The development of novel smart wound dressings based on colloidal microgels and cotton fabric

A series of microgels have been prepared by a surfactant free emulsion polymerisation based on an N-isopropylacrylamide (NIPAM) monomer. Poly(NIPAM) is a thermo sensitive polymer which undergoes a conformational transition close to the human skin temperature. Poly(NIPAM) was co-polymerized with hydrophobic butyl acrylate (BA) to provide a more favourable environment for drug molecules to partition into within the particle. A second co-monomer, acrylic acid (AA) was used to prepare pH/temperature sensitive microgels. The coupling reactions between microgels and cotton cellulose are only feasible if they both have appropriate functionalities. For microgels, this was achieved by using different initiators which introduce different functional groups on the particle surfaces and different surface changes. Cotton samples were successfully modified by carboxymethylation, periodate oxidation, grafting of 1,2,3,4-butanetetracarboxylic acid, and chloroacetylation in order to target possible reactions with the terminal functional groups of the microgel particles. Microgels were attached to the cotton fabrics using different methods. The maximum weight increase of cotton samples due to the attached microgels was 23.51 ± 0.29% (w/w). Drug loading and drug release were studied for free (unattached) microgels and novel wound dressings. Methyl paraben (MP) was used as a model drug compound. The results of MP release from free microgels show no significant influence of surface charge on MP release. However, BA-containing microgel particles release less MP than 100% poly(NIPAM) microgels due to hydrophobic interactions between the MP and the BA. Temperature-sensitive dressings release up to 45% more MP at 40°C than at 30°C. The drug release for pH-sensitive dressings was up to 24% higher at pH 5 than at pH 8. This demonstrates that the novel dressings can be classed as “smart” materials as they can respond to subtle changes in simulated wound fluid temperature and pH.EThOS - Electronic Theses Online ServiceGBUnited Kingdo