Direct Observation of Conformational Relaxation of Polymer Chains at Surfaces

Abstract

Sum-frequency generation spectroscopy was employed to follow the conformation evolution of polystyrene chains at the surface of a spin-coated film in a temperature-ramping mode as well as under isothermal annealing. The conformation of surface chains in an as-cast film was observed to be in a nonequilibrium state, in accordance with reported results for polymer chains in thin spin-coated films. While the relaxation of surface nonequilibrium chains was induced by the enhanced surface mobility, the whole chain motion such as reptation might be a key factor in determining the time scale for equilibrating the surface chain conformation.

Effect of Molecular Architecture on Conformational Relaxation of Polymer Chains at Interfaces

“…In this case, the tilt angle of phenyl rings at the quartz interface with respect to the normal direction was calculated to be less than 20°. [ 42,43 ] This is consistent with previously reported results. [ 5,16,44,45 ] After 1 h annealing, SFG spectra were basically similar in shape to one another.…”

“…In the case of 8sPS, signals at a wavenumber region centered 3010 cm −1 appeared to be slightly stronger than the baseline ones. However, since no vibration mode contributed from phenyl rings was observed in this wavenumber region, [ 43 ] it seems that the slight increase in signal at 3010 cm −1 was within the experimental accuracy. Taking into account our previous results, [ 5,16,44,45 ] the local chain conformation at the interface remained in a nonequilibrium state after annealing at 423 K for 1 h, regardless of the molecular architecture.…”

Design Principles of Interfacial Dynamic Bonds in Self‐Healing Materials: What are the Parameters?

“…While the former governs the segmental dynamics and mean square displacement of polymer chains, the latter decides the strength and conformational relaxations of the polymer chains. [38][39][40][41][42][43][44][45][46][47][48][49][50][51] Such a concept is critical to optimize the healing efficiency via interdiffusion of mobile polymer chains across the cut surfaces in addition to the supramolecular networks that exchange the newly formed dangling free groups (within the fracture region), enabling reconstruction. In this article, we outline the latest developments in self-healing polymers and SH-PNCs literature and provide insights into materials design and healing mechanisms.…”

Dynamics Gradient of Polymer Chains near a Solid Interface

“…Then, SFG spectroscopy, which provides the vibrational information with the best depth resolution among available techniques, − was conducted for a quantitative characterization of the relaxation dynamics of NBR chains strongly adsorbed on the SiO 2 interface. Panels (a) and (b) of Figure show SFG spectra for an NBR film annealed at various temperatures both in the CH and CN regions, respectively.…”