Humidity sensitive properties of restructural films prepared from polymer latex with carboxylic acid functional groups

The polymer latex of poly(butyl acrylate(BA)-aclylic acid(AA)) was synthesi zed by soapless seeded emulsion polymerization or soapless emulsion copolym erization. The morphology of the composite polymer latex synthesized by soa pless seeded emulsion polymerization was core-shell structure. The humidity -sensitive polymer films were made by the melting of the polymer latex at 6 8 degrees C followed by chemical modification with aqueous solution of NaOH . The glass transition temperature (T-g) of poly(butyl acrylate) (PBA) is b elow room temperature(- 54 degrees C), so PEA has flexible behavior at the room temperature. The humidity-sensitive properties of the flexible polymer films were investigated. The core-shell polymer latex with either linear c ore or crosslinked core was synthesized. The polymer latex that had the cro sslinked core was melted to form polymer films with crosslinked domains. Th e polymer latex that had the linear core was melted to form the polymer fil ms with linear structure. It is confirmed that polymer films with crosslink ed domains had larger humidity sensitivity and less hysteresis than polymer films with linear structure. The effect of multiple use on the humidity se nsitivity of the polymer films with crosslinked domains was insignificant. For polymer films with crosslinked structure or poor flexibility, the degre e of humidity sensitivity increased with temperature. The humidity sensitiv ity may decrease with increase of temperature for flexible films.