Grafting of thermo- and pH-responsive polymer inside mesoporous silica foam in supercritical carbon dioxide for controlled release of 5-fluorouracil

Mesocellular silica foam (MCF) grafted with thermo-responsive and pH-responsive copolymer poly( N -isopropylacrylamide- co -acrylic acid), was prepared by precipitation polymerization using supercritical carbon dioxide (scCO 2 ) as entrainer and solvent. Vinyl-functionalized MCF was first synthesized through post-synthesis via using vinyltriethoxysilane as a coupling agent for surface modification. Entrapped monomers of N-isopropylacrylamide (NIPA) and acrylic acid (AA) were then introduced and assembled onto the vinyl-modified MCF with the aid of scCO 2 . The grafting copolymer performed here as an on/off switch in the release of 5-fluorouracil, as confirmed by using UV-visible absorption spectroscopy. The grafted organic content and drug loading efficiency were 65.2 wt% and 11.5 wt%, respectively. The resultant grafting composite showed potential for application in drug delivery and exhibited thermo- and pH-responsiveness to external environmental changes.