Confined Glassy Dynamics in a Star-Shaped Polymer Induced by Crystallization: Case Study of Polyhedral Oligomeric Polysilesquioxane—Isotactic Polystyrene (POSS-iPS)

Crystallizability of Free and Tethered Chains in Nanometer‐Sized Droplets

“…In this regard it is worthwhile to note that polymer‐grafted nanoparticles do show a crystallization of the polymer chains in some instances, [ 1,35–37 ] which demonstrates that reduced chain mobility does not necessarily exclude the formation of crystals. However, a significant difference in these systems is that chains meet from multiple directions, i.e., a chain grafted to a particle can not only aggregate with its neighbors from the same particle but also with those from other particles in its vicinity.…”

“…This allows to determine the crystallinity and monitor the kinetics of the process from the difference between initial and current relaxation strength. [1,36,37] However, this approach required an isothermal measurement (since the relaxation strength is temperature dependent) at a temperature at which the relaxation process was in the accessible frequency range.…”

“…In fact, literature provides examples of either, absence of crystallization in polymer chains grafted to nanoparticles if the grafting density is low [35] as well as reduced or no crystallization of polymer confined to nanopores when the (densely packed) chains are adsorbed to the pore walls. [49] In this regard it is worthwhile to note that polymer-grafted nanoparticles do show a crystallization of the polymer chains in some instances, [1,[35][36][37] which demonstrates that reduced chain mobility does not necessarily exclude the formation of crystals. However, a significant difference in these systems is that chains meet from multiple directions, i.e., a chain grafted to a particle can not only aggregate with its neighbors from the same particle but also with those from other particles in its vicinity.…”

“…Polymer crystallization has been the focus of scientific research for decades, and our understanding of the fundamentals of the process and its consequences for applications has improved a lot. Nevertheless, despite tremendous efforts, certain aspects are yet to be unravelled, e.g., details of the structure formation predating the actual crystalline order and the kinetics of its formation, [1,2] special types of surface-induced crystallization [3][4][5][6][7] or alterations due to spatial confinement. [8][9][10] Especially the latter gained more interest in recent years, on the one hand, because experimental DOI: 10.1002/macp.202200452 accessibility increased due to technological improvement.…”

“…[13,14,33] Even under more severe constraints on the nanoscale crystallization can be observed, e.g., in polymer chains grafted to the surface of nanoparticles; although often used as nucleations agents in a nanoparticle-polymer blend, [34] a few studies also investigate the crystallizability of the grafted chains. [1,[35][36][37] However, these systems strongly restrict chain motion and position, which are crucial in order to transport chains to the growing edge of the crystallite and establish crystalline intermolecular alignment, respectively. Hence, such constraints typically alter the crystallization process, e.g., crystallinity may be reduced [35,36] or suppressed completely if the grafting density is too low.…”