Title: Photo-Induced Bending Behavior of Post-Crosslinked Liquid Crystalline Polymer/Polyurethane Blend Films

Author: Xinlei Pang, Bo Xu, Xin Qing, Jia Wei*, Yanlei Yu*

Journal: Macromol. Rapid Commun., 2018, 39(1), 1700237

Abstract:

Photoresponsive blend films with post-crosslinked liquid crystalline polymer (CLCP) as a photosensitive component and flexible polyurethane (PU) as the matrix are successfully fabricated. After being uniaxially stretched, even at low concentration, the azobenzene-containing CLCP effectively transfers its photoresponsiveness to the photoinert PU matrix, resulting in the fast photo-induced bending behavior of whole blend film thanks to the effective dispersion of CLCP. Specifically, the blend film shows photo-induced deformations upon exposure to unpolarized UV light at ambient temperature. The film unbends after thermal treatment, and the randomly orientated mesogens in the film can be realigned by the mechanical stretching, which endows the film with a reversible deformation behavior. The photosensitive blend film possesses favorable mechanical property and good processability at low cost, and it is a promising candidate for a new generation of actuators.

Fulltext Link: https://onlinelibrary.wiley.com/doi/full/10.1002/marc.201700237

In this work, through incorporating crosslinkable PAZO bearing N-hydroxysuccinimide carboxylate substituted azobenzene moieties to PU, we fabricated photoresponsive blend films with post-crosslinked liquid crystalline polymer (CLCP) as a photosensitive component and flexible polyurethane (PU) as the matrix. Upon UV (365 nm) irradiation at low intensity, the small volume change induced by the aligned azobenzene moieties could be amplified to the whole blend system due to the effective dispersion of CLCP in the PU matrix. It is worth noting that the blend film (PAZO/PU = 1.7/98.3) with a lower content of PAZO was also able to undergo fast photo-induced bending behaviors upon exposure to UV light at ambient temperature.