Poly(butyl acrylate-co-fluorinated acrylate)-graft-natural rubber: Synthesis and application as compatibilizer for natural rubber/poly(butyl acrylate-co-fluorinated acrylate) films

Poly(butyl acrylate-co-fluorinated acrylate)-graft-natural rubber was successfully prepared via emulsion graft copolymerization and applied as a compatibilizer for improving phase compatibility and toughness of natural rubber/poly(butyl acrylate-co-fluorinated acrylate) films. From graft copolymerization step, butyl acrylate (BA) acted as a co-monomer to be initially grafted onto the natural rubber (NR) and then copolymerized with 2,2,2-trifluoroethyl methacrylate (3FMA) to form a grafting poly(BA-co-3FMA) chain onto the NR backbone. The appropriated BA/3FMA ratio at 30/70 (w/w) provided the highest graft copolymer fraction of 72.8 wt% with 25.3 mol% grafted 3FMA and 68.5% grafting efficiency under center reaction condition. Transmission electron microscopy analysis indicated that the graft product had core-shell morphology, which NR was a core and covered by poly(BA-co-3FMA) shell. The results from Molau test and atomic force microscopy showed that the addition of 5-10 wt% graft product could enhance the compatibility between NR and poly(BA-co-3FMA) phases in the NR/poly(BA-co-3FMA) films (20/80 (w/w)) and provided the obtained films with a greater elongation at break to 266% than that of poly(BA-co-3FMA) film (27%). The compatibilized films also exhibited a high hydrophobicity (water contact angle = 109 degrees) and oleophobicity (hexadecane contact angle = 54 degrees) with a low surface energy (8.04 mN/m), which can be further applied as self-sealing films for moisture and oil protection.