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2012 Volume 30 Issue 2
2012, 30(2): 143-151
doi: 10.1007/s10118-012-1106-6
Abstract:
The main aim of this research is to investigate the effect of salt concentration on the dielectric properties (AC (AC), permittivity (), dielectric loss (), and dielectric relaxation process) and melting behavior of polyethylene oxide (PEO)/CdCl2 complexes. The dielectric study was carried out over a frequency range 10-335 kHz and a temperature range 25-45℃. The AC conductivity, permittivity and dielectric loss of the PEO/CdCl2 complexes increase with increasing salt concentration and temperature. Also, it was found that the addition of CdCl2 salt to PEO host reduced the melting temperature of PEO host. Dielectric results reveal that the relaxation process of these complexes is due to viscoelastic relaxation or non-Debye relaxation at room temperature. Additionally, it was found that relaxation behavior remained viscoelastic at different temperatures and salt concentrations.
The main aim of this research is to investigate the effect of salt concentration on the dielectric properties (AC (AC), permittivity (), dielectric loss (), and dielectric relaxation process) and melting behavior of polyethylene oxide (PEO)/CdCl2 complexes. The dielectric study was carried out over a frequency range 10-335 kHz and a temperature range 25-45℃. The AC conductivity, permittivity and dielectric loss of the PEO/CdCl2 complexes increase with increasing salt concentration and temperature. Also, it was found that the addition of CdCl2 salt to PEO host reduced the melting temperature of PEO host. Dielectric results reveal that the relaxation process of these complexes is due to viscoelastic relaxation or non-Debye relaxation at room temperature. Additionally, it was found that relaxation behavior remained viscoelastic at different temperatures and salt concentrations.
2012, 30(2): 152-163
doi: 10.1007/s10118-012-1107-5
Abstract:
2012, 30(2): 164-172
doi: 10.1007/s10118-012-1108-4
Abstract:
Combining self-consistent-field theory and density-functional theory, we systematically study the deformation of copolymer micelles induced by the presence of amphiphilic dimer particles. Due to the amphiphilic nature, dimer particles tend to accumulate onto the interface of the copolymer micelle. With increasing concentration of the symmetric dimer particles, which are made of two identical spherical particles, the micelle deforms from the initial sphere to ellipse, dumbbell, and finally separates into two micelles. Furthermore, asymmetric dimer particles, composed by two particles with different sizes, are considered to investigate the influence of geometry of dimer particles on the deformation of the micelle. It is found that the micelle inclines to deform into dumbbell due to the additional curvature originating in the gathering of asymmetric dimer particles onto the interface of the micelle. The present study on the deformation of micelles is useful to understand the possible shape variation in the course of cell division/fusion
Combining self-consistent-field theory and density-functional theory, we systematically study the deformation of copolymer micelles induced by the presence of amphiphilic dimer particles. Due to the amphiphilic nature, dimer particles tend to accumulate onto the interface of the copolymer micelle. With increasing concentration of the symmetric dimer particles, which are made of two identical spherical particles, the micelle deforms from the initial sphere to ellipse, dumbbell, and finally separates into two micelles. Furthermore, asymmetric dimer particles, composed by two particles with different sizes, are considered to investigate the influence of geometry of dimer particles on the deformation of the micelle. It is found that the micelle inclines to deform into dumbbell due to the additional curvature originating in the gathering of asymmetric dimer particles onto the interface of the micelle. The present study on the deformation of micelles is useful to understand the possible shape variation in the course of cell division/fusion
2012, 30(2): 173-180
doi: 10.1007/s10118-012-1109-3
Abstract:
Supercritical carbon dioxide (scCO2) was used as a reaction medium in synthesizing amphiphilic graft copolymers composed of poly(styrene-co-maleic anhydride) (SMA) backbones and methoxyl poly(ethylene glycol) (MPEG) side chains via esteri?cation. The synthesized copolymers were characterized by Fourier transform infrared spectroscopy (FTIR), gel permeation chromatography (GPC), 1H-NMR, thermo-gravimetric analysis (TGA) and differential scanning calorimetric analysis (DSC). The gelation phenomenon was suppressed effectively by tuning reaction conditions. The influences of scCO2 temperature and pressure on the conversion of anhydride were investigated. It was found that the highest conversion ratio occurred at 80℃ under a constant pressure of 14 MPa or 26 MPa. With the increase of scCO2 pressure, the conversion ratio increased first, and then leveled off. The conversion ratio of anhydride could be controlled by regulating the reaction conditions. It was also revealed that using low molecular weight MPEG brought a high conversion ratio of anhydride.
