Amphiphilic Poly(β-Myrcene- co-Acrylic Acid) Copolymers Synthesized by Nitroxide-Mediated Copolymerization as Stabilizers of Terpene-Based Waterborne Latex

Abstract

Terpene-based amphiphilic copolymers have been designed as biobased stabilizers for waterborne latex synthesized by miniemulsion or emulsion polymerization of 1,3-diene terpene monomers. The pH-responsive P(AA-co-My) amphiphilic copolymers were synthesized by nitroxide-mediated radical copolymerization of β-myrcene (My) and acrylic acid (AA) with reactivity ratios of r_My = 0.24 ± 0.06 and r_AA = 0.05 ± 0.10. Polymerization was controlled for My-rich monomer feed ratios (f_My,0 > 0.3). Though AA NMP exhibited reasonable control, a low fraction of My (f_My,0 ≤ 0.3) produced branched structures with higher molar masses. P(AA_0.80-co-My_0.20) was the most efficient copolymer to stabilize monomodal PMy latexes (D_h ∼ 150-350 nm) synthesized by miniemulsion or emulsion polymerization. P(AA-co-My) copolymers with a higher hydrophobic PMy fraction (>35 mol %) were less efficient stabilizers. The more hydrophobic β-farnesene monomer was successfully polymerized by miniemulsion polymerization, whereas emulsion polymerization failed. The biobased waterborne latexes are pH-responsive with pH-triggered flocculation at low pH.