Statistical Copolymers Comprising Bio-Based Aromatic Methacrylate Segments and Their Influence on the Glass Transition Temperature

Synthesis of statistical copolymers is described from bio-based 4-(4-methacryloyloxyphenyl)butan-2-one (1) with an aliphatic methacrylate, such as n-butyl methacrylate (2), N,N-(dimethylamino)ethyl methacrylate (3), and lauryl methacrylate (4), using mostly dimethyl sulfoxide as solvent in the free radical polymerization. Though 4 is insoluble in dimethyl sulfoxide, diethyl carbonate is the preferred solvent for the copolymerization using this monomer although both yield and molecular weight are lower even for poly(4-(4-methacryloyloxyphenyl)butan-2-one) than using dimethyl sulfoxide as solvent. H-1 NMR spectroscopic analysis gives information about the content on the monomer segments in all copolymers. Furthermore, elementary analysis additionally supports the results obtained for the copolymers made from 1 and 3. As shown by the copolymerization diagrams and the copolymerization parameters, the copolymerization of 1 with 2 is a nearly ideal copolymerization using short polymerization time (20 min). Extending the polymerization time results in slight deviation from an ideal copolymerization. Furthermore, the glass transition temperature of the copolymers determined by DSC and calculated using both the Fox equation and the Gibbs-DiMarzio equation show the strong influence of the copolymer composition. As expected, the glass transition temperature increases with increasing content on aromatic segments in the copolymer that may be interesting for application in coatings and adhesives, respectively.

Automated summary

This article describes the synthesis of statistical copolymers using bio-based 4-(4-methacryloyloxyphenyl)butan-2-one (1) and aliphatic methacrylates, such as n-butyl methacrylate (2), N,N-(dimethylamino)ethyl methacrylate (3), and lauryl methacrylate (4), with dimethyl sulfoxide as the solvent in free radical polymerization. The copolymerization of 1 with 2 shows nearly ideal behavior with short polymerization time, while deviations from ideal behavior are observed with extended polymerization time. The glass transition temperature of the copolymers is influenced by the copolymer composition, with an increase in the content of aromatic segments leading to higher glass transition temperature.