and higher proton conductivity of the new hybrids. Increasing the amount of nanoparticles from 0.1 wt% to 2 wt% increased the tensile stress of acid doped PBSSA/PS-S/SiNPs nanocomposites from 65.7 MPa to 68.5 MPa. A relationship between nanofiller loading and thermal stability of the membranes was also experientially studied, as the glass transition temperature of phosphoric acid doped PBSSA/PS-S/SiNPs nanocomposites increased from 207℃ to 215℃. The membranes also had higher ion exchange capacity (IEC) around 2.01 mmol/g to 3.01 mmol/g. The novel membranes with high IEC value achieved high proton conductivity of 1.10-2.34 S/cm in a wide range of humidity values at 80℃ which was higher than that of perfluorinated Nafion117 membrane (1.1 10-1 S/cm) at 80℃ (94% RH). A H2/O2 fuel cell using the PBSSA/PS-S/SiNP 2 (IEC 3.01 mmol/g) showed better performance than that of Nafion 117 at 40℃ and 30% RH.
2014, 32(10): 1329-1337
doi: 10.1007/s10118-014-1510-1
Abstract:
Multifunctional nanocarriers with multilayer core-shell architecture were prepared by coating superparamagnetic Fe3O4 nanoparticles with diblock copolymer folate-poly(ethylene glycol)-b-poly(glycerol monomethacrylate) (FA-PEG-b-PGMA), and triblock copolymer methoxy poly(ethylene glycol)-b-poly(2-(dimethylamino) ethyl methacrylate)-b-poly(glycerol monomethacrylate) (MPEG-b-PDMA-b-PGMA). The PGMA segment was attached to the surfaces of Fe3O4 nanoparticles, and the outer PEG shell imparted biocompatibility. In addition, folate was conjugated onto the surfaces of the nanocarriers. Cisplatin was then loaded into the nanocarrier by coordination between the Pt atom in cisplatin and the amine groups in the inner shell of the multilayer architecture. The loaded cisplatin showed pH-responsive release: slower release at pH 7.4 (i.e. mimicking the blood environment) and faster release at more acidic pH (i.e. mimicking endosome/lysosome conditions). All of the cisplatin-loaded nanoparticles showed concentration-dependent cytotoxicity in HeLa cells. However, the folate-conjugated cisplatin-loaded carriers exhibited higher cytotoxicity in HeLa cells than non-folate conjugated cisplatin-loaded carriers.
Multifunctional nanocarriers with multilayer core-shell architecture were prepared by coating superparamagnetic Fe3O4 nanoparticles with diblock copolymer folate-poly(ethylene glycol)-b-poly(glycerol monomethacrylate) (FA-PEG-b-PGMA), and triblock copolymer methoxy poly(ethylene glycol)-b-poly(2-(dimethylamino) ethyl methacrylate)-b-poly(glycerol monomethacrylate) (MPEG-b-PDMA-b-PGMA). The PGMA segment was attached to the surfaces of Fe3O4 nanoparticles, and the outer PEG shell imparted biocompatibility. In addition, folate was conjugated onto the surfaces of the nanocarriers. Cisplatin was then loaded into the nanocarrier by coordination between the Pt atom in cisplatin and the amine groups in the inner shell of the multilayer architecture. The loaded cisplatin showed pH-responsive release: slower release at pH 7.4 (i.e. mimicking the blood environment) and faster release at more acidic pH (i.e. mimicking endosome/lysosome conditions). All of the cisplatin-loaded nanoparticles showed concentration-dependent cytotoxicity in HeLa cells. However, the folate-conjugated cisplatin-loaded carriers exhibited higher cytotoxicity in HeLa cells than non-folate conjugated cisplatin-loaded carriers.
