Similarity of glass transition anomalies in fullerene core polymer stars and block copolymers

Glass transitions have been studied by differential scanning calorimetry (DSC) in atactic polystyrene (PS) and polydimethylsiloxane (PDMS), when covalently attaching their chains differing in length to 'rigid walls,' fullerene C-60 (Or C-70) 'balls' in stars or polyimide (PI) blocks in block copolymers. A number of common anomalies were observed including complication and multiple broadening of the glass transition range, both to higher and lower temperatures, decreases in activation parameters, arising out of the heterogeneity of segmental dynamics, The results are interpreted as proceeding from (a) the common segmental origin of alpha- and beta-relaxations and a breakdown of intermolecular cooperativity of segmental motions; (b) confinement of chains to nanometer-scale spaces, and (c) the 'rjgid wall' effect. (1998 Elsevier Science B.V. All rights reserved.