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With increasing demand for scratch-resistant flexible electronics, the development of transparent coatings with good scratch resistance and self-healing properties has emerged as a key research topic. In this study, a high-strength self-healing poly(urethane – urea) (PUU)-based nanocomposite coating was prepared by introducing functionalized nanodiamond (ND) into a PUU matrix via solution blending. The PUU matrix had hard-segment repeating units and was constructed using isophorone diamine and isophorone isocyanate. The ND particles were modified using a silane coupling agent, 3-aminopropyltriethoxysilane, to obtain well-dispersed KH-ND nanoparticles. KH-ND promoted microphase separation in the PU matrix, inducing the formation of dense and homogeneous hard domains that dissipated stress, prevented further crack development, and improved the mechanical properties and scratch resistance of the coating. In addition, the coating exhibited excellent self-healing properties. Fourier-transform infrared spectroscopy, scanning electron microscopy, and atomic force microscopy were used to characterize the self-healing and hardening mechanisms of the coating. The environmentally friendly PUU/KH-ND coating is easy to prepare and has broad application prospects in transparent and anti-scratch coatings for flexible electronics, automobiles, and home appliances. [ABSTRACT FROM AUTHOR]

This study used expectancy-value theory to better understand no-fee teacher education and improve the relevant educational methods and policies. It applies a self-developed scale, derived from the theory, to identify entry motivation and professional satisfaction levels among no-fee teacher education students (N = 700) at Southwest University. The results illustrate that (1) students enrolling in the no-fee teacher education program are mainly motivated by their perception of the teaching profession, no-fee teacher education policies, intrinsic value, and social persuasion; (2) demographic characteristics account for the differences between no-fee teacher education students in respect to entry motivation and professional satisfaction; and (3) specific entry motivation has significant predictability for the level of professional satisfaction of students. With solid empirical data as evidence, this study recommends that no-fee teacher education policymakers and program designers should take cognizance of the motivating factors that affect students' decision to enroll in the program and their perception about the teaching profession after years of preparation; information about student needs and feedback should be incorporate in modifying policy and implementing educational practices in order to maximize the effectiveness of the no-fee teacher education policy.