Fully Biosourced, Vulcanization-Free, and Thermal-Responsive Natural Rubber Material

Natural rubber (NR) material is indispensable in various fields of our daily life, while its preparation usually involves toxic cross-linking agents and energy-consuming vulcanization processes. The permanent cross-linking network of NR products also makes its degradation and recycling difficult. Herein, a fully biosourced, vulcanization-free NR material is developed by simply introducing carrageenan (KC) in the rubber matrix via a facile aqueous mixing method. The nonrubber components (NRCs) on the rubber latex particles are of crucial importance for this art as they can interact with KC by forming hydrogen bonding between the functional groups of proteins in NRCs and the abundant hydroxyl and sulfonate groups on KC molecules. As a result, KC is selectively dispersed between the latex particles and forms a segregated filler network. The special KC network and the good interfacial interaction between KC and rubber promote strain-induced crystallization and endow rubber composites with great mechanical properties. Moreover, the obtained NR/KC composites exhibit an interesting thermal-responsive attraction behavior, which has good potential in smart applications, such as artificial muscle. This work paves a simple and effective path to vulcanization-free NR by leveraging the inherent NRC on latex rubber particles, opening a new horizon for the sustainable development of NR/polysaccharide composite elastomers.