Supercritical carbon dioxide (scCO2) was used as a reaction medium in synthesizing amphiphilic graft copolymers composed of poly(styrene-co-maleic anhydride) (SMA) backbones and methoxyl poly(ethylene glycol) (MPEG) side chains via esteri?cation. The synthesized copolymers were characterized by Fourier transform infrared spectroscopy (FTIR), gel permeation chromatography (GPC), 1H-NMR, thermo-gravimetric analysis (TGA) and differential scanning calorimetric analysis (DSC). The gelation phenomenon was suppressed effectively by tuning reaction conditions. The influences of scCO2 temperature and pressure on the conversion of anhydride were investigated. It was found that the highest conversion ratio occurred at 80℃ under a constant pressure of 14 MPa or 26 MPa. With the increase of scCO2 pressure, the conversion ratio increased first, and then leveled off. The conversion ratio of anhydride could be controlled by regulating the reaction conditions. It was also revealed that using low molecular weight MPEG brought a high conversion ratio of anhydride.
2012, 30(2): 181-189
doi: 10.1007/s10118-012-1112-8
Abstract:
A preliminary study of using maleic anhydride copolymer for protein binding has been carried out. The polymeric films were prepared by compression of the purified resin and annealing the film to induce efficient back formation of the anhydride groups. The properties of the film surface were analyzed by attenuated total reflection Fourier transforms infrared spectroscopy and water contact angle measurements. The protein content was determined by Bradford assay. To obtain optimum conditions, immersion time for protein binding was examined. Results revealed that proteins can be successfully immobilized onto the film surface via covalent linkage. The efficiency of the covalent binding of the extractable protein to maleic anhydride-polyethylene film was estimated at 69.87 g/cm2, although the film had low anhydride content (3%) on the surface.
A preliminary study of using maleic anhydride copolymer for protein binding has been carried out. The polymeric films were prepared by compression of the purified resin and annealing the film to induce efficient back formation of the anhydride groups. The properties of the film surface were analyzed by attenuated total reflection Fourier transforms infrared spectroscopy and water contact angle measurements. The protein content was determined by Bradford assay. To obtain optimum conditions, immersion time for protein binding was examined. Results revealed that proteins can be successfully immobilized onto the film surface via covalent linkage. The efficiency of the covalent binding of the extractable protein to maleic anhydride-polyethylene film was estimated at 69.87 g/cm2, although the film had low anhydride content (3%) on the surface.
2012, 30(2): 190-198
doi: 10.1007/s10118-012-1111-9
Abstract:
To explore construction of novel mimicking biomembrane on biomaterials surfaces, a new polymerizable phosphatidylcholine containing a long monoalkyl chain ended with acryl group (AASOPC) was designed and synthesized, which was easily derived from the terminal amino group of 9-(2-amino-ethylcarbamoyl)-nonyl-1-phosphatidyl-choline (ASOPC) reacting with acryloyl chloride. The obtained AASOPC was grafted on poly(ethylene terephthalate) (PET) via surface-initiated atom-transfer radical polymerization (SI-ATRP) to form mimicking biomembrane. These modified surface structures of PET were investigated using water contact angle (WAC), X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). The results indicated that the new mimicking phosphatidylcholine biomembrane could be prepared on inert polymer surfaces by using the acryloyl phosphatidylcholine (AASOPC) via surface-initiated atom transfer radical polymerization (SI-ATRP).
To explore construction of novel mimicking biomembrane on biomaterials surfaces, a new polymerizable phosphatidylcholine containing a long monoalkyl chain ended with acryl group (AASOPC) was designed and synthesized, which was easily derived from the terminal amino group of 9-(2-amino-ethylcarbamoyl)-nonyl-1-phosphatidyl-choline (ASOPC) reacting with acryloyl chloride. The obtained AASOPC was grafted on poly(ethylene terephthalate) (PET) via surface-initiated atom-transfer radical polymerization (SI-ATRP) to form mimicking biomembrane. These modified surface structures of PET were investigated using water contact angle (WAC), X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). The results indicated that the new mimicking phosphatidylcholine biomembrane could be prepared on inert polymer surfaces by using the acryloyl phosphatidylcholine (AASOPC) via surface-initiated atom transfer radical polymerization (SI-ATRP).
MICROSTRUCTURE EVOLUTION OF ISOTACTIC POLYPROPYLENE DURING ANNEALING: EFFECT OF POLY(ETHYLENE OXIDE)
2012, 30(2): 199-208
doi: 10.1007/s10118-012-1121-7
Abstract:
The microstructure evolution of isotactic polypropylene (iPP) during annealing is reported. A few amount of poly(ethylene oxide) (PEO) which exhibits much lower melt temperature compared with iPP was introduced into iPP in this work. The crystalline structure of iPP was detected using differential scanning calorimetry (DSC) and wide-angle X-ray diffraction (WAXD), and the relaxation of iPP was characterized using dynamic mechanical analysis (DMA). The variation of PEO morphology was investigated by scanning electron microscopy (SEM). The results show that the crystallization, including the primary crystallization and second crystallization during annealing, as well as the relaxation of iPP matrix is promoted with the presence of PEO.
