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

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