Analysis of Acrylic Copolymers Containing Carboxyl Groups by the Derivatization Technique and DOSY

Copolymers and quaterpolymers containing acrylic acid as a comonomer were analyzed by H-1 Diffusion-ordered NMR spectroscopy (H-1 DOSY) to determine their molecular-weight dependencies of chemical composition. The carboxylic acid moieties in those copolymers were derivatized to trimethylsilyl groups to measure the distribution of the diffusion coefficient for the acrylic acid units in satisfactory sensitivity. The DOSY analysis was carried out successfully by introducing an excess amount of N,O-bis(trimethylsily)trifluoroacetamide directly to the solution in a sample tube. This method was applied to the study of the relationship between molecular-weight dependence of chemical composition and copolymerization procedures (comonomer feed procedures) for three quaterpolymer samples comprising methyl methacrylate, butyl acrylate, styrene and acrylic acid.