The microstructure evolution of isotactic polypropylene (iPP) during annealing is reported. A few amount of poly(ethylene oxide) (PEO) which exhibits much lower melt temperature compared with iPP was introduced into iPP in this work. The crystalline structure of iPP was detected using differential scanning calorimetry (DSC) and wide-angle X-ray diffraction (WAXD), and the relaxation of iPP was characterized using dynamic mechanical analysis (DMA). The variation of PEO morphology was investigated by scanning electron microscopy (SEM). The results show that the crystallization, including the primary crystallization and second crystallization during annealing, as well as the relaxation of iPP matrix is promoted with the presence of PEO.
2012, 30(2): 209-216
doi: 10.1007/s10118-012-1110-x
Abstract:
Liquid crystalline (LC) polymers with a shish-kebab-type moiety on their cross-conjugated (p-phenylene)s-poly(p-phenylenevinylene)s main chains were synthesized through Gilch polymerization in order to develop a kind of polymers available for linearly polarized white-light-emitting from single chain. In this system, the 2,5-bis(4-alkoxyphenyl)benzene as the kebabs connects with poly(p-phenylenevinylene) (PPV) main chain backbone using its molecular gravity center and the PPV as the shish or skewer (the shish-kebab). The polymers possess desirable properties such as excellent solubility and liquid crystalline properties. To drop the kebabs of the 2,5-bis(4-alkoxyphenyl)benzene into the orientation microgroove of aligned polyimide film, not only the shish of polymer main chain can be aligned by the virtue of orientation of kebabs but also the uniform cross-conjugated structure between the kebabs and shish can be broken. Then, the alignment of the polymer main chain showed yellow light emission and was also accompanied by orientation of the LC side chains showing blue light emission, this gave rise to a notable linearly polarized white fluorescence.
Liquid crystalline (LC) polymers with a shish-kebab-type moiety on their cross-conjugated (p-phenylene)s-poly(p-phenylenevinylene)s main chains were synthesized through Gilch polymerization in order to develop a kind of polymers available for linearly polarized white-light-emitting from single chain. In this system, the 2,5-bis(4-alkoxyphenyl)benzene as the kebabs connects with poly(p-phenylenevinylene) (PPV) main chain backbone using its molecular gravity center and the PPV as the shish or skewer (the shish-kebab). The polymers possess desirable properties such as excellent solubility and liquid crystalline properties. To drop the kebabs of the 2,5-bis(4-alkoxyphenyl)benzene into the orientation microgroove of aligned polyimide film, not only the shish of polymer main chain can be aligned by the virtue of orientation of kebabs but also the uniform cross-conjugated structure between the kebabs and shish can be broken. Then, the alignment of the polymer main chain showed yellow light emission and was also accompanied by orientation of the LC side chains showing blue light emission, this gave rise to a notable linearly polarized white fluorescence.
2012, 30(2): 217-226
doi: 10.1007/s10118-012-1114-6
Abstract:
The interactions of non-ionic amphiphilic diblock copolymer poly(oxyethylene/oxybutylene) (E39B18) with anionic surfactant sodium dodecyl sulphate (SDS) and cationic surfactant hexadecyltrimethylammonium bromide (CTAB) were studied by using various techniques such as surface tension, conductivity, steady-state fluorescence and dynamic light scattering. Surface tension measurements were used to determine the critical micelle concentration (CMC) and thereby the free energy of micellization (Gmic), free energy of adsorption (Gads), surface excess concentration () and minimum area per molecule (A). Conductivity measurements were used to determine the critical micelle concentration (CMC), critical aggregation concentration (CAC), polymer saturation point (PSP), degree of ionization () and counter ion binding (). Dynamic light scattering experiments were performed to check the changes in physiochemical properties of the block copolymer micelles taken place due to the interactions of diblock copolymers with ionic surfactants. The ratio of the first and third vibronic peaks (em1/em3) indicated the polarity of the pyrene micro environment and was used for the detection of micelle as well as polymer-surfactant interactions. Aggregation number (N), number of binding sites (n) and free energy of binding (Gb) for pure surfactants as well as for polymer-surfactant mixed micellar systems were determined by the fluorescence quenching method.
