Dynamic light scattering studies of atactic and syndiotactic poly(methyl methacrylate)s in dilute theta solution

✍ Scribed by E. Elif Gürel; Nilhan Kayaman; Bahattin M. Baysal; Frank E. Karasz

• Publisher: John Wiley and Sons
• Year: 1999
• Tongue: English
• Weight: 166 KB
• Volume: 37
• Category: Article
• ISSN: 0887-6266
• DOI: 10.1002/(sici)1099-0488(19990815)37:16<2253::aid-polb27>3.0.co;2-l

✦ Synopsis

The present article considers the coil-to-globule transition behavior of atactic and syndiotactic poly(methyl methacrylates), (PMMA) in their theta solvent, n-butyl chloride (nBuCl). Changes in Rh in these polymers with temperature in dilute theta solutions were investigated by dynamic light scattering. The hydrodynamic size of atactic PMMA (a-PMMA-1) in nBuCl (M w : 2.55 ϫ 10 6 g/mol) decreases to 61% of that in the unperturbed state at 13.0°C. Atactic PMMA (a-PMMA-2) with higher molecular weight (M w : 3.3 ϫ 10 6 g/mol) shows higher contraction in the same theta solvent (␣ ϭ R h (T)/R h () ϭ 0.44) at a lower temperature, 7.25°C. Although syndiotactic PMMA (s-PMMA) has lower molecular weight than that of atactic samples (M w : 1.2 ϫ 10 6 ), a comparable chain collapse was observed (␣ ϭ 0.63) at 9.0°C.