Controlled synthesis of isotactic and symmetrical poly(methyl methacrylate) directed toward uniform polymers with high crystallinity

Abstract

The synthesis and fractionation by supercritical fluid chromatography (SFC) of an isotactic and symmetrical poly(methyl methacrylate) (PMMA) containing very few configurational defects, H–(–MMA–)–CH3 (2), are described. Detailed analysis by 1H NMR spectroscopy showed that the PMMA 2 was almost perfectly isotactic (∼100%) except a small amount (11%) of racemo sequence at the first tactic diad from the initiating chain-end. The uniform PMMAS 2 with 31, 36, 41, and 44 repeating units (n) had melting points higher by 4.5—12.2°C than those of the uniform PMMAS prepared in a previous work, t-C4H9–(–MMA–)–H (1) with a triad isotacticity of 96.1%. The degrees of crystallinity of the uniform PMMA 2 samples were determined to be 92—97%, also high as compared with those of uniform PMMA 1 samples. Single crystals were grown from a solution of the 7mer of 2(n=7), and the crystal structure was determined by X-ray analysis. © 1995, The Society of Polymer Science, Japan. All rights reserved.