This dissertation investigates the self assembly and automatic oscillation of intelligent poly (N-isopropylacrylamide) [PNIPAM] microgel particles. The equilibrium phase diagram as a function of temperature and concentration was constructed for the charged PNIPAM spheres. The PNIPAM microgel particles display rhythmic size oscillations when covalently coupled to a nonlinear chemical reaction, the Belousov-Zhabotinsky (BZ) reaction. The nonequilibrium dynamics of PNIPAM microgels in the presence of BZ reaction was studied by the systematic variation of substrate concentrations and temperature. In addition, the BZ chemical reaction was modeled to reveal the existence of upper temperature limits for nonlinear chemical systems. The experiments employ environment sensitive PNIPAM particles that are sensitive to temperature, pH, and ionic strength. The PNIPAM particles have been demonstrated here to behave as hard spheres at low pH values and soft spheres at high pH. This is done by measuring the freezing and melting boundary of fluid-crystal coexistence region with a new technique which is simpler and quicker compared to the traditional sedimentation method. A novel method was developed to achieve size uniformity of PNIPAM gel particles with covalently-bound tris(bipyridyl)ruthenium(II) via the coordination chemistry between a ruthenium complex and the monodispersed PNIPAM gel particles bearing bipyridine ligands. The correlation between the dynamic behavior of BZ reaction induced mechanical oscillations of PNIPAM particles and substrate concentrations was presented in a ternary phase diagram. In particular, the dependence of oscillation frequency and induction time on the substrate concentrations was studied. The temperature dependency of the induction time and oscillatory frequency of the BZ reaction in this polymerimmobilized catalyst system were compared to the bulk BZ reaction with the catalyst in the solution phase. Prolonged induction times were observed for the immobilized catalyst, compared with free catalyst, while little difference was observed on the oscillation frequency. A theoretical improvement has been achieved by incorporating the temperature dependence in the BZ Oregonator model. Bifurcation has been calculated in the phase space spanned by initial reagents concentration ratio, stoichiometric factor and temperature. The existence of upper temperature limits has been demonstrated.

Self-oscillating reactions have been widely observed and studied since the last century because they exhibit unique behaviors different from the traditional chemical reactions. Self-oscillating systems, such as the Belousov-Zhabotinsky (BZ) reaction, oxidation reaction of CO on single crystal Pt, and calcium waves in the heart tissue, are of great interest in a variety of scientific areas. This thesis contributes to the understanding of wave transition in BZ reaction, and to possible applications of non-equilibrium behaviors of polymer systems. In BZ reaction, two types of wave patterns, target and spiral, are frequently observed. The transition from one to another is not fully understood. Hence, a systematic investigation has been performed here to investigate the mechanism by which heterogeneity affects the formation of wave patterns. A BZ reaction catalyst was immobilized in ion exchange polystyrene beads to form active beads. Then active and inactive beads with no catalyst loading were mixed together with various ratios to achieve various levels of heterogeneity. In the same reaction environment, different wave patterns were displayed for the bead mixtures. We observed a transition from target patterns to spiral patterns as the percentage of the active beads in the beads mixture decreased. The increase of the heterogeneity led to wave pattern transition. Heterogeneity hindered the propagation of target waves and broke them into wavelets that generated spiral waves. In an effort to develop practical applications based on non-equilibrium phenomena, we have established a novel drug delivery system. A proton generator Zirconium Phosphate (ZrP) was imbedded inside a pH sensitive polymer matrix, poly acrylic acid (PAA). Through the ion exchange with sodium cation (Na+), ZrP generates protons to control the swelling/shrinking behaviors of PAA. The drug encapsulated in the matrix can be released in a controlled manner by adjusting the supply of Na+. This system might be developed into vehicles to deliver drugs to specific targets and release at a proper time. This new delivery technique will be convenient and significantly increase the efficiency of medicines.