ABSTRACT
In this chapter, the authors demonstrate new pH/temperature-sensitive polymers with transitions resulting from both polymer-polymer and polymer-water interactions and their applications as stimuli-responsive drug carriers. For this purpose, copolymers of (N,N-dimethylamino)ethyl methacrylate (DMAEMA) and ethylacrylamide (EAAm) were prepared and characterized as polymeric drug delivery systems modulated for pulsatile and time release. Copolymers of DMAEMA and acrylamide were prepared by free radical polymerization in water at room temperature using ammonium persulfate as initiator and tetramethylethyl-diamine as accelerator. As the solvent in a polymer solution becomes poorer, e.g., through a temperature change, a phase transition will eventually take place. There have been a number of reports on the phase transition polymers in response to various external stimuli such as pH, temperature, light, and chemical substances. Two-compartment glass permeation cells were used for solute permeation study as a function of temperature. Hydrocortisone was used as a model solute.
