A Solvent-Free Photochemical Route to Clickable Multifunctional Polyacrylic Elastomers

Multifunctional polyacrylic elastomers with ultra-strechability, hydrophobicity, self-healing, and adhesive properties have wide applications in wearable electronics, sensors, soft robotics, and biomedical science. However, it is challenging to integrate these functionalities into one material in a simple solvent-free approach. To address this challenge, we herein develop a two-step bulk photopolymerization method to make ultrastretchable, adhesive, self-healable, hydrophobicity-tunable elastomers by adding a small amount of 1-ethynylcyclohexyl acrylate (ECA) into a common acrylate, ethyl acrylate. ECA efficiently prevents uncontrollable solidification during the first step photopolymeriza-tion and acts as a cross-linker to make elastomers in the second step photocuring. When ECA increases from 0.5 to 3.3 mol %, the maximum strain of elastomers decreases from 3087 to 1763% and the maximum stress increases from 0.19 to 1.04 MPa. These elastomers show a peeling strength of 1233-1621 N/m when adhering to different surfaces, including glass, steel, and polymethyl mathacrylate . They can self-heal to its original modulus with a fracture strain of 1100% and fraction stress of 0.5 MPa. In addition, we can use surface photoclick thio-yne reactions to tune the hydrophobicity with contact angles from 113 degrees +/- 2 degrees to 79 degrees +/- 2 degrees. We believe that our environmental-friendly solvent-free approach toward multifunctional polyacrylate elastomers will expand their applications in various areas.

Automated summary

This study develops a two-step bulk photopolymerization method to make multifunctional polyacrylic elastomers with ultra-strechability, hydrophobicity, self-healing, and adhesive properties. By adding a small amount of 1-ethynylcyclohexyl acrylate (ECA) into a common acrylate, these elastomers can be produced with desired properties. The environmental-friendly solvent-free approach expands their applications in various areas.