Grafting polyisoprene onto surfaces of nanosilica via RAFT polymerization and modification of natural rubber

Abstract

In this contribution, we reported the investigation of natural rubber (NR) reinforced by silicon dioxide‐graft‐polyisoprene (SiO2‐g‐PIP) core–shell nanoparticle. First, the hydroxyl on the surface of the SiO2 nanoparticles was reacted with 2‐methyl‐2‐[(dodecylsulfanylthiocarbonyl) sulfanyl] propanoic acid to produce trithioester‐capped SiO2 (denoted as SiO2‐CTA). SiO2‐CTA was used as a nanoparticle chain transfer agent, and SiO2‐g‐PIP core–shell nanoparticles were synthesized via reversible addition‐fragmentation chain transfer polymerization (RAFT). The results of FTIR spectroscopy and TGA showed that the grafting weight of the PIP block in SiO2‐g‐PIP was 2.1 wt%. SiO2‐g‐PIP and SiO2 were simultaneously incorporated into NR. The curing properties of the NR compounds showed that the vulcanization rates of the NR/SiO2‐g‐PIP compounds were much higher than those of NR/silica compounds. The results of scanning electron microscopy showed that SiO2 microdomains in the NR/SiO2‐g‐PIP vulcanizate were much better disperse and distribute than SiO2 microdomains in the NR/SiO2 composite. The filler–rubber interaction of the NR/SiO2‐g‐PIP composite endowed the composite with improved mechanical properties. POLYM. ENG. SCI., 59:1167–1174 2019. © 2019 Society of Plastics Engineers