N.m.r. study of hydrogen bonded polymer blends: influence of the tacticity of poly(methyl methacrylate) on its miscibility with poly(styrene- co-vinylphenol)

Abstract

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 13C 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 ( T H 1 ϱ ), or a dimensional scale of about 2 nm, for all compositions studied except for 70 30 MPS-5 PMMA-i , which shows a single T H 1 ϱ . 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.