The interactions of non-ionic amphiphilic diblock copolymer poly(oxyethylene/oxybutylene) (E39B18) with anionic surfactant sodium dodecyl sulphate (SDS) and cationic surfactant hexadecyltrimethylammonium bromide (CTAB) were studied by using various techniques such as surface tension, conductivity, steady-state fluorescence and dynamic light scattering. Surface tension measurements were used to determine the critical micelle concentration (CMC) and thereby the free energy of micellization (Gmic), free energy of adsorption (Gads), surface excess concentration () and minimum area per molecule (A). Conductivity measurements were used to determine the critical micelle concentration (CMC), critical aggregation concentration (CAC), polymer saturation point (PSP), degree of ionization () and counter ion binding (). Dynamic light scattering experiments were performed to check the changes in physiochemical properties of the block copolymer micelles taken place due to the interactions of diblock copolymers with ionic surfactants. The ratio of the first and third vibronic peaks (em1/em3) indicated the polarity of the pyrene micro environment and was used for the detection of micelle as well as polymer-surfactant interactions. Aggregation number (N), number of binding sites (n) and free energy of binding (Gb) for pure surfactants as well as for polymer-surfactant mixed micellar systems were determined by the fluorescence quenching method.
2012, 30(2): 227-234
doi: 10.1007/s10118-012-1116-4
Abstract:
Ultraviolet (UV)-induced graft copolymerization of allyl acetate (AA) monomer onto poly(ethylene terephthalate) (PET) films and the subsequent sulfonation on the monomer units in the grafting chain using chlorosulfonic acid (ClSO3H) were carried out to prepare proton exchange membranes (PEMs) for fuel cells. A maximum grafting value of 12.8% was found for 35 vol% allyl acetate after 3 h radiation time. Optimum concentration of ClSO3H was selected for the sulfonation reaction to be 0.05 mol/L based on the degree of sulfonation and the tensile strength studies of the membrane. The degree of sulfonation increased as the sulfonation reaction temperature and sulfonation time were increasing. The radiation grafting and the sulfonation have been confirmed by titrimetric and gravimetric analyses as well as FTIR spectroscopy. The maximum ion exchange capacity (IEC) of 0.04125 mmol g-1 was found at 12.1% degree of sulfonation and the maximum proton conductivity was found to be 0.035 S cm-1 at 30℃ and a relative humidity of 60%. The various physical and chemical properties of the PEMs such as water uptake, mechanical strength, thermal durability and oxidative stability were also studied. To investigate the suitability of the prepared membrane for fuel cell applications, its properties were compared with those of Nafion 117.
Ultraviolet (UV)-induced graft copolymerization of allyl acetate (AA) monomer onto poly(ethylene terephthalate) (PET) films and the subsequent sulfonation on the monomer units in the grafting chain using chlorosulfonic acid (ClSO3H) were carried out to prepare proton exchange membranes (PEMs) for fuel cells. A maximum grafting value of 12.8% was found for 35 vol% allyl acetate after 3 h radiation time. Optimum concentration of ClSO3H was selected for the sulfonation reaction to be 0.05 mol/L based on the degree of sulfonation and the tensile strength studies of the membrane. The degree of sulfonation increased as the sulfonation reaction temperature and sulfonation time were increasing. The radiation grafting and the sulfonation have been confirmed by titrimetric and gravimetric analyses as well as FTIR spectroscopy. The maximum ion exchange capacity (IEC) of 0.04125 mmol g-1 was found at 12.1% degree of sulfonation and the maximum proton conductivity was found to be 0.035 S cm-1 at 30℃ and a relative humidity of 60%. The various physical and chemical properties of the PEMs such as water uptake, mechanical strength, thermal durability and oxidative stability were also studied. To investigate the suitability of the prepared membrane for fuel cell applications, its properties were compared with those of Nafion 117.
2012, 30(2): 235-241
doi: 10.1007/s10118-012-1118-2
Abstract:
The present work aimed to study the interaction between plasma proteins and PVP-modified surfaces under more complex protein conditions. In the competitive adsorption of fibrinogen (Fg) and human serum albumin (HSA), the modified surfaces showed preferential adsorption of HSA. In 100% plasma, the amount of Fg adsorbed onto PVP-modified surfaces was as low as 10 ng/cm2, suggesting the excellent protein resistance properties of the modified surfaces. In addition, immunoblots of proteins eluted from the modified surfaces after plasma contact confirmed that PVP-modified surfaces can repel most plasma proteins, especially proteins that play important roles in the process of blood coagulation.
