chapter  6
27 Pages

Poly(N-Isopropylacrylamide)- Based Particles

I. INTRODUCTION Within the last decades, precipitation polymerization leading to the preparation of thermally sensitive materials (i.e., polymers, gels, and microgel latex particles) has been reported and discussed as evidenced by the numerous reported papers. The first polymerization leading to linear thermally sensitive polymers has been investigated by Heskins et al. [1] using N-isopropylacrylamide (NIPAM). The obtained linear homopolymer exhibits a low critical solution temperature (LCST) at 32°C corresponding to dramatic change in the solubility parameters of the corresponding polymer. In fact, below the LCST the polymer is totally soluble in the aqueous medium, whereas above the LCST the solution exhibits phase separation induced by the polymer precipitation. The LCST of poly(NIPAM)-based polymers has been largely studied using different physical methods and approaches, such as fluorescence, turbidity, dynamic light scattering, viscosity, and calorimetric measurements.