Reactivity ratios and properties of copolymers of 2-ethoxyethyl methacrylate with dodecyl methacrylate or styrene

Abstract

The copolymerization reactivity ratios for 2-ethoxyethyl methacrylate (EOEMA) with dodecyl methacrylate (DDMA) or styrene (ST) were estimated. Polymerization was performed by using tert-butyl peroxy-2-ethylhexanoate (0.01 mol dm−3) as initiator, isothermally (70 °C) to low conversions (< 10 wt.%) in a wide range of copolymer compositions (every 10 mol-% steps). For the DDMA/EOEMA copolymerization both monomers prefer to react with EOEMA: r (DDMA) = 0.82 and r (EOEMA) = 1.26 with r (DDMA) × r (EOEMA) = 1, which results in the random copolymerization. For the ST/EOEMA copolymerization reactivity ratios are r (ST) = 0.59 and r (EOEMA) = 0.49 indicating a higher reactivity with opposite monomer, while the alternation tendency is not highly pronounced. The probabilities for formations of dyad and triad monomer sequences in dependence on monomer compositions were calculated from the obtained reactivity ratios. With the share increase of ST or DDMA in copolymers surface properties changed from hydrophilic to hydrophobic. Glass transition temperature of copolymer increased with the increase of ST and decrease of DDMA. The molar mass distribution and thermal degradation of synthesized copolymers were also determined and discussed. The reactivity ratios enable optimization of copolymer properties for a given application as polyelectrolytes, drug delivery systems and multifunctional additives for improvement of rheological properties of lubricating oils.