Polymer class specificity of the glass temperature

Chain‐Length‐Dependent Termination in Radical Polymerization of Acrylates

“…[51] This means that at a given temperature the acrylates are more flexible, which should allow them to start behaving as long chains at a lower chain length, and hence have a lower i c . formation.…”

“…[36] In fact T g decreases by more than 150 °C in going from p(MMA) to p(DMA). [51] Referring to Table 1 from acrylate to acrylate. Probably the just-described situation with SP PLP EPR reflects that intra-family variation of i c is determined by more than just T g , although resolving this will have to wait until i c is measured more precisely.…”

Glass transition temperature prediction of polymers through the mass-per-flexible-bond principle

“…Here we limit our discussion to the perhaps the most important factor, the chemical structure. An empirical parameter that quantifies the influence of structure on chain flexibility was proposed by Di Marzio [14] and further developed by Schneider and Di Marzio [15][16][17] is the mass-per-flexible-bond of a polymer repeat unit (abbreviated as M/f). This is the mass of a monomer divided by the number of flexible bonds in it.…”

“…This is the mass of a monomer divided by the number of flexible bonds in it. (M/f) is a simplified representation of the polymer's conformational entropy, and as such there is a linear correlation between this value and the polymer's T g , as expressed in Equation (1) [16], (1) where T g is the glass transition temperature of polymer (in K), M is the molecular weight of the polymer repeat unit (in g/mol), f is the "number "of flexible bonds in the repeat unit, and (M/f) P is the mass-per-flexible-bond of the (average) repeat unit. The coefficients A and C are polymer class specific constants that originate from the different densities, steric hindrances and intermolecular interactions of chemically distinct polymers, the factors that collectively affect the cooperative segmental mobility and hence determine the T g .…”

“…It should be emphasized f is an effective number of "flexible" bonds contributing by rotation to the conformational changes of the repeat unit due to known steric effects and unknown barriers due to inter/intramolecular interactions [16]. As such, M/f does not depend on the thermodynamic state of the system; rather it signifies the ability to promote energetically stimulated rotations to release stresses [18].…”