MISCIBILITY OF POLY(N-VINYL-2-PYRROLIDONE) WITH POLY(ETHER SULFONE) AND 2 PHENOLPHTHALEIN-BASED POLYMERS

Blends of poly(N-vinyl-2-pyrrolidone) (PVP) with poly(ether sulphone) and two phenolphthalein-based polymers, viz. phenolphthalein poly(ether ether sulphone) and phenolphthalein poly(ether ether ketone) were prepared by casting from a common solvent and studied by differential scanning calorimetry. It was found that all the PVP blends are miscible and show a single, composition-dependent glass transition temperature (T(g)). The T(g)-composition dependence has been analysed by the use of the Gordon-Taylor equation. The values of the k parameter in the Gordon-Taylor equation obtained are all not high for the three pairs, in accordance with the fact that there is no strongly specific interaction between PVP and any of the other polymers.

WATER-SOLUBLE AND AMPHIPHILIC POLYMERS .11. GRAFT-POLYMERIZATION OF ACRYLIC-ACID ON POLY(VINYL ALCOHOL)

The graft polymerization of acrylic acid(AA) on poly(vinyl alcohol) (PVAL) has been investigated by using either potassium persulfate (KPS) or ceric ammonium nitrate(CAN) as an initiator. In the case of KPS initiation, the formation of the graft polymer always lags behind the homopolymer formation. The graft polymer is separated by acetone, and the increase of reaction temperature favors the homopolymer formation at the early stage. In the case of CAN initiation, graft polymers with a high PAA content can hardly be obtained when the polymerization is performed under nitrogen and at < 0.06 mol/L HNO3 concentration. It has been found that incorporation of a small amount of oxygen in a protective nitrogen gas accelerates markedly the graft polymerization, and that the resulting graft polymers can not be separated by acetone precipitation technique in most cases. The Dalian nitrogen(containing 0.7% oxygen) is a good protective gas for CAN-initiated PVAL-AA graft polymerization.

INSITU CONDUCTIVITY ELECTROCHEMISTRY OF CONDUCTIVE POLYMERS - POLY(3-METHYLTHIOPHENE) AND POLYTHIOPHENE

In situ monitoring of conductivity and potential response of conductive polymers during electrochemical process had been described. A renewable carbon fibre array ring-glassy carbon disk electrode was used for this purpose. Poly(3-methylthiophene) and polythiophene were investigated with this method, and some 5 orders in magnitude of conductivity changes were observed during the electrochemical redox process.

MORPHOLOGY AND DYNAMIC MECHANICAL-PROPERTIES OF AB CROSS-LINKED POLYMERS BASED ON POLYURETHANES

Polyoxypropylene glycol (PPG) (or castor oil) and toluene diisocyanate (TDI) were mixed, and the prepolymer polyurethane (PU) (I) was formed. Vinyl-terminated polyurethane (II) was prepared from (I), and hydroxyethyl acrylate, AB crosslinked polymers (ABCPs) were synthesized from (II) and vinyl monomers such as styrene, methyl methacrylate, vinyl acetate, etc. The dynamic mechanical properties and morphology of ABCPs were measured. The ABCPs based on PPG have double glass transition temperatures (T(g)) on the sigma-vs. temperature curves. They display a two-phase morphology with plastic components forming the continous phase and PU-rich domains forming the separated phase on the electron micrographs. Irregular shapes and a highly polydisperse distribution of PU-rich domain sizes were observed. The crosslink density of ABCPs has a notable effect on the morphology and properties. The average diameter of the PU-rich domains depends on the molecular weight of prepolymer PPG. The highly crosslinked structures will produce large numbers of very small domains. ABCPs based on castor oil show a single T(g) relaxation on the dynamic mechanical spectra. The compatibility between the two components is much better in ABCPs based on castor oil than in those based on PPG, because there is a high crosslink density in the former. Comparison of the dynamic mechanical spectra of ABCP and interpenetrating networks (IPN) based on castor oil with similar crosslink density and composition imply that the two components in ABCP are compatible whereas microphase separation occurs in IPN. An improvement in the compatibility is achieved by the crosslinking between the two networks.

WATER-SOLUBLE AND AMPHIPHILIC POLYMERS .6. A STUDY ON THE SURFACE-COMPOSITION OF CAST FILMS OF PST/PMAA AND PEO-PST-PEO BLOCK POLYMERS BY XPS

Thin films of PSt/PMAA and PEO-PSt-PEO block polymers were deposited on a polystyrene substrate by solution adsorption (with or without solvent treatment), and the film surfaces were characterized by means of XPS. Direct solvent - casting of PEO-PSt-PEO from benzene solutions resulted in PSt-rich surfaces, whereas PMAA richer surfaces were obtained for PSt/PMAA films cast from DMF solutions. Moreover, solvent treatment after casting had profound effect on the film surface composition. Treatment with water markedly increased the surface concentration of polar PEO segments. In the case of PSt-PMAA block polymers, the PSt content on the surface increased in the order of water < ethanol < cyclohexane < petroleum ether, the last-named giving films with almost pure PSt surface. It is well worth noticing that the bulk composition had little to do with the surface composition for both PSt/PMAA and PEO-PSt-PEO block polymers within the composition range investigated when subsequent solvent treatment was applied.

WATER-SOLUBLE AND AMPHIPHILIC POLYMERS .7. SYNTHESIS AND CHARACTERIZATION OF A NOVEL COMB-TYPE AMPHIPHILIC POLYMER PAMC16S

A novel comb-like amphiphilic polymer, poly (2-acrylamidohexadecylsulfonic acid) (PAMC16S), was synthesized by free radical polymerization of the corresponding amphiphilic monomer in 1,4-dioxane-water mixed solvents. Depending on the ratio of water/dioxane in the solvent, the reaction proceeded by either precipitation polymerization or micellar polymerization. The molecular weight of the polymer obtained under similar conditions decreased and subsequently increased with the increase of water content in the mixed solvent. The polyion nature of PAMC16S was confirmed by viscosity data of ethanolic solutions. In addition, the polymer was characterized by solubility, IR, TG and wide angle X-ray diffraction methods.

Studies on two coordination polymers [M(mu(4)-pz25dc)](n) (M = Cd or Zn, pz25dc=pyrazine-2,5-dicarboxylato) with three-dimensional pillared-layer three-nodal framework: Synthesis, structural characterization, strong optical non-linearities and optical limiting properties

Two isomorphous new candidates [M(mu(4)-pz25dc)](n) (M = Cd, 1; Zn, 2; pz25dc = pyrazine-2,5-dicarboxylato)for nonlinear optical (NLO) materials have been synthesized hydrothermally and characterized crystallographically as pillared-layer three-nodal frameworks with one four-connected metal nodes and two crystallographically different four-connected ligand nodes. Their optical non-linearities are measured by the Z-Scan technique with an 8 ns pulsed laser at 532 nm. These two coordination polymers both exhibit strong NLO absorptive abilities [alpha(2) = (63 +/- 6) x 10 (12) mW (1) 1, ( 46 +/- 6) x 10 (11) mW (1) 2] and effective self-focusing performance [n(2) = (67 +/- 5) x 10 (18) 1, (13 +/- 3) x 10 (18) m(2) W (1) 2] in 1.02 x 10 (4) 1 and 1.05 x 10 (4) mol dm (3) 2 DMF solution separately. The values of the limiting threshold are also measured from the optical limiting experimental data. The heavy atom effect plays important role in the enhancement of optical non-linearities and optical limiting properties. (C) 2009 Elsevier B. V. All rights reserved.