The present work aimed to study the interaction between plasma proteins and PVP-modified surfaces under more complex protein conditions. In the competitive adsorption of fibrinogen (Fg) and human serum albumin (HSA), the modified surfaces showed preferential adsorption of HSA. In 100% plasma, the amount of Fg adsorbed onto PVP-modified surfaces was as low as 10 ng/cm2, suggesting the excellent protein resistance properties of the modified surfaces. In addition, immunoblots of proteins eluted from the modified surfaces after plasma contact confirmed that PVP-modified surfaces can repel most plasma proteins, especially proteins that play important roles in the process of blood coagulation.
2012, 30(2): 242-249
doi: 10.1007/s10118-012-1119-1
Abstract:
We evaluated the biocompatibility of a dimethylpolysiloxane-coated micro-device which had been designed for monitoring real-time bladder volume in previous studies. The extract assay with dimethylpolysiloxane which had been used for coating the micro-device to measure the bladder volume was performed as an in vitro cytotoxicity test. For in vivo biocompatibility testing, the inflammatory responses around the implantation site of the micro-device in subcutaneous tissue of rat were assessed by light microscope with HE stain and fluorescence microscope with ED1 stain and von Willebrand factor stain. The averages of cell viability in dimethylpolysiloxane group were 84.6% and 82.3% at 24 h and 72 h incubation, respectively. The qualitative evaluations with light and fluorescence microscope revealed that the inflammatory changes peaked during 2 weeks but almost disappeared at 4 weeks after implantation of devices. The quantitative evaluations for granulation layer formation and neovascularization showed that the thickness of the layer in dimethylpolysiloxane group peaked during 2 weeks but it came to be stabilized at 4 weeks as thin as at 2 weeks in control group, and the frequency of neovascularization was higher in dimethylpolysiloxane group than in control group but it was not increased with time. The dimethylpolysiloxane-coated micro-device is thought be a reliable bio-medical device.
We evaluated the biocompatibility of a dimethylpolysiloxane-coated micro-device which had been designed for monitoring real-time bladder volume in previous studies. The extract assay with dimethylpolysiloxane which had been used for coating the micro-device to measure the bladder volume was performed as an in vitro cytotoxicity test. For in vivo biocompatibility testing, the inflammatory responses around the implantation site of the micro-device in subcutaneous tissue of rat were assessed by light microscope with HE stain and fluorescence microscope with ED1 stain and von Willebrand factor stain. The averages of cell viability in dimethylpolysiloxane group were 84.6% and 82.3% at 24 h and 72 h incubation, respectively. The qualitative evaluations with light and fluorescence microscope revealed that the inflammatory changes peaked during 2 weeks but almost disappeared at 4 weeks after implantation of devices. The quantitative evaluations for granulation layer formation and neovascularization showed that the thickness of the layer in dimethylpolysiloxane group peaked during 2 weeks but it came to be stabilized at 4 weeks as thin as at 2 weeks in control group, and the frequency of neovascularization was higher in dimethylpolysiloxane group than in control group but it was not increased with time. The dimethylpolysiloxane-coated micro-device is thought be a reliable bio-medical device.
2012, 30(2): 250-257
doi: 10.1007/s10118-012-1115-5
Abstract:
The novel benzoxazine monomer containing phosphorus has been synthesized based on multifunctional amine route from bis(4-aminophenyl)phenylphosphate, p-cresol and formaldehyde. Subsequently, the benzoxazine monomer was thermo-cured into polybenzoxazine containing phosphorus. The chemical structures were identified by nuclear magnetic resonance (NMR), Fourier transform infrared spectroscopy (FT-IR). The curing reaction was monitored by differential scanning calorimetry (DSC) and FT-IR. The thermal and flame-retardant properties of obtained polybenzoxazine were evaluated by dynamic mechanical thermal analysis (DMA), thermal gravimetric analysis (TGA) and oxygen index meter, respectively. The results show that the novel polybenzoxazine has high limiting oxygen index (38.1) and glass transition temperature (232℃).
The novel benzoxazine monomer containing phosphorus has been synthesized based on multifunctional amine route from bis(4-aminophenyl)phenylphosphate, p-cresol and formaldehyde. Subsequently, the benzoxazine monomer was thermo-cured into polybenzoxazine containing phosphorus. The chemical structures were identified by nuclear magnetic resonance (NMR), Fourier transform infrared spectroscopy (FT-IR). The curing reaction was monitored by differential scanning calorimetry (DSC) and FT-IR. The thermal and flame-retardant properties of obtained polybenzoxazine were evaluated by dynamic mechanical thermal analysis (DMA), thermal gravimetric analysis (TGA) and oxygen index meter, respectively. The results show that the novel polybenzoxazine has high limiting oxygen index (38.1) and glass transition temperature (232℃).