2014, 32(10): 1338-1347
doi: 10.1007/s10118-014-1509-7
Abstract:
Acetamide (C2), propionamide (C3), butyramide (C4), isobutyramide (i-C4), isovaleramide (i-C5) and trimethylacetamide (t-C5) groups each were introduced to the terminals of hyperbranched polyethylenimine (HPEI) through the amidation reaction between HPEI and the corresponding anhydride. Moreover, HPEIs terminated with two kinds of amides were also prepared. The first amide was fixed to be i-C4 with 52% degree of amidation (DA), and the second amide varied from C2, C3, C4, i-C5 to t-C5. All the polymers were characterized by 1H-NMR. Turbidimetry measurements were performed for these polymers in water at different temperatures. With respect to the polymers bearing only one kind of amide group, except C2, all the other amide groups could render thermoresponsive properties to HPEI. The specific ordering of these amide groups to reduce the cloud point temperature (Tcp) was as follows: i-C5 t-C5 C4 i-C4 C3. Moreover, the more branched i-C4 and t-C5 were better groups than their less branched isomers C4 and i-C5 in the Tcp range of 12-51℃ to render the sharper phase transition to the thermoresponsive polymers. As for the polymers bearing two kinds of amide groups, the further introduction of C2, C3, C4, i-C5 or t-C5 could effectively endow HPEI bearing 52% of i-C4 with thermoresponsive properties. The specific ordering of these second amide groups to reduce the Tcp was as follows:i-C5 C4 i-C4 C3 C2. C4, i-C5 and t-C5 were all effective second amide groups to prepare the thermoresponsive polymers with sharper phase transition.
Acetamide (C2), propionamide (C3), butyramide (C4), isobutyramide (i-C4), isovaleramide (i-C5) and trimethylacetamide (t-C5) groups each were introduced to the terminals of hyperbranched polyethylenimine (HPEI) through the amidation reaction between HPEI and the corresponding anhydride. Moreover, HPEIs terminated with two kinds of amides were also prepared. The first amide was fixed to be i-C4 with 52% degree of amidation (DA), and the second amide varied from C2, C3, C4, i-C5 to t-C5. All the polymers were characterized by 1H-NMR. Turbidimetry measurements were performed for these polymers in water at different temperatures. With respect to the polymers bearing only one kind of amide group, except C2, all the other amide groups could render thermoresponsive properties to HPEI. The specific ordering of these amide groups to reduce the cloud point temperature (Tcp) was as follows: i-C5 t-C5 C4 i-C4 C3. Moreover, the more branched i-C4 and t-C5 were better groups than their less branched isomers C4 and i-C5 in the Tcp range of 12-51℃ to render the sharper phase transition to the thermoresponsive polymers. As for the polymers bearing two kinds of amide groups, the further introduction of C2, C3, C4, i-C5 or t-C5 could effectively endow HPEI bearing 52% of i-C4 with thermoresponsive properties. The specific ordering of these second amide groups to reduce the Tcp was as follows:i-C5 C4 i-C4 C3 C2. C4, i-C5 and t-C5 were all effective second amide groups to prepare the thermoresponsive polymers with sharper phase transition.
2014, 32(10): 1348-1356
doi: 10.1007/s10118-014-1516-8
Abstract:
Cassava starch-based superabsorbent polymer was successfully synthesized using a new technology that based on modification of a Haake twin-roll mixer as reactor. The cassava starch was first gelatinized then modified by grafting under external shear stress in the reactor. The torque and temperature curves as a function of time can reflect the variations in the reactor and also offer some information about the copolymerization reaction. The advantages of this system include starch modification can be carried out (1) with high starch concentration, (2) under controlled time and (3) smaller amount of sample (60 g) required. The technology provides useful guides for reactive extrusion. The starch grafted composites were characterized by Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR) and thermal gravimetric analysis (TGA). The TGA was also used for determining the percentage of grafting ratio. The results show that the cassava starch has been successfully grafted with acrylamide then crosslinked by N,N'-methylene-bisacrylamide using this reactor. The ultimate water absorbent capacity of the cassava-based superabsorbent polymer impacted by various pH values illustrated that the acid and basic solutions inhibit the ability of imbibing water. Additionally, gel properties of the cassava-based superabsorbent polymer were investigated. It can be concluded that the structure of cassava gel is stable, while the three dimensional network of cassava-based superabsorbent polymer is rigid but its structure could not resist external force effectively and everlastingly since G' was decreased with increasing amplitude.
