Youngnam Kim (1,2), Ki-Ho Nam (1), Yong Chae Jung (2), Haksoo Han (1)
Composites Part B, 203, October 2020. DOI: 10.1016/j.compositesb.2020.108451

Keywords

Multi-stimuli responsive, Self-healing, Interfacial adhesion, Bilayer polymer structure,Microencapsulation

Abstract

Simple self-healing behavior of polymers that respond to multiple physicochemical stimuli are highly desirable for industrial applications. In this study, under various external environmental stimulating factors, we focus on the self-healing kinetics of polymer bilayer films (PBFs) comprising a colorless polyimide (CPI) bottom-substrate layer and linseed oil loaded microcapsule (LOMC)-embedded polydimethylsiloxane (PDMS) upper-healing layer. The experimental results showed clear correlation between stimulating factors and the healing time. Although the crack-healing behavior of PBF with 5 wt% microcapsule under air atmosphere is fairly slow, it has an improved healing effect at the artificial crack interface heating to 70 °C; moreover, gradual healing is observed by moisture absorption in environments with relative humidity of 70%. Remarkably, we found that ultraviolet (UV)-light irradiation through the 5 wt% LOMC-filled PDMS layer triggers a noticeable kinematic advantage for the drying reaction that initiates interfacial self-healing. Short-time (20 min) UV-irradiated PBF 5 wt% exhibits a low water vapor permeability of 35.4 g m−2 day−1 and excellent healability with ~91% recovery by single capsule-type photochemical-induced self-healing. The proposed approach advances the extrinsic healing of colorless polymers in a kinetically effective way without compromising their chemical composition.

How Our Software Was Used

Dragonfly was used for 3D image reconstruction.

Author Affiliation

(1) Department of Chemical and Biomolecular Engineering, Yonsei University, 50 Yonsei-ro, Seodaemun-gu, Seoul, 120-749, Republic of Korea.
(2) Institute of Advanced Composites Materials, Korea Institute of Science and Technology, Chudong-ro 92, Bondong-eup, Wanju-gun, Jeollabuk-do, 565-905, Republic of Korea.