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pH-Responsive poly(styrene-alt-maleic anhydride) were synthesized and modified to improve their surface activity for transmembrane protein extraction. Different samples were synthesized by single-step solution polymerization using peroxy radical initiator, prior to esterification. The half esterified samples (ePSMA) became weaker polyelectrolytes with reduced acid dissociation constant (ka). In the low compression region (>23 cm2), it showed reduced surface pressures, implying weakened lateral electrostatic repulsion. It could also decrease water surface tension to 40 mN/m, beyond that of the unmodified one. The method has proved to be useful for a design of workable pH-switchable systems for a wider context of extraction technology.
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