Cassava starch-based superabsorbent polymer was successfully synthesized using a new technology that based on modification of a Haake twin-roll mixer as reactor. The cassava starch was first gelatinized then modified by grafting under external shear stress in the reactor. The torque and temperature curves as a function of time can reflect the variations in the reactor and also offer some information about the copolymerization reaction. The advantages of this system include starch modification can be carried out (1) with high starch concentration, (2) under controlled time and (3) smaller amount of sample (60 g) required. The technology provides useful guides for reactive extrusion. The starch grafted composites were characterized by Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR) and thermal gravimetric analysis (TGA). The TGA was also used for determining the percentage of grafting ratio. The results show that the cassava starch has been successfully grafted with acrylamide then crosslinked by N,N'-methylene-bisacrylamide using this reactor. The ultimate water absorbent capacity of the cassava-based superabsorbent polymer impacted by various pH values illustrated that the acid and basic solutions inhibit the ability of imbibing water. Additionally, gel properties of the cassava-based superabsorbent polymer were investigated. It can be concluded that the structure of cassava gel is stable, while the three dimensional network of cassava-based superabsorbent polymer is rigid but its structure could not resist external force effectively and everlastingly since G' was decreased with increasing amplitude.
2014, 32(10): 1357-1362
doi: 10.1007/s10118-014-1525-7
Abstract:
Polypropylene samples with fullerene C60, fullerenol C60(OH)24, 1010, C60/168, C60-OH/168 and 1010/168 as antioxidants were prepared by extrusions. MFR, YI, TGA and OIT of all the samples were tested. According to the results of MFR, during the melt extrusion, fullerene showed excellent stability effect on PP. The antioxidative ability of fullerene was comparable to the traditional antioxidant 1010. The antioxidative ability of fullerenol was not significant in the first extrusion and it accelerated the degradation of PP in the second and the third extrusions. TGA and OIT tests showed that the stability effects of fullerene and fullerenol were slightly lower than antioxidant 1010. In the first time, antioxidant 168 was reported to show great synergistic effects with fullerene and fullerenol as antioxidants, which sussested a simple way to enhance the antioxidative abilities of fullerene and fullerenol.
Polypropylene samples with fullerene C60, fullerenol C60(OH)24, 1010, C60/168, C60-OH/168 and 1010/168 as antioxidants were prepared by extrusions. MFR, YI, TGA and OIT of all the samples were tested. According to the results of MFR, during the melt extrusion, fullerene showed excellent stability effect on PP. The antioxidative ability of fullerene was comparable to the traditional antioxidant 1010. The antioxidative ability of fullerenol was not significant in the first extrusion and it accelerated the degradation of PP in the second and the third extrusions. TGA and OIT tests showed that the stability effects of fullerene and fullerenol were slightly lower than antioxidant 1010. In the first time, antioxidant 168 was reported to show great synergistic effects with fullerene and fullerenol as antioxidants, which sussested a simple way to enhance the antioxidative abilities of fullerene and fullerenol.
2014, 32(10): 1363-1372
doi: 10.1007/s10118-014-1526-6
Abstract:
In order to improve the optical and mechanical performances of waterborne polyurethane (WPU), nanocrystalline cellulose (NCC)/WPU composites were synthesized in this study. NCC (prepared by acid hydrolysis of cotton fiber) was modified by (3-aminopropyl)triethoxysilane (APTES) to enhance its compatibility with WPU, and the surface-modified NCC was characterized by grafting ratio, crystallinity and contact angle (CA). NCC/WPU composites were examined by scanning electron microscopy (SEM), X-ray powder diffraction (XRD) and thermogravimetric analysis (TG). The anti-yellowing property, specular gloss, pencil hardness, and abrasion resistance of NCC/WPU composites were investigated by the methods of Chinese National Standards GB/T 23999-2009, GB/T 9754-2007, GB/T 6739-2006 and GB/T 1768-2006, respectively. The results showed that the grafting ratio of NCC modified by 6% APTES was 36.01% and the crystallinity of modified NCC was decreased with the enhancement of APTES. CA of the modified NCC was decreased by 28.8% and the nanoparticles were homogeneously dispersed in the WPU matrix. The XRD patterns of the NCC/WPU composites were relatively steady, while the thermal stability of the composites was enhanced by 6.7% with 1.0 wt% modified NCC. Modified NCC affected the specular gloss of NCC/WPU composites more obviously than the anti-yellowing property. The pencil hardness of NCC/WPU composites was increased from 2H to 4H by addition of NCC and the abrasion resistance of the composites was enhanced significantly. In general, NCC/WPU composites showed significant improvements in the optical and mechanical performances.
