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 77 000 g mol –1 with a polydispersity of 1.30–2.12. Calculated copolymer compositions from the integrals of the specific resonances H ar and C H 2 of the BzA compared to C H 2 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).