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A simple and efficient route for one-pot synthesis of high-molecular-weight aliphatic polycarbonates (APCs) by directly melt transesterification of diphenyl carbonate (DPC) with aliphatic diols at equimolar amounts was developed. Zn(OAc) 2 was found to be the best catalyst for this reaction among the screened transition metal acetates. The effects of reaction conditions on M w and yield of the poly(1,4-butylene carbonate) (PBC) were investigated, where the highest M w of 156200 g/mol with yield of 83 % was obtained under suitable reaction conditions. In addition, based on the results of thermogravimetric and differential thermal analysis (TG-DTA), X-ray diffraction (XRD), scanning electron microscope (SEM) and fourier transform infrared spectroscopy (FT-IR), a plausible reaction mechanism over Zn(OAc) 2 was proposed for APCs synthesis.

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Graft copolymerization of corn starch with acrylamide using ceric ammonium sulphate/citric acid initiation system has been studied under nitrogen atmosphere in aqueous medium. The grafting parameters are favored by increasing monomer concentration and reaction time but are affected by higher concentration of initiator and high temperature. The optimum conditions established for grafting were as follows: the concentration of initiator, 0.003 mol/L; the concentration of citric acid, 0.03 mol/L; monomer/starch, 1:1 feed ratio (w/w); reaction time, 3.0 h; and temperature, 35°C. The extent of grafting was examined by Fourier transform infrared spectroscopy, X-ray diffraction, and scanning electron microscopy. Both swelling power and solubility increased with the increase in temperature. Graft copolymerization increased swelling power and reduced solubility. Rapid visco-analyzer pasting profile was studied. Graft copolymerization of corn starch results in high pasting temperature, high peak viscosity, and setback as compared with native starch. Breakdown was retarded at low percentage grafting (6.60%) but increased at high percentage grafting (60.27%). POLYM. COMPOS., 28: 47-56, 2007.

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Aiming at meeting the specific market demands and expanding the downstream application of melamine-formaldehyde (MF) resins, a series of (3-aminopropyl) triethoxysilane (APTES) grafted MF (MF-Si) resins were synthesized via an effective method that minimized the hydrolysis of APTES and overcame the polarity discrepancy of APTES with MF resin matrix. The structure of MF-Si resins was characterized by FTIR spectroscopy, Raman spectroscopy, 1 H nuclear magnetic resonance (NMR), and solid state 13 C NMR. It was found that APTES moieties in MF-Si materials afforded increased hydrophobicity, water resistance, and the thermal stability was not affected. With the increasing amount of APTES, the water contact angle of MF-Si films increased from 70.56 to 105.92 and the surface free energy decreased from 46.8 to 23.5 mN/m. The temperature of maximum weight loss rate (T dmax ) of MF-Si materials decreased slightly from 371.15 to 353.70 C and the ultimate residual weight of MF-Si materials increased from 12.51 to 30.04% at 800 C under N 2 .