Conformational energy inversion in PMMA crystals prepared via thermal quenching with entropy diluents

Abstract

This study investigates the conformational structure of hypocrystalline poly(methyl methacrylate) (PMMA) films (hc-PMMAs) prepared via thermal quenching with benzoic acid (BA) as an entropy diluent. FT-IR spectroscopy revealed a significant increase in the trans-gauche (tg) conformation in hc-PMMAs compared to their solution-cast PMMA counterparts. The presence of BA stretched the polymer chains, promoting crystallization. Conformational energy calculations showed that the tg conformation became more stable than the trans-trans (tt) form, contrary to natural PMMA, due to chain stress from the quenching process. Thermal analysis demonstrated a unique tg plateau below the glass transition temperature (Tg), followed by relaxation to tt above Tg. These findings highlight the potential for manipulating polymer conformation and crystallinity using entropy diluents.