In order to improve the optical and mechanical performances of waterborne polyurethane (WPU), nanocrystalline cellulose (NCC)/WPU composites were synthesized in this study. NCC (prepared by acid hydrolysis of cotton fiber) was modified by (3-aminopropyl)triethoxysilane (APTES) to enhance its compatibility with WPU, and the surface-modified NCC was characterized by grafting ratio, crystallinity and contact angle (CA). NCC/WPU composites were examined by scanning electron microscopy (SEM), X-ray powder diffraction (XRD) and thermogravimetric analysis (TG). The anti-yellowing property, specular gloss, pencil hardness, and abrasion resistance of NCC/WPU composites were investigated by the methods of Chinese National Standards GB/T 23999-2009, GB/T 9754-2007, GB/T 6739-2006 and GB/T 1768-2006, respectively. The results showed that the grafting ratio of NCC modified by 6% APTES was 36.01% and the crystallinity of modified NCC was decreased with the enhancement of APTES. CA of the modified NCC was decreased by 28.8% and the nanoparticles were homogeneously dispersed in the WPU matrix. The XRD patterns of the NCC/WPU composites were relatively steady, while the thermal stability of the composites was enhanced by 6.7% with 1.0 wt% modified NCC. Modified NCC affected the specular gloss of NCC/WPU composites more obviously than the anti-yellowing property. The pencil hardness of NCC/WPU composites was increased from 2H to 4H by addition of NCC and the abrasion resistance of the composites was enhanced significantly. In general, NCC/WPU composites showed significant improvements in the optical and mechanical performances.
2014, 32(10): 1373-1380
doi: 10.1007/s10118-014-1515-9
Abstract:
Monomer of 7-methacryloyloxy-4-methylcoumarin (MAOMC) was synthesized and characterized by FTIR, 1H-NMR and 13C-NMR spectroscopy. Copolymers of MAOMC with butoxyethylmethacrylate (BOEMA) at different feed compositions were prepared by free radical solution polymerization at (70 1)℃ in ethylmethylketone (EMK) using benzyl peroxide (BPO) as an initiator. The copolymers were characterized by FTIR and 1H-NMR spectroscopy. Thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) of the copolymers showed moderate thermal stability and higher Tg values. Gel permeation chromatography (GPC) was used to find out the molecular weights of the different copolymers. Antibacterial activities of the copolymers were also investigated against the selected pathogenic bacteria's. The antibacterial activity of the copolymer increases as the MAOMC content increases in the copolymer. This shows that coumarin moiety plays a very important role in the antibacterial activity.
Monomer of 7-methacryloyloxy-4-methylcoumarin (MAOMC) was synthesized and characterized by FTIR, 1H-NMR and 13C-NMR spectroscopy. Copolymers of MAOMC with butoxyethylmethacrylate (BOEMA) at different feed compositions were prepared by free radical solution polymerization at (70 1)℃ in ethylmethylketone (EMK) using benzyl peroxide (BPO) as an initiator. The copolymers were characterized by FTIR and 1H-NMR spectroscopy. Thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) of the copolymers showed moderate thermal stability and higher Tg values. Gel permeation chromatography (GPC) was used to find out the molecular weights of the different copolymers. Antibacterial activities of the copolymers were also investigated against the selected pathogenic bacteria's. The antibacterial activity of the copolymer increases as the MAOMC content increases in the copolymer. This shows that coumarin moiety plays a very important role in the antibacterial activity.
