Natural cardanol modified liquid polyisoprene rubber and its surface adhesion performance

Inspired by mussel protein, the adhesives based on dopamine boom due to its perfect adhesion performance. However, limited by its high price, it is of great significance to study adhesives originated from natural and renewable phenolic and polyphenol compounds which structure is similar to dopamine. The application of natural products can also reduce the consumption of non-renewable petrochemical resources. Herein, the agriculture and forestry by-products cardanol (CA) was grafted onto liquid polyisoprene rubber (LIR) molecular chains to improve its surface energy. Then, the grafting product (LCA) experienced complex formulation (GLCA) and vulcanization (v-LCA). The vulcanization crosslinking was confirmed by the weakening of double bonds absorption in IR spectra and C-C peak in XPS spectra, the enhancement of methyl proton in the α-position of quaternary carbon atom in 1 H NMR spectra. The GLCA adhesive agent showed good adhesion performance on wet polar substrates because the drainage effect of LIR and the alkyl chains of CA. Moreover, CA provides the possibility of the multiple interactions as metal bonding, hydrogen bonding , cation-π interaction, π-π stacking, hydrophobic interaction and entanglement between chains. The v-LCA adhesive layer exhibits good solvent resistance . This study provides a prospect of the natural phenolic compounds from agriculture and forestry by-products to be used in the wet adhesion of industry, agriculture, or daily life.