A detailed investigation of the free radical copolymerization behavior of n -butyl acrylate macromonomers

The free radical copolymerization of macromonomers with low molecular weight monomers represents a versatile tool for the formation of statistical copolymers featuring pendant side chains. In the current study n-butyl acrylate macromonomer (BAMM) has been synthesized via high temperature acrylate synthesis in a one-pot-one-step procedure and copolymerized with benzyl acrylate (BzA) as a comonomer up to 40% conversion in a free radical copolymerization with 1,1′-azobis(isobutyronitrile) (AIBN) as a source of radicals. The copolymers poly(BAMM)-co-poly(BzA) are fully characterized via size exclusion chromatography (SEC), nuclear magnetic resonance spectroscopy (NMR), and liquid adsorption chromatography at critical conditions (LACCC). The achievable molecular weight of the synthesized poly(BAMM)-co-poly(BzA) lies between 8000 and 77000 g mol^-1 with a polydispersity of 1.30-2.12. Calculated copolymer compositions from the integrals of the specific resonances H _ar and CH₂ of the BzA compared to CH₂ of the BAMM have been subjected to a (terminal model) Mayo-Lewis analysis, resulting in estimated reactivity ratios at ∼40% conversion of r_BzA = 2.46 and r_BAMM = 1.79, indicating a copolymer composition of F _BA < 0.65 for the copolymers derived from f_BzA > 0.9 up to a copolymer composition of F_BA > 0.9 for copolymers with a comonomer feed of f_BzA < 0.6. The poly(BAMM)-co-poly(BzA) have been analyzed under critical conditions of n-butyl acrylate (BA) on a normal phase column to obtain an image of the generated poly(BAMM)-co-poly(BzA).