MORPHOLOGY STUDY OF A SERIES OF AZOBENZENE-CONTAINING SIDE-ON LIQUID CRYSTALLINE TRIBLOCK COPOLYMERS
2012, 30(2): 258-268
doi: 10.1007/s10118-012-1117-3
Abstract:
A series of azobenzene containing side-on liquid crystalline ABA triblock copolymers were investigated. This triblock series possesses the same central liquid crystal block B and various lengths of the amorphous block A. Transmission electron microscopy (TEM), small angle X-rays and neutron scattering (SAXS and SANS) were used to study their morphologies. After annealing the samples over weeks at a temperature within the nematic temperature range of block B, different morphologies (disordered, lamellar, perforated layer and hexagonal cylinder) were observed by TEM. The alignment behavior of these azo triblock copolymers in the magnetic field for artificial muscle application, as well as the phase period and the order-disorder transition (ODT) were studied in situ by SANS.
A series of azobenzene containing side-on liquid crystalline ABA triblock copolymers were investigated. This triblock series possesses the same central liquid crystal block B and various lengths of the amorphous block A. Transmission electron microscopy (TEM), small angle X-rays and neutron scattering (SAXS and SANS) were used to study their morphologies. After annealing the samples over weeks at a temperature within the nematic temperature range of block B, different morphologies (disordered, lamellar, perforated layer and hexagonal cylinder) were observed by TEM. The alignment behavior of these azo triblock copolymers in the magnetic field for artificial muscle application, as well as the phase period and the order-disorder transition (ODT) were studied in situ by SANS.
2012, 30(2): 269-277
doi: 10.1007/s10118-012-1122-6
Abstract:
The effect of PBS on the morphological features of PVDF has been investigated by optical and atomic force microscopies under various conditions. It was found that neat PVDF forms large form spherulites with extraordinarily weak birefringence at 170℃. Adding 30% PBS makes PVDF exhibit intrigued flower-like spherulitic morphology. The growth mechanism was explained by the decrease of the supercooling and the materials dissipation. Increasing the PBS content to 70% favors the formation of ring banded spherulites. Temperature dependent experiments verify the phase transition occurs from the junction sites of the and crystals, while starts from the centers of spherulites in the blends. Ring banded structures could be observed in neat PVDF, 70/30 blend and 30/70 blend when crystallized at 155℃, without crystals. The band period of PVDF spherulites increases with crystallization temperature as well as the amount of PBS content. At 140℃, spherulites in neat PVDF lose their ring banded feature, while coarse spherulites consisting of evident lamellar bundles could be found in 30/70 blend.
The effect of PBS on the morphological features of PVDF has been investigated by optical and atomic force microscopies under various conditions. It was found that neat PVDF forms large form spherulites with extraordinarily weak birefringence at 170℃. Adding 30% PBS makes PVDF exhibit intrigued flower-like spherulitic morphology. The growth mechanism was explained by the decrease of the supercooling and the materials dissipation. Increasing the PBS content to 70% favors the formation of ring banded spherulites. Temperature dependent experiments verify the phase transition occurs from the junction sites of the and crystals, while starts from the centers of spherulites in the blends. Ring banded structures could be observed in neat PVDF, 70/30 blend and 30/70 blend when crystallized at 155℃, without crystals. The band period of PVDF spherulites increases with crystallization temperature as well as the amount of PBS content. At 140℃, spherulites in neat PVDF lose their ring banded feature, while coarse spherulites consisting of evident lamellar bundles could be found in 30/70 blend.
2012, 30(2): 278-286
doi: 10.1007/s10118-012-1113-7
Abstract:
Cationic latexes were prepared through emulsion copolymerization of styrene (St) and butyl acrylate (BA) with a cationic surfactant, cetyl trimethyl ammonium bromide (CTAB). Latex properties, including particle size, size distribution, potential, surface tension and monomer conversion, were determined for latexes prepared with different CTAB amounts. Evolution of these properties during emulsion polymerization was followed in order to understand the mechanism of the particles formation. Results showed that both particle size and potential were function of polymerization time and latex solids. Parallel emulsion polymerizations with cationic, anionic charged initiator and charge-free initiators were also carried out, the latex properties were determined at different polymerization time. All these results were attentively interpreted based on the mechanisms of emulsion polymerization, surfactant adsorption and latex particle stabilization.
Cationic latexes were prepared through emulsion copolymerization of styrene (St) and butyl acrylate (BA) with a cationic surfactant, cetyl trimethyl ammonium bromide (CTAB). Latex properties, including particle size, size distribution, potential, surface tension and monomer conversion, were determined for latexes prepared with different CTAB amounts. Evolution of these properties during emulsion polymerization was followed in order to understand the mechanism of the particles formation. Results showed that both particle size and potential were function of polymerization time and latex solids. Parallel emulsion polymerizations with cationic, anionic charged initiator and charge-free initiators were also carried out, the latex properties were determined at different polymerization time. All these results were attentively interpreted based on the mechanisms of emulsion polymerization, surfactant adsorption and latex particle stabilization.
