Relaxation behavior of polymer thin films: Effects of free surface, buried interface, and geometrical confinement

Investigation of the Atmospheric Moisture Effect on the Molecular Behavior of an Isocyanate-Based Primer Surface

“…A picosecond SFG system was used for experiments in this study (EKSPLA, Lithuania, model PL2231-20-RS232). SFG vibrational spectroscopy was extensively used to probe the surfaces and interfaces of the materials due to its intrinsic surface sensitivity. − SFG theories, setups, and instrumentation will thus not be stated in detail. Briefly, two input beams, a visible beam with a fixed wavelength at 532 nm and a frequency-tunable infrared (IR) beam, were overlapped spatially and temporally on the surfaces of the samples.…”

“…Sum frequency generation (SFG) vibrational spectroscopy has been demonstrated to be a suitable tool to understand the change of molecular structures of surfaces and interfaces. − SFG enables precisely measuring the molecular structure/behavior of surfaces/interfaces by its surface/interface-sensitive nature. − SFG has been extensively applied to study the surface and interfacial molecular structures of polymers, including various polymer adhesives. − ,− In this study, the atmospheric moisture effect on the surfaces of isocyanate-based primers was probed by SFG, and the molecular behaviors of such surfaces were correlated to the macroscopic properties to investigate the relationship. Different conditions in the experiments were set up in a variation of humidity levels and exposure time to understand the influences of their effects on the primer surfaces.…”

Toposelective vapor deposition of hybrid and inorganic materials inside nanocavities by polymeric templating and vapor phase infiltration

“…Previously, ALD and VPI have led to different degrees of inltration inside non-constrained polymeric templates, 47 but in this study, the difference was relatively small, which was partially attributed to higher temperature during the shortpulse protocol. Furthermore, the maximum inltration was limited inside the most constrained cavities due to connement effects, e.g., reduced polymer chain mobility 48 and limited space for swelling. The hybrid materials were further calcined into toposelective inorganic structures that were typically either cavity-lling porous deposition, cavity-bridging lms with various degrees of anisotropic cracking, or particulate deposition inside the cavities.…”

Effect of Oligomer Segregation on the Aggregation State and Strength at the Polystyrene/Substrate Interface

“…Polymer chains in contact with an inorganic solid often exhibit peculiar properties that deviate from those in bulk, owing to the interaction between the polymer and the solid surface . After thermal annealing, interfacial polymer chains are adsorbed onto the solid surface and form an adsorbed layer that cannot be removed even after leaching in a good solvent. − The adsorbed layer consists of two types of chains with different conformations: a “tightly adsorbed layer” (also called a “flatten layer”) and a “loosely adsorbed layer”. − The tightly adsorbed chain is in direct contact with the solid and strongly adsorbed with many adsorption points and flatten chain conformations.…”

“…We focused on the variation in the adhesion strength of PS due to the change in interfacial aggregation states caused by the segregation of the PS oligomer. PS was chosen as the typical amorphous polymer because it has been widely studied for its physical properties at solid interfaces. , The oligomer in the PS matrix is expected to spontaneously segregate in the interfacial region near the solid interface because of the entropic effect during thermal annealing at a temperature higher than T g . − This will change the aggregation state of PS at the interface, which in turn changes its adhesion behavior on a substrate.…”