Grafting–through Strategy in Emulsion: An Eco–friendly and Effective Route for the Synthesis of Graft Copolymers

Brush-like and centipede multigraft copolymers of poly(n-butyl acrylate)–g–poly(styrene) were synthesized via seeded emulsion polymerization under 1,1-diphenylethylene (DPE) and miniemulsion polymerization. Single-tailed and double-tailed poly(styrene) macromonomers were prepared by DPE-technique in emulsion and Steglich esterification. Then poly(n-butyl acrylate)–g–poly(styrene) multigraft copolymers were obtained by miniemulsion copolymerization. The molecular characteristics of poly(styrene) macromonomers and poly(n-butyl acrylate)–g–poly(styrene) have been characterized by gel permeation chromatography. The weight content of poly(styrene) and the number of branch points in brush-like and centipede multigraft copolymers were calculated by proton nuclear magnetic resonance, and the maximum number of branch points is 47. Differential scanning calorimetry analysis and morphological observations by atomic force microscopy confirmed microphase separation in poly(n-butyl acrylate)–g–poly(styrene). Tensile properties showed that brush-like and centipede multigraft copolymers had characteristics of TPEs when the weight content of poly(styrene) in poly(n-butyl acrylate)–g–poly(styrene) was 23 %∼37 %. And centipede multigraft copolymers showed better elastic properties than brush-like multigraft copolymers, which was in line with our previous work.