Wrapping of polyrhodanine onto tubular clay and its prominent effects on the reinforcement of the clay for rubber

Polyrhodanine (PRd) was wrapped onto the surface of halloysite nanotubes (HNTs) through the oxidative polymerization of rhodanine on Fe3+-impregnated-HNTs. The wrapping mechanisms were disclosed. The PRd-HNTs exhibited a prominent reinforcing effect for rubber. With the incorporation of 30 phr of PRd-HNTs, the tensile strength was increased by almost 8-fold, and the modulus (at 300% strain) was increased by 257% compared to neat SBR. More strikingly, with only 2.9 wt.% of PRd (relative to HNTs), the tensile strength and modulus of the composite were enhanced by 117% and 87%, respectively, suggesting the high efficiency of the modification. Such profound changes in the reinforcement were attributed to the formation of covalent linkages between PRd-HNTs and rubber through the participation of PRd-HNTs in curing process. In view of the versatility of PRd-wrapping procedure, this method offers significant insight into the interfacial design of rubber nanocomposites consisting of nonpolar matrices and inorganic reinforcements.