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The effect of hydrogen bonding on the copolymerization kinetics of 2-methoxyethyl acrylate with 2-hydroxyethyl methacrylate in alcohol and aqueous solutions
The Canadian Journal of Chemical Engineering ( IF 1.6 ) Pub Date : 2021-06-16 , DOI: 10.1002/cjce.24226
Maryam Agboluaje 1 , Robin A. Hutchinson 1
Affiliation  

The influence of alcohol and alcohol/water solutions on the radical copolymerization kinetics of 2-hydroxyethyl methacrylate (HEMA) with 2-methoxyethyl acrylate (MEA) is studied using pulsed-laser-polymerization coupled with size exclusion chromatography. It is found that MEA incorporation into the copolymer is increased in butanol, methanol (MeOH), and MeOH/H2O solutions relative to the bulk system. Copolymer composition can be represented for solvent levels ≥50 vol.% by a single pair of reactivity ratios (urn:x-wiley:00084034:media:cjce24226:cjce24226-math-0001 = 2.39 ± 0.16, urn:x-wiley:00084034:media:cjce24226:cjce24226-math-0002= 0.28 ± 0.02) that differ from those in bulk (urn:x-wiley:00084034:media:cjce24226:cjce24226-math-0003 = 3.14 ± 0.44, urn:x-wiley:00084034:media:cjce24226:cjce24226-math-0004= 0.27 ± 0.04). MeOH as solvent slightly reduces the propagation rate coefficient urn:x-wiley:00084034:media:cjce24226:cjce24226-math-0005 of HEMA compared to the bulk system, in contrast to the increase in the MEA urn:x-wiley:00084034:media:cjce24226:cjce24226-math-0006 value. Thus, the value of urn:x-wiley:00084034:media:cjce24226:cjce24226-math-0007 is higher in MeOH for MEA-rich systems compared to bulk, with the effect of the solvent reduced as the HEMA content in the comonomer mixture is increased. Adding water as cosolvent significantly increases urn:x-wiley:00084034:media:cjce24226:cjce24226-math-0008 values for both monomers, with urn:x-wiley:00084034:media:cjce24226:cjce24226-math-0009 in MeOH/H2O higher than bulk values over the complete composition range. Furthermore, urn:x-wiley:00084034:media:cjce24226:cjce24226-math-0010 for 50% monomer in the solvent systems studied can be represented by the implicit penultimate unit model using a single pair of radical reactivity ratios. It is concluded that the strongest influence of hydrogen-bonding solvents compared to bulk is on the homopropagation urn:x-wiley:00084034:media:cjce24226:cjce24226-math-0011 values, rather than on copolymerization parameters, and that the difference in relative reactivity of non-functional and functional monomers in bulk and aqueous solution should be accounted for when studying emulsion copolymerization.
更新日期:2021-06-16
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