Polymethacrylic acid Derivatives, 1. Preparation, Characterization, and Potentiometric study of poly(N‐methacryloyl‐L‐alanine‐co‐N‐phenylmethacrylamide)

Poly( N ‐methacryloyl‐L‐alanine) and poly( N ‐methacryloyl‐L‐alanine‐co‐ N ‐phenylmethacrylamide) containing up to 38 mole‐% of N ‐phenylmethacrylamide were synthesized by radical copolymerization. These polymers were characterized by UV and IR spectroscopy and by conductimetric titrations. The samples were then studied by potentiometric titrations in pure water and in aqueous organic solvents, in the temperature range of 5 ‐ 65°C. The experimental results show that, opposite to poly(methacrylic acid), poly( N ‐methacryloyl‐L‐alanine) takes no compact structure in water. The insertion of N ‐phenylmethacrylamide induces the appearance of this compact structure over 15 mole‐% of this residue. Thereafter, the stability of the compact structure increases when increasing the amount of N ‐phenylmethacrylamide. Experimental results suggest that it is due to increasing Van der Waals interactions between the hydrophobic side chains.