SYNTHESIS AND CHARACTERIZATION OF A NEW COMB-LIKE POLYMER-BASED ON POLY(VINYL METHYL ETHER-ALT-MALEIC ANHYDRIDE) BACKBONE

A new comblike polymer host for polymer electrolyte was synthesized by reacting monomethyl ether of poly(ethylene glycol) with poly(vinyl methyl ether-alt-maleic anhydride) and endcapping the residual carboxylic acid with methanol. Butanone was selected as a solvent for the esterification in order to obtain a completely soluble product. The synthesis process was traced through by LR. Compared with the model compounds, the presumed structure of this comblike polymer has been proved to be valid by C-13 NMR The comb polymer is a white rubbery solid. It can be dissolved in butanone and THF, and manifests good film forming ability.

EXCIMER FLUORESCENCE STUDY ON THE MISCIBILITY OF POLY(VINYL METHYL-ETHER) AND STYRENE-BUTADIENE STYRENE TRIBLOCK COPOLYMER

The excimer fluorescence of a triblock copolymer, styrene-butadiene-styrene (SBS) containing 48 wt% polystyrene was used to investigate its miscibility with poly(vinyl methyl ether) (PVME). The excimer-to-monomer emission intensity ratio I(M)/I(E) can be used as a sensitive probe to determine the miscibility level in SBS/PVME blends: I(M)/I(E) is a function of PVME concentration, and reaches a maximum when the blend contains 60% PVME. The cloud point curve determined by light scattering shows a pseudo upper critical solution temperature diagram, which can be attributed to the effect of PB segments in SBS. The thermally induced phase separation of SBS/PVME blends can be observed by measuring I(M)/I(E), and the phase dissolution process was followed by measuring I(M)/I(E) at different times.

Properties of poly(sodium 4-styrenesulfonate)-ionic liquid composite film and its application in the determination of trace metals combined with bismuth film electrode

A new kind of bismuth film modified electrode to sensitively detect trace metal ions based on incorporating highly conductive ionic liquids 1-butyl-3-methyl-imidazolium hexafluorophosphate (BMIMPF6) in solid matrices at glassy carbon (GC) was investigated. Poly(sodium 4-styrenesulfonate) (PSS), silica, and Nafion were selected as the solid matrices. The electrochemical properties of the mixed films modified GC were evaluated. The electron transfer rate of Fe(CN)(6)(4-)/Fe(CN)(6)(3-) can be effectively improved at the PSS-BMIMPF6 modified GC.

Thermoplastic Elastomers Based on Compatibilized Poly(butylene terephthalate) Blends: Effect of Functional Groups and Dynamic Curing

Two sets of graft copolymers were prepared by grafting glycidyl methacrylate (GMA) or ally] (3-isocyanate-4-tolyl) carbamate (TAI) onto ethylene/propylene/diene terpolymer (EPDM) in an internal mixer. These graft copolymers were used as the compatibilizer to prepare the thermoplastic elastomers (TPEs) containing 50 wt%, of poly(butylene terephthalate), PBT, 30 wt% of compatibilizer, and 20 wt% of nitrile-butadiene rubber, NBR. The indirect, two-step mixer process was chosen for dynamic curing.

Synthesis and characterization of novel biodegradable poly(carbonate ester)s with photolabile protecting groups

Novel biodegradable poly(carbonate ester)s with photolabile protecting groups were synthesized by ring-opening copolymerization Of L-lactide (LA) with 5-methyl-5-(2-nitro-benzoxycarbonyl)-1,3-dioxan-2-one (MNC) with diethyl zinc (Et2Zn) as catalyst. The poly(L-lactide-co-5-methyl-5-carboxyl-1,3-dioxan-2-one) (P(LA-co-MCC)) was obtained by UV irradiation Of poly(L-lactide acid-co-5-methyl-5-(2-nitro-benzoxycarbonyl)-1,3-dioxan-2-one) (P(LA-co-MNC)) to remove the protective 2-nitrobenzyl group.

Controlled release of urea encapsulated by starch-g-poly(L-lactide)

This paper presented a new approach for preparing a new type of slow-release membrane-encapsulated urea fertilizer with starch-g-PLLA as biodegradable carrier materials. By solution-casting and washing rapidly with water the urea was individually encapsulated within the starch matrix modified by L-lactide through in situ graft-copolymerization.

Novel aliphatic poly(ester-carhonate) with pendant allyl ester groups and its folic acid functionalization

A series of novel poly(ester-carbonate)s bearing pendant allyl ester groups P(LA-co-MAC)s were prepared by ring-opening copolymerization Of L-lactide (LA) and 5-methyl-5-allyloxycarbonyl-1,3-dioxan-2-one (MAC) with diethyl zinc (ZnEt2) as initiator. NMR analysis investigated the microstructure of the copolymer. DSC results indicated that the copolymers displayed a single glass-transition temperature (T-g), which was indicative of a random copolymer, and the Tg decreased with increasing carbonate content in the copolymer.

Aliphatic Poly(ester-carbonate)s Bearing Amino Groups and Its RGD Peptide Grafting

This article deals with (1) synthesis of novel cyclic carbonate monomer (2-oxo [1,3]dioxan-5-yl)carbamic acid benzyl ester (CAB) containing protected amino groups; (2) ring-opening copolymerization of the cyclic monomer with L-lactide (LA) to provide novel degradable poly(ester-carbonate)s with functional groups; (3) removal of the protective benzyloxycarbonyl (Cbz) groups by catalytic hydrogenation to afford the corresponding poly(ester-co-carbonate)s with free amino groups; (4) grafting of oligopeptide Gly-Arg-Gly-Asp-Ser-Tyr (GRGDSY, abbreviated as RGD) onto the copolymer pendant amino groups in the presence of 1,1'-carbonyldiimidazole (CDI).