2014, 32(10): 1381-1389
doi: 10.1007/s10118-014-1524-8
Abstract:
Loach skin mucin was isolated from loach skin mucus and found to be similar to mammalian mucins in many aspects, i.e., low amino acid residue content, high molecular weight, presence of hydrophobic blocks and gel-forming characteristics in water. However, loach skin mucin can form a weak gel in water at a much lower concentration (3 mg/mL) than mammalian mucins, indicating its good hydrophilicity. Loach skin mucin can also form a stable adsorption layer on gold surface in aqueous environment, owing to the existence of hydrophobic blocks within mucin. The nature of high hydrophilicity and interfacial behavior give loach skin mucin potential as excellent material for use in solid-water interfaces for antifouling and lubrication, and should be crucial to the versatile functions of loach skin mucus.
Loach skin mucin was isolated from loach skin mucus and found to be similar to mammalian mucins in many aspects, i.e., low amino acid residue content, high molecular weight, presence of hydrophobic blocks and gel-forming characteristics in water. However, loach skin mucin can form a weak gel in water at a much lower concentration (3 mg/mL) than mammalian mucins, indicating its good hydrophilicity. Loach skin mucin can also form a stable adsorption layer on gold surface in aqueous environment, owing to the existence of hydrophobic blocks within mucin. The nature of high hydrophilicity and interfacial behavior give loach skin mucin potential as excellent material for use in solid-water interfaces for antifouling and lubrication, and should be crucial to the versatile functions of loach skin mucus.
2014, 32(10): 1390-1399
doi: 10.1007/s10118-014-1514-x
Abstract:
The focus of this work is to control the structure of electrosprayed polymer microspheres and then study the effect of different structures on the microspheres' adsorption properties. Scanning electron microscopy (SEM) coupled with image analysis software was employed to evaluate the size distributions and the structure of microspheres. According to the observation and analysis results, two types of polyethersulfone (PES) porous microspheres (perfect sphere-shaped and collapsed) were prepared via electrospraying technology by adjusting the solvent and polymer molecular weight. The porous PES microspheres can remove bisphenol A (BPA) from its aqueous solution effectively. Compared with collapsed microspheres, the rough microspheres had much higher specific surface area and better mobility in the BPA aqueous solution, so it showed a better adsorption capacity than that of collapsed microspheres. The solvent evaporation rate and the occurrence rate of phase separation significantly affect the structure and morphology of microspheres.
The focus of this work is to control the structure of electrosprayed polymer microspheres and then study the effect of different structures on the microspheres' adsorption properties. Scanning electron microscopy (SEM) coupled with image analysis software was employed to evaluate the size distributions and the structure of microspheres. According to the observation and analysis results, two types of polyethersulfone (PES) porous microspheres (perfect sphere-shaped and collapsed) were prepared via electrospraying technology by adjusting the solvent and polymer molecular weight. The porous PES microspheres can remove bisphenol A (BPA) from its aqueous solution effectively. Compared with collapsed microspheres, the rough microspheres had much higher specific surface area and better mobility in the BPA aqueous solution, so it showed a better adsorption capacity than that of collapsed microspheres. The solvent evaporation rate and the occurrence rate of phase separation significantly affect the structure and morphology of microspheres.
2014, 32(10): 1400-1412
doi: 10.1007/s10118-014-1498-6
Abstract:
In order to investigate the partition of initiators for quasi-static precipitation polymerization of acrylamide (AAm) and methacrylic acid (MAc) in ethanol, azo-initiators were employed with various functional groups such as -COOCH3 (V-601, dimethyl 2,2-azobis(isobutyrate)), -CN (V-65, 2,2-Azobis(2,4-diemthylvaleronitrile)), -COOH (V-501, 4,4-azobis(4-cyanovaleric acid)) and -NH-(VA-061, 2,2-azobis[2-(2-imidazolin-2-yl)propane]), respectively. Particle size, induction time and kinetics of polymerization were investigated by the scanning electron microscopy (SEM) and gravimetry. It was observed that the polymerization parameters, such as the particle size, induction time and polymerization rate, were considerably affected by the functional groups of initiators. Besides, the monomer concentration also played important roles in the particle formation. By using V-601, the polymerization rate was strongly correlated with the total surface area of particles and the concentration of initiators. However, by using V-501, the polymerization rate was strongly related to W0Ci,0, where W0 is the initial concentration of monomers and Ci,0, the initial concentration of initiators. The results indicated that the different functional groups determined the different partition types of initiators between the minimonomer droplets and the continuous phase due to the molecular interactions of initiator and monomers. V-601 was all partitioned in the continuous phase, but a part of V-65 was partitioned in the minimonomer droplets. Besides the V-501 dissolved in the continuous phase, a part of V-501 was adsorbed on the surface of minimonomer droplets. VA-061 destroyed the stability of minimonomer droplets by the formation of zwitterions with MAA.