2012, 30(2): 287-296
doi: 10.1007/s10118-012-1120-8
Abstract:
A one-step process to introduce both the aromatic and aliphatic primary amino groups with high chemoselectivity was developed. Triplet state acetone abstracts the hydrogen atoms from both the C-H bond of the polymeric film substrate and the O-H bond of phenol which is the building block and the amino group carrier. As a result, two kinds of free radicals, confined carbon-centered chain radicals of the polymer substrate and mobile oxygen-centered phenoxy radicals, were generated. Then the C-O bonds were formed by the coupling reaction between these two kinds of free radicals. p-Tyramine and p-aminophenol were used as amino carriers. The successful introduction of amino groups onto LDPE, BOPP and PET film substrates was demonstrated by measurements of water contract angle (CA), ultraviolet spectra (UV), X-ray photoelectron spectroscopy (XPS) and fluorescent microscopy. The processing factors, such as the UV-light intensity and irradiation time, concentrations of p-tyramine and p-aminophenol, and the ratio of acetone/water were investigated. The optimized process parameters are as follows: UV light intensity 9500 W/cm2; irradiation time 18 min for BOPP and LDPE, 22 min for PET; the ratio of acetone/water = 1; and concentration of p-tyramine and p-aminophenol 15% for BOPP and LDPE, 1% for PET. Based on the UV absorbance, the amino groups on the polymeric substrates were estimated to be in the range of 6.31016-9.510-6mmol/mm2.
A one-step process to introduce both the aromatic and aliphatic primary amino groups with high chemoselectivity was developed. Triplet state acetone abstracts the hydrogen atoms from both the C-H bond of the polymeric film substrate and the O-H bond of phenol which is the building block and the amino group carrier. As a result, two kinds of free radicals, confined carbon-centered chain radicals of the polymer substrate and mobile oxygen-centered phenoxy radicals, were generated. Then the C-O bonds were formed by the coupling reaction between these two kinds of free radicals. p-Tyramine and p-aminophenol were used as amino carriers. The successful introduction of amino groups onto LDPE, BOPP and PET film substrates was demonstrated by measurements of water contract angle (CA), ultraviolet spectra (UV), X-ray photoelectron spectroscopy (XPS) and fluorescent microscopy. The processing factors, such as the UV-light intensity and irradiation time, concentrations of p-tyramine and p-aminophenol, and the ratio of acetone/water were investigated. The optimized process parameters are as follows: UV light intensity 9500 W/cm2; irradiation time 18 min for BOPP and LDPE, 22 min for PET; the ratio of acetone/water = 1; and concentration of p-tyramine and p-aminophenol 15% for BOPP and LDPE, 1% for PET. Based on the UV absorbance, the amino groups on the polymeric substrates were estimated to be in the range of 6.31016-9.510-6mmol/mm2.
2012, 30(2): 297-307
doi: 10.1007/s10118-012-1126-2
Abstract:
A novel encapsulated flame retardant containing phosphorus-nitrogen (MSMM-Al-P) was prepared by encapsulating with polyamide 66 (PA66-MSMM-Al-P) for the flame retardation of polyamide 6 (PA6). The structure and thermal properties of PA66-MSMM-Al-P were characterized by Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy and thermogravimetric analysis. The flammability of PA6 containing flame retardants (MSMM-Al-P and PA66-MSMM-Al-P) was investigated by the limiting oxygen index test, vertical burning test and cone calorimeter. The flame retardancy and cone calorimetric analyses suggested a synergistic effect between PA66 and MSMM-Al-P in the flame-retardant PA6. Thermal stability of the flame-retardant PA6 was also investigated.
A novel encapsulated flame retardant containing phosphorus-nitrogen (MSMM-Al-P) was prepared by encapsulating with polyamide 66 (PA66-MSMM-Al-P) for the flame retardation of polyamide 6 (PA6). The structure and thermal properties of PA66-MSMM-Al-P were characterized by Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy and thermogravimetric analysis. The flammability of PA6 containing flame retardants (MSMM-Al-P and PA66-MSMM-Al-P) was investigated by the limiting oxygen index test, vertical burning test and cone calorimeter. The flame retardancy and cone calorimetric analyses suggested a synergistic effect between PA66 and MSMM-Al-P in the flame-retardant PA6. Thermal stability of the flame-retardant PA6 was also investigated.
