Investigation of the mercat reaction as a tool for the introduction of nitrogen surface functionality on linear low-density polyethylene (LLDPE) and polypropylene (PP)

Mercury photosensitized chemical reaction in the presence of aqueous ammonia (NH4OH) is found to be a simple and versatile method of introducing polar surface functionalities comprising nitrogen and oxygen on polyolefins such as low-density polyethylene (LLDPE) and polypropylene (PP). Thus, nitrogen and oxygen surface functionalities are introduced in a surface selective manner on LLDPE and PP to give a relatively hydrophilic surface as revealed by XPS, ATR-IR, and water contact angle analyses. XPS, water contact angle, ATR-IR, and SEM are used to characterize the modified surfaces. Preliminary investigations also reveal that surface selective functionalization of a wide variety of polymers such as PET, Teflon-AF, PTFE, and fluoroethylene-propylene copolymer (FEP) can be performed by this simple method of surface modification. Thus, it is observed that crystallinity and segmental mobility as exemplified by glass transition temperature could be important factors in polymer surface modification besides inherent reactivity based on chemical structure alone. A model of the modified surface consistent with the surface characterization data is proposed.