Synthesis of Hyperbranched Poly(n-nonyl acrylate) and its Crosslinking to form Organogels

(2-Bromo-n-nonan-1-oxycarbonyl)ethyl acrylate was synthesized as an inimer for self-condensing vinyl polymerization (SCVP) to produce hyperbranched poly(n-nonyl acrylate), either as a homopolymer or as a copolymer with n-nonyl acrylate. The inimer was homopolymerized and copolymerized by atom transfer radical polymerization (ATRP) and activator generated by electron transfer (AGET) ATRP to produce soluble polymers with broad polydispersities (up to Đ = 9.91), which is characteristic of hyperbranched polymers produced by SCVP. The resulting hyperbranched (co)polymers were crosslinked by atom transfer radical coupling (ATRC) in both one-pot and two-step procedures. The radical-radical crosslinking reaction is extremely efficient, resulting in hard plastic particles from the homopolymer of (2-bromo-n-nonan-1-oxycarbonyl)ethyl acrylate synthesized in bulk. Crosslinked organogels that swell in THF were formed when the rate of crosslinking decreased using acetonitrile solutions. Dynamic shear and stress relaxation experiments demonstrated that the dry network behaves as a covalently crosslinked soft gel and shows predicted behavior from theory of rubber elasticity, with a glass transition at -50 °C according to differential scanning calorimetry.