Chain-length dependence of the glass transition temperature

Comparison of mechanical and dielectric relaxation processes in laser-deposited poly(methyl methacrylate) films

“…Since the number of monomer units is larger than 4000 in the bulk material and about 60 in the film as has been observed using size exclusion chromatography [17], the glass transition is shifted to lower temperatures in the film. With an empirical model [22], the expected shift due to the chain length dependence can be calculated to be about 20 K. This is precisely what is observed here. The crucial point, however, is that the kink is visible in the mechanical loss but not in the dielectric measurement.…”

Synthesis, characterization, and glass transition temperature of poly(styrene‐b‐butyl methacrylate) block copolymers by stable free radical polymerization

“…The experimental values are higher than the theoretically fitted by O'Driscoll and Sanayei. 22 This feature has been also observed in the poly-4-hydroxystyrenes glass transition temperatures 23 where narrow poly-4-hydroxystyrenes obtained by stable free radical polymerization exhibit higher T g s than the broad poly-4-hydroxystyrenes obtained by classical radical polymerization over the entire range of molecular weights investigated. This fact was attributed to a probable decrease in the free volume.…”

“…There are different empirical models 19 -22 to describe the glass transition temperature dependence with the chain length, so there is no simple consensus on the subject. O'Driscoll and Sanayei 22 have studied different sets of vinyl polymers, i.e., polystyrenes, which have been theoretically well fitted. Figure 6 also includes the polystyrene fitted curve obtained by these authors.…”

Atom-Transfer Radical Polymerization of Dimethyl Itaconate

“…There are different empirical models [25 -28] to describe the glass transition temperature dependence with the chain length, so there is no simple consensus on the subject. In this case the O'Driscoll and Sanayei's approximation [28] has been used, which describes the variation of T g with molecular weight, M -n , as follows:…”