Poly(methacrylic acid)‐l‐Polyisobutylene Amphiphilic Conetworks by Using an Ethoxyethyl‐Protected Comonomer: Synthesis, Protecting Group Removal in the Cross‐Linked State, and Characterization

Abstract

A series of poly(methacrylic acid)‐l‐polyisobutylene anionic amphiphilic conetworks with hydrophobic polyisobutylene (PIB) content between 33% and 70% (w/w) is synthesized by the macromonomer method using a new approach by applying ethoxyethyl‐protected methacrylic acid (EEMA) comonomer. To remove the protecting group after copolymerization of EEMA with PIB‐dimethacrylate, acidic hydrolysis and thermal treatment are attempted, and the success of the deprotection is monitored by different techniques. Comparing the two protective group removal steps, it is found that, in contrast to homopolymers of EEMA, the acidic hydrolysis is more favorable than the thermal deprotection due to anhydride formation during the latter process in the conetworks. Distinct glass transitions are obtained by differential scanning calorimetry (DSC) indicating phase separation in the resulting conetworks. The swelling ability of the obtained conetworks in polar and nonpolar solvents proves the amphiphilic nature of these materials. Due to the polyacidic component of the conetworks, their water swollen gels have pH‐sensitive, intelligent swelling behavior in aqueous media. Because of the relatively high stability of EEMA, the applied protection–deprotection strategy can be easily utilized in several other designed polymer syntheses. image