Syndiotactic polystyrene miscible blends

Differential scanning calorimetry (DSC) experiments indicated that atactic polystyrene and polyvinyl methyl ether (PVME) form miscible blends [8,9]. Syndiotactic and isotactic polystyrene when blended with PVME, phase separate at aU temperatures above the glass transition temperature of PVME. Only weak van der Waals interactions between the phenyl rings in polystyrene with the methoxy group of PVME were detected using 2-dimensional nuclear magnetic resonance (NMR) spectroscopy. 

S. Cimmino, E. D. Pace, E. Martuscelli, C. Silvestre, D. M. Rice, and F. E. Karasz, Miscibility of syndiotactic polystyrene/poly(vinyl methyl ether) blends. Polymer, Vol. 34, 214-217, 1993. 

Blends of PPO with PS containing sulfonated and carboxylated groups have been reported in various studies [394-396]. The miscibility of sulfonated PS with PPO, sulfonated PPO with PS and blends of the sulfonated polymers was reported by Hseih and Peilfer [394]. Miscibility was maintained with sulfonation levels up to 2-4mol% for PS with sulfonated PPO and sulfonated PS with PPO. When both polymers were sulfonated, phase separation occurred at higher levels (> 10mol% sulfonation). The miscibility can be influenced by counter ion, as noted in a comparison of a Zn + neutralized sulfonic acid modified PS, which exhibited a larger miscibility window with PPO than the Na neutralized coimterpart [396]. Syndiotactic polystyrene was noted to be miscible over the entire composition range in amorphous blends with PPO, where the Tg versus composition followed the Fox equation predictions [397]. Isotactic polystyrene miscibility with PPO has also been observed, with crystallization and orientation data reported on the blend [398]. 

Poly(cyclohexyl acrylate) was shown to be miscible with PS with ucst behavior [720]. Random copolymers of cyclohexyl acrylate with n-butyl acrylate showed miscibility with PS above 50% cyclohexyl acrylate[721]. Poly(cyclohexyl methacrylate)/isotactic PS blends showed miscibility based on calorimetry and NMR studies [722]. The NMR results showed homogeneous behavior at a scale of 2.5-3.5 nm. Poly(4-trimethylsilyl styrene) miscibility with polyisoprene was observed with a lest behavior (critical temperature = 172 ° C at degree of polymerization of 370) [723]. The interaction parameter, showed the following relationship = 0.027—9.5/T. Isotactic and syndiotactic polystyrene both exhibit crystallinity, whereas atactic polystyrene is amorphous. Atactic PS/isotactic PS blends exhibited crystallization kinetics, which decreased linearly with atactic PS addition indicating miscibility [724]. The TgS of aPS and iPS are identical, thus Tg methods could not be employed to assess miscibility. Atactic PS/syndiotactic PS blends were also noted to be miscible with rejection of atactic PS in the interfibrillar region between the lamellar stacks of sPS [725]. 

Woo EM, Sun YS, Yang CP. Polymorphism, thermal behavior, and crystal stability in syndiotactic polystyrene vs. its miscible blends. Prog Polym Sci 2001 26 945-83. 

Hong, B.K., Jo, W.H., and Kim. J. (1998) Miscibility of syndiotactic polystyrene/ atactic polystyrene blends by crystallization kinetics and enthalpy relaxation. Pdymer, 39, 3753. 

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