NMR-STUDY OF HYDROGEN-BONDED POLYMER BLENDS - INFLUENCE OF THE TACTICITY OF POLY(METHYL METHACRYLATE) ON ITS MISCIBILITY WITH POLY(STYRENE-CO-VINYLPHENOL)

The miscibility of poly(styrene-co-vinylphenol) containing 5% vinylphenol monomer units (MPS-5) with syndiotactic poly(methyl methacrylate) (PMMA-s) and with isotactic poly(methyl methacrylate) (PMMA-i) was studied with C-13 solid state n.m.r. complemented with cloud point and differential scanning calorimetry measurements. Above room temperature, the results indicate that the PMMA-s blends have a wider composition range over which the system exists in a single phase. In the time scale of spin-lattice proton relaxation, or a dimensional scale of about 25 nm, PMMA-s is miscible with MPS-5 in all compositions studied, namely 30, 50, and 70 wt% of MPS-5; PMMA-i is miscible only at one composition, namely 70% styrene copolymer. Both PMMA-s and PMMA-i blends indicate the existence of heterogeneities in the time scale of rotating frame spin-lattice relaxation (T1rho(H)), or a dimensional scale of about 2 nm, for all compositions studied except for 70/30 MPS-5/PMMA-i, which shows a single T1rho(H). The glass transition temperature data of these blends are consistent with the n.m.r. observation. The cloud point diagram is also in agreement with n.m.r. results.