Synthesis and characterization of ionic liquid functionalized polymers for drug delivery of an anti-inflammatory drug.

Polymeric forms of ionic liquids have many potential applications because of their ionic nature. Two ionic liquid monomers, 1-(4-vinylbenzyl)-3-methyl imidazolium hexafluorophosphate (VMIH) and 1-(4-vinylbenzyl)-4-(dimethylamino)-pyridinium hexafluorophosphate (VDPH), were synthesized through the quaternization of N-methylimidazole and 4-(dimethylamino) pyridine with 4-vinylbenzylchloride, respectively, and a subsequent anion exchange reaction with potassium hexafluorophosphate. The homopolymers of VMIH, VDPH, and its copolymers with methyl styrene (in various mole ratios) were synthesized by free radical polymerizations at 70 °C using α,α'-azobis(isobutyronitrile) as an initiator. Anionic drug molecule, naproxen (an anti-inflammatory drug), was effectively loaded into these positive charges polymers (PCP) and remained inside of the PCP under acidic environment (pH 2-6.5). The amount of loading of drug was increased with increasing positive charge densities resulting from the increasing number of ionic liquids groups. PCP as a controllable release of anionic drug molecules can be used as an oral delivery drug systems targeting at intestine. This drug can be remained trapped in the polymers when passing through the acidic and neutral environment and be released in intestine, where the environmental pH is close to basic.