Controllable association of polyelectrolytes in dilute solution

In this thesis, several systematical studies on complexation/association of linear chains and microgels of polyelectrolytes in solutions have been carried out by a combination of static and dynamic laser light scattering.;Firstly, Ca2+ concentration and hydrolysis degree [COO -] dependence of the self-complexation of partially hydrolyzed poly(acrylamide) (HPAM) chains in CaCl2 aqueous solution was investigated. We have, for the first time, revealed a transition between the intrachain and interchain complexations.;Spherical microgels and linear chains were prepared by precipitation copolymerization of N-vinylcaprolactam and sodium acrylate [P(VCL-co-NaA)] in water. The copolymerization of a few molar percent of NaA into a PVCL chain increases its swelling extent and shifts its shrinking temperature slightly higher.;The time evolution of both Mw and the average hydrodynamic radius () of the aggregates was simultaneously recorded. It showed that for microgel aggregates, Mw could be scaled to as Mw ∝ df and the average scattering intensity I(q) varied with the scattered vector q as I(q) ∝ q -dq with df and dq in the range 1.6--1.9, indicating that the aggregation of microgels is a diffusion limited process.;The aggregation induced by different kinds of cations was also investigated. At temperatures lower than ∼30°C, the microgel shrinks as the cation concentration increases due to the increase of the ionic strength and the intra-microgel complexation. The extent of the shrinking induced by different cations follows the order of Hg2+ >> Cu2+ > Ca2+ > Na+.;The temperature dependence of the complexation between microgels and linear gelatin chains was studied. Without Ca2+, the complexation is weak. With Ca2+, the complexation occurred at ∼32°C is much stronger and independent of the gelatin/microgel ratios ([G]/[M]), but both average aggregation number Nagg and average chain density decrease as [G]/[M] increases because the adsorption of too many hydrophilic gelatin chains on the microgels hinders the complexation and reduces the shrinking of the complexes.;We conducted a series of in-vivo animal tests. 193 rats and 39 guinea pigs have been used. The hybrid hydrogels were embedded and liquid mixtures were injected into different positions inside animal body. Our results showed no obvious and severely adverse effects. After 6 months, the nerve and muscle appeared normal. In the morphological measures of cell viability or death, no significant cytotoxicity was found. (Abstract shortened by UMI.).