Thermal and mechanical properties of poly(butylene terephthalate)/epoxy blends

In this study, melt blends of poly(butylene terephthalate) (PBT) with epoxy resin were characterized by dynamic mechanical analysis, differential scanning calorimetry, tensile testing, Fourier transform infrared spectroscopy, and wide-angle X-ray diffraction. The results indicate that the presence of epoxy resin influenced either the mechanical properties of the PBT/epoxy blends or the crystallization of PBT. The epoxy resin was completely miscible with the PBT matrix. This was beneficial to the improvement of the impact performance of the PBT/epoxy blends.

Selective hydrogenation of unsaturated aldehydes in a poly(ethylene glycol)/compressed carbon dioxide biphasic system

Hydrogenation of alpha,beta-unsaturated aldehydes (citral, 3-methyl-2-butenal, cinnamaldehyde) has been studied with tetrakis(triphenylphosphine) ruthenium dihydride (H2Ru(TPP)(4)) catalyst in a poly(ethylene glycol) (PEG)/ compressed carbon dioxide biphasic system. The hydrogenation reaction was slow under PEG/ H-2 biphasic conditions at H-2 4 MPa in the absence of CO2. When the reaction mixture was pressurized by a non-reactant of CO2, however, the reaction was significantly accelerated.

Dispersions of carbon nanotubes in sulfonated poly[bis(benzimidazobenzisoquinolinones)] and their proton-conducting composite membranes

A sulfonated poly[bis(benzimidazobenzisoquinolinones)] (SPBIBI) possessing a conjugated pyridinone ring was shown to be effective for dispersing multiwalled carbon nanotubes (MWCNTs) in DMSO. The dispersions in which the SPBIBI to MWCNTs mass ratio was 4:1 demonstrated the highest MWCNTs concentrations, i.e., 1.5-2.0 mg mL(-1), and were found to be stable for more than six months at room temperature. Through casting of these dispersions, MWCNTs/SPBIBI composite membranes were successfully fabricated on substrates as proton exchange membranes for fuel cell applications and showed no signs of macroscopic aggregation. The properties of composite membranes were investigated, and it was found that the homogeneous dispersion of the MWCNTs in the SPBIBI matrix altered the morphology structures of the composite membranes, which lead to the formation of more regular and smaller cluster-like ion domains.

Blends based on sulfonated poly[bis(benzimidazobenzisoquinolinones)] and poly(vinylidene fluoride) for polymer electrolyte membrane fuel cell

A new blend system consisting of an amorphous sulfonated poly[bis(benzimidazobenzisoquinolinones)] (SPBIBI) and the semi-crystalline poly(vinylidene fluoride) (PVDF) was prepared for proton exchange membranes. The miscibility behavior of a series of blends of SPBIBI with PVDF at various weight ratios was studied by WXRD, DSC and FTIR. The properties of the blend membranes were investigated, and it was found that the introduction of PVDF in the SPBIBI matrix altered the morphological structure of the blend membranes, which led to the formation of improved connectivity channels. For instance, the conductivity of the blend membrane containing 10 wt% PVDF displayed the highest proton conductivity (i.e., 0.086 S cm(-1)) at room temperature, a value almost twofold that of the pristine SPBIBI membranes (i.e., 0.054S cm(-1)) under identical conditions.

The nanocomposite scaffold of poly(lactide-co-glycolide) and hydroxyapatite surface-grafted with L-lactic acid oligomer for bone repair

Nanohydroxyapatite (op-HA) surface-modified with L-lactic acid oligomer (LAc oligomer) was prepared by LAc oligomer grafted onto the hydroxyapatite (HA) surface. The nanocomposite of op-HA/PLGA with different op-HA contents of 5, 10, 20 and 40 wt.% in the composite was fabricated into three-dimensional scaffolds by the melt-molding and particulate leaching methods. PLGA and the nanocomposite of HA/PLGA with 10 wt.% of ungrafted hydroxyapatite were used as the controls. The scaffolds were highly porous with evenly distributed and interconnected pore structures, and the porosity was around 90%. Besides the macropores of 100-300 mu m created by the leaching of NaCl particles, the micropores (1-50 mu m) in the pore walls increased with increasing content of op-HA in the composites of op-HA/PLGA. The op-HA particles could disperse more uniformly than those of pure HA in PLGA matrix. The 20 wt.% op-HA/PLGA sample exhibited the maximum mechanical strength, including bending strength (4.14 MPa) and compressive strength (2.31 MPa). The cell viability and the areas of the attached osteoblasts on the films of 10 wt.% op-HA/PLGA and 20 wt.% op-HA/PLGA were evidently higher than those on the other composites.

Effects of fullerene solubility on the crystallization of poly(3-hexylthiophene) and performance of photovoltaic devices

The substantial crystallization suppression of poly(3-hexylthiophene) (P3HT) in the untreated P3HT:C60 composite film prepared from o-dichlorobenzene (ODCB) solution has been revealed. Besides, the effective conjugation length of P3HT in this composite has been nearly maintained to that in the solution. The different crystallization behaviors of P3HT in its composites with C60 and [6,6]-phenyl C-61 butyric acid methyl ester (PCBM) are mainly attributed to the relative solubility of C60 and PCBM with respect to P3HT in ODCB. The solution to overcome this disadvantage of chain conformation and crystallinity of P3HT in the composite with C60 is thus proposed and finalized by resorting to the addition of low volatile solvent with much higher solubility of C60 than P3HT into the main solvent used, so as P3HT can crystallize before C60 forms crystallites in the solution. The feasibility of this approach has been proven by the improved efficiency of devices based on composites of P3HT and the low cost C60 without resorting to post-treatments.