In order to investigate the partition of initiators for quasi-static precipitation polymerization of acrylamide (AAm) and methacrylic acid (MAc) in ethanol, azo-initiators were employed with various functional groups such as -COOCH3 (V-601, dimethyl 2,2-azobis(isobutyrate)), -CN (V-65, 2,2-Azobis(2,4-diemthylvaleronitrile)), -COOH (V-501, 4,4-azobis(4-cyanovaleric acid)) and -NH-(VA-061, 2,2-azobis[2-(2-imidazolin-2-yl)propane]), respectively. Particle size, induction time and kinetics of polymerization were investigated by the scanning electron microscopy (SEM) and gravimetry. It was observed that the polymerization parameters, such as the particle size, induction time and polymerization rate, were considerably affected by the functional groups of initiators. Besides, the monomer concentration also played important roles in the particle formation. By using V-601, the polymerization rate was strongly correlated with the total surface area of particles and the concentration of initiators. However, by using V-501, the polymerization rate was strongly related to W0Ci,0, where W0 is the initial concentration of monomers and Ci,0, the initial concentration of initiators. The results indicated that the different functional groups determined the different partition types of initiators between the minimonomer droplets and the continuous phase due to the molecular interactions of initiator and monomers. V-601 was all partitioned in the continuous phase, but a part of V-65 was partitioned in the minimonomer droplets. Besides the V-501 dissolved in the continuous phase, a part of V-501 was adsorbed on the surface of minimonomer droplets. VA-061 destroyed the stability of minimonomer droplets by the formation of zwitterions with MAA.
2014, 32(10): 1413-1418
doi: 10.1007/s10118-014-1517-7
Abstract:
Photosensitizer (photosan)-encapsulated micelles were prepared by self-assembly of Photosan with two amphiphilic polysaccharide derivatives, including the cholesteryl conjugated sodium alginate derivative (CSAD) and the deoxycholic acid group conjugated chitosan derivative (DA-Chit). The results of UV-Vis and fluorescence spectroscopy indicated that the hydrogen bonding strength dominated the micelle formation. Methyl viologen was used as a model quencher of photosan. Using the steady-state fluorescence technology, the quenching constants were determined to be 2.05, 1.88 and 0.30 L/mmol for the free photosan, the photosan-CSAD micelle and the photosan-DA-Chit micelle, respectively. This suggested that photosan was protected from quenching of methyl viologen by the polysaccharide micelles. In addition, the protection effect of the photosan-DA-Chit micelle was significantly stronger than that of the photosan-CSAD micelle. The photosan-DA-Chit micelle is thus anticipated for protection of photoactivity of photosan during the blood circulation process in vivo.
Photosensitizer (photosan)-encapsulated micelles were prepared by self-assembly of Photosan with two amphiphilic polysaccharide derivatives, including the cholesteryl conjugated sodium alginate derivative (CSAD) and the deoxycholic acid group conjugated chitosan derivative (DA-Chit). The results of UV-Vis and fluorescence spectroscopy indicated that the hydrogen bonding strength dominated the micelle formation. Methyl viologen was used as a model quencher of photosan. Using the steady-state fluorescence technology, the quenching constants were determined to be 2.05, 1.88 and 0.30 L/mmol for the free photosan, the photosan-CSAD micelle and the photosan-DA-Chit micelle, respectively. This suggested that photosan was protected from quenching of methyl viologen by the polysaccharide micelles. In addition, the protection effect of the photosan-DA-Chit micelle was significantly stronger than that of the photosan-CSAD micelle. The photosan-DA-Chit micelle is thus anticipated for protection of photoactivity of photosan during the blood circulation process in vivo.
