Coil to globule transition behaviour of poly(methyl methacrylate) in isoamyl acetate

Abstract

The coil–globule transition behaviour of poly(methyl methacrylate) has been studied in isoamyl acetate by using the dynamic light scattering technique. The dimensions of the polymer show smooth and continuous contraction below θ temperature (61.0°C). The hydrodynamic size of PMMA in isoamyl acetate ( M w=3.3×10 6 g mol −1) decreases to 41% in an unperturbed state at 18.4°C. The temperature dependence of a chain contraction can be represented by a master curve in α h 3∣ τ∣ M w 1/2 vs ∣ τ ∣ M w 1/2 plot, where α h= R h/ R h, θ and τ=( T− θ)/ θ. A high-chain density value implies that the highly collapsed globule contains 56% isoamyl acetate in its hydrodynamic volume.