ABSTRACT:To study the effect of the silica content on the properties of the salt-free and salt-added hybrids based on poly(ethylene oxide) (PEO) and silica, two series of hybrids, PEO-silica and PEO-silica-LiClO 4 (O:Li, 9:1) hybrids were prepared via the in situ acid-catalyzed sol-gel reactions of the precursors [i.e., PEO functionalized with triethoxysilane and tetraethyl orthosilicate (TEOS)]. The morphology of the hybrids was examined by scanning electron microscopy (SEM) of the fracture surfaces of the hybrid. The results indicated that the discontinuity develops with increasing the weight percent of silica in both hybrids. The differential scanning calorimetric (DSC) analysis indicated that effects of silica content on the glass transition temperatures (T g ) of the PEO phase were different in salt-free and salt-added hybrids. The T g of PEO phase increased with increasing weight percent of silica in salt-free hybrids, whereas the curve of T g of PEO phase and silica content had a maximum at 35 wt % of silica content in salt-added hybrids. For both salt-free and salt-added hybrids, peaks of the loss tangent, determined by dynamic mechanical analysis (DMA) were gradually broadened and lowered with increasing weight percent of silica. The storage modulus, EЈ, in the region above T g increases with increasing silica content for both PEO-silica and PEO-silica-LiClO 4 hybrids. In the conductivity and composition curves for PEOsilica-LiClO 4 hybrids, the conductivity shows a maximum value of 3.7 ϫ 10 Ϫ6 S/cm, corresponding to the sample with a 35 wt % of silica.

Energetic thermoplastic polyurethane elastomers (ETPUs) of glycidyl azide polymer (GAP) were synthesized on GAP/poly(caprolactone)(PCL) (100/0, 50/50) as a soft segment and methylenebis(phenylisocyanate) (MDI) extended 1,5-pentanediol as a hard segment by solution polymerization in dimethyl formamide (DMF). Differential scanning calorimetry (DSC) and thermo gravimetric analysis (TGA) were used to examine the thermal decomposition behavior. Kinetic analysis was performed with model fitting and a model-free method to obtain the activation energy as a function of the extent of conversion. ETPU decomposition was divided into two stages with different activation energies. The first main weight loss step corresponds to the elimination of N 2 from the decomposition of -N 3 bonds within azide polymers. The activation energy of the main decomposition of GAP ETPU and GAP/PCL ETPU was approximately 190 kJ/mol. The second weight loss step coincides with the decomposition of the skeleton. The activation energy of those showed an increasing trend.

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This work introduces cationic ring opening polymerization of polyepichlorohydrin (PECH) produced under various reaction conditions (set temperature: −10 to 40°C, [C]/[I] ratio: 0.1–1, monomer feed rate: 1–4 mL/min). In addition, a correlation between the exothermic reaction temperature and the performance of the PECH was obtained by utilizing a reaction temperature monitoring system, GPC, 1H‐NMR, and FTIR. During the polymerization, an induction period which affects the polydispersity was observed below 10°C. At lower temperatures and lower [C]/[I] ratios, a higher induction period was observed. The monomer feed rate did not affect the induction period but it highly affected the polydispersity when the induction period occurred. The total molecular weight of PECH increased with decreasing set temperature even though the amount of low molecular weight cyclic oligomer increased. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 39912.

Poly(N‐substituted urethane)s with an alkyl or ligo(ethylene oxide) monomethyl ether side chain were synthesized by the reaction operating in the following two‐step process: first, by metalation of the starting polymer with potassium tertiary butoxide (t‐BuOK) and then by treatment of the obtained urethane polyanion with tosylate in dimethyl sulfoxide. The thermal properties of poly(ethylene oxide) poly(N‐substituted urethane) (N‐sub PEOPU) were investigated in view of the N‐substitution degree and properties of the substituent. The chemical structures were characterized by Fourier transform infrared, 1H NMR, and 13C NMR spectroscopies. DSC and thermogravimetric analysis (TGA) were used to investigate the thermal properties of N‐sub PEOPUs. As the degree of N‐methylation increased, the glass‐transition temperature (Tg) of the N‐sub PEOPUs linearly decreased from 6 to −29 °C, and the weight‐loss temperature of 5% (T 5%d) from TGA in air increased from 278 to 360 °C. In the fully N‐substituted PEOPUs, the behavior of the thermal decomposition of the PEOPU that was processed in two stages was changed to one‐step decomposition in the temperature range of 360–440 °C. The Tg was shifted to a lower temperature with an increasing length of the substituent in N‐sub PEOPU. Improvement of the thermal stability by N‐substitution was more significant in N‐alkyl PEOPU than in N‐ethoxylate PEOPU. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 4129–4138, 2001