2012, 30(2): 308-315
doi: 10.1007/s10118-012-1127-1
Abstract:
Fluorene-based polymers containing perfluorooctyl moieties were designed and synthesized. The high electronegativity and FH-C interactions are present in the fluorinated polymers, which slightly induce blue-shift of UV-Vis absorption in film. The fluoropolymer films prepared from fluorinated solvents show lager contact angles than those prepared in non-fluorinated solvents.
Fluorene-based polymers containing perfluorooctyl moieties were designed and synthesized. The high electronegativity and FH-C interactions are present in the fluorinated polymers, which slightly induce blue-shift of UV-Vis absorption in film. The fluoropolymer films prepared from fluorinated solvents show lager contact angles than those prepared in non-fluorinated solvents.
2012, 30(2): 316-327
doi: 10.1007/s10118-012-1125-3
Abstract:
A series of acrylate processing aid (ACR)-based ionomers with different lanthanide (La(Ⅲ)) ion and acid contents were synthesized, and the interaction between ionomer and zinc stearate (ZnSt2) was investigated immediately after thermally annealing the ionomer/ZnSt2 (3/1 in weight) mixtures at 180℃. The results revealed that the ion groups in ionomer have a strong interaction with ZnSt2. The annealed mixtures contained hot alcohol extractable and unextractable ZnSt2. The melting of ZnSt2 and the thermal behavior of the ionomer in the annealed mixtures were seriously influenced by the contents of La(Ⅲ) and acid in the ionomers. The ionomer containing 0.25 mmol/g acid and 0.37 mmol/g La(Ⅲ) has a detectable cluster phase. Annealing its ZnSt2 mixture could break down the cluster phase and lower glass transition temperature of the ionomer matrix. However, washing away the extractable ZnSt2 led to the reappearance of the cluster transition temperature and return of the glass transition temperature of matrix to the original position.
A series of acrylate processing aid (ACR)-based ionomers with different lanthanide (La(Ⅲ)) ion and acid contents were synthesized, and the interaction between ionomer and zinc stearate (ZnSt2) was investigated immediately after thermally annealing the ionomer/ZnSt2 (3/1 in weight) mixtures at 180℃. The results revealed that the ion groups in ionomer have a strong interaction with ZnSt2. The annealed mixtures contained hot alcohol extractable and unextractable ZnSt2. The melting of ZnSt2 and the thermal behavior of the ionomer in the annealed mixtures were seriously influenced by the contents of La(Ⅲ) and acid in the ionomers. The ionomer containing 0.25 mmol/g acid and 0.37 mmol/g La(Ⅲ) has a detectable cluster phase. Annealing its ZnSt2 mixture could break down the cluster phase and lower glass transition temperature of the ionomer matrix. However, washing away the extractable ZnSt2 led to the reappearance of the cluster transition temperature and return of the glass transition temperature of matrix to the original position.
2012, 30(2): 328-336
doi: 10.1007/s10118-012-1128-0
Abstract:
A cholesterol-based organogelator bearing an anthraquinone imide (AQI) group was synthesized and characterized. It self-assembled into chiral gels in acetonitrile at low concentrations, which displayed a combination of electrochromic and chiroptical properties. Upon electrochemical reduction at-700 mV, the gel exhibited new absorption bands at around 820 nm corresponding to *-* (SOMOLUMO) transitions of the radical anion of AQI and strong negative Cotton effects in the same spectral region. With further reduction at-1000 mV, a new CD band with a negative Cotton effect in the range from 500 nm to 800 nm appeared concomitant with the variation of absorption spectrum. Thus, with the use of electrochromic AQI chromophore as a switch-responsive unit and the stable gel of compound N-[3-cholest-5-en-3-yl N-(2-aminoethyl) carbamate] anthraquinone-2,3-dicarboxylic imide as a chiral scaffold, a redox-triggered chiroptical switch operating in visible and near-infrared region was realized.
A cholesterol-based organogelator bearing an anthraquinone imide (AQI) group was synthesized and characterized. It self-assembled into chiral gels in acetonitrile at low concentrations, which displayed a combination of electrochromic and chiroptical properties. Upon electrochemical reduction at-700 mV, the gel exhibited new absorption bands at around 820 nm corresponding to *-* (SOMOLUMO) transitions of the radical anion of AQI and strong negative Cotton effects in the same spectral region. With further reduction at-1000 mV, a new CD band with a negative Cotton effect in the range from 500 nm to 800 nm appeared concomitant with the variation of absorption spectrum. Thus, with the use of electrochromic AQI chromophore as a switch-responsive unit and the stable gel of compound N-[3-cholest-5-en-3-yl N-(2-aminoethyl) carbamate] anthraquinone-2,3-dicarboxylic imide as a chiral scaffold, a redox-triggered chiroptical switch operating in visible and near-infrared region was realized.
