The conformation of atactic poly(methyl methacrylate) (a-PMMA) freeze-extracted from solvents of various molecular size was investigated by IR and Raman spectroscopy. IR studies showed that self-aggregates and partial helix conformation of polymer chain existed in the annealed a-PMMA sample freeze-extracted from a-PMMA/poly(ethylene glycol) (PEG) solution. Temperature dependence of IR I-1240 (cm-1)/I-1270 (cm-1), ratio indicated that a-PMMA freeze-extracted from PEG had lower backbone conformational energy than that from dioxane, FT-Raman spectroscopies showed that strong interaction existed between a-PMMA and dioxane, while little solute-solvent interaction existed in the a-PMMA/PEG system. (C) 2001 Elsevier Science Ltd. All rights reserved.