Effect of molecular weight on vitrification kinetics and molecular mobility of a polymer glass confined at the microscale

Molecular mobility and crystallization of renewable poly(ethylene furanoate) in situ filled with carbon nanotubes and graphene nanoparticles

“…It is also interesting to comment on the overshoot at the high temperature side of glass transition in Figure 2b. The overshoot has been connected to the high degree of freedom of a polymer 80 and, additionally, to the structural relaxation 81 . In the case of PNCs with strong attractive interfacial interactions, this overshoot is suppressed or even vanished 82 (and references therein), indicating partial loss of motions freedom for the bulk-like polymer chains.…”

Impact of bottlebrush chain architecture on Tg‐confinement and fragility‐confinement effects enabled by thermo‐cleavable bottlebrush polymers synthesized by radical coupling and atom transfer radical polymerization

“…[30,37,38] Extensive experimental studies have focused on the T g behavior of films of linear, freely deposited polymers as a function of nanoscale confinement. [1][2][3][4][5][6][7]9,10,[15][16][17][18][19][20][21]27,30,[31][32][33][34][35][36]38] A simple yet incomplete explanation for such T g -confinement effects has been posited in many of these studies: the presence of the free surface provides additional mobility relative to bulk behavior and leads to a T g decrease in sufficiently thin films which lack significant attractive-polymer substrate interactions; when strong attractive polymersubstrate interactions exist, such as hydrogen-bonding, they may overwhelm the effect of the free surface and lead to a T g increase in films of similar nanoscale thickness. [1,2,3,5,[15][16][17][19][20][21] We note that recent molecular dynamics simulations have indicated that the spatial extent of collective motion (associated with T g ) in the free-surface interfacial region of a thin film is not altered within simulation uncertainty from the film interior, but the simulations do provide support for a large interfacial mobility gradient.…”

“…In comparison with bulk films of the same polymer, thin films of linear, freely deposited polymers that are a few tens of nanometers thick may exhibit significantly different properties, for example, glass transition temperature ( T g ), fragility, and stiffness among others. [ 1–48 ] For instance, in comparison with a bulk polystyrene (PS) film and as measured by ellipsometry, a 21‐nm‐thick, substrate‐supported high molecular weight (MW) PS film exhibits a T g reduction of 10°C. [ 18 ] Understanding such nanoscale T g ‐confinement effects in polymers is important for many advanced technological applications, for example, thin films used in nanolithography processes for microchip manufacturing.…”

Kinetics of the glass transition of styrene‐butadiene‐rubber: Dielectric spectroscopy and fast differential scanning calorimetry

“…23 There are many reports of FDSC measurements of the cooling rate dependence of vitrification on polymers with a high-glass transition temperature (thermoplastics). 21,[24][25][26] To the best of our knowledge, FDSC measurements on vulcanized rubbers have not been previously published. The reasons could be the relatively small dynamic range due to their low-glass transition temperature, and problems regarding sample preparation.…”

“…There are many reports of FDSC measurements of the cooling rate dependence of vitrification on polymers with a high‐glass transition temperature (thermoplastics) 21,24–26 . To the best of our knowledge, FDSC measurements on vulcanized rubbers have not been previously published.…”