THE SYNTHESIS AND SOLUTION PROPERTIES OF STATISTICAL AND BLOCK COPOLYMERS OF 2-VINYL PYRIDINE AND ACRYLIC-ACID

Statistical and block copolymers of 2-vinyl pyridine (2VP) and acrylic acid (AA) were prepared. The solubility of the copolymers and the degree of protonation of 2VP units were investigated as functions of pH. At low pH, the copolymers were soluble but, on increasing the pH, they tended to precipitate as the isoelectric point was approached. At high pH, statistical copolymers redissolved to give molecular solutions, whereas a block copolymer formed micelles. The apparent basicity of 2VP units was significantly influenced by long-range interactions; inclusion of AA units within a 2VP chain led to an apparent increase in basicity whereas AA units in a separate block apparently decreased the basicity of the 2VP.