两亲性聚氨酯水分散体系超分子自组装及特性的研究

According to the development of the ultramolecular self-assembly of amphiphilic polymers and the polyelectrolyte complexes in the polymer science foreground, this project took the amphiphilic polyurethane(APU) whose molecular structure was shown in Fig.1 as model polymer to study its macromolecule self-assembling behavior in acid or base aqueous solutions, the isoelectric points and the properties of APU nanomicellar dispersions. The effects of the structure such as the molecular weight, the ratio of acid groups to basic groups and the density of the ionizable groups on the self-assembly of APU were studied. The dependence of APU waterborne dispersions on the pH value of the medium, the concentration of the electrolyte and the temperature were discussed. This project also studied the physical chemistry factors presenting in the assembling process of APU with other polyelectrolyte and the properties of the complexes. .Fig.1 The molecular structure of APU.The studing results indicate that APU can self-assemble into micelles and presents characters of amphiphilic block copolymers and amphoteric polyelectroletes. The important results obtainted in this project are listed below.(1)The pH dependence of the properties of APU aqueous dispersions can be characterized by two static balance states, a dynamic equilibrium state and two turbulent states with changing the pH of the medium when the contents of the acid and base groups on APU chains are similar.(2)The pH values at isoelectric points(pHIEP) accord with the theoretical isoelectric point quations found by Patrickios and Merle by taking pKa=6.1 and pKb=8.3, even though, as an ionomer, APU has low density of ionizable groups on the macromolecular chains and take micellar state in aqueous media..(3)Special rheological properties of APU waterborne dispersions were observed. The "W" shape curves of viscosity of APU waterborne dispersions versus pH were observed both in acid and in basic mediums.(4)The APU self-assembly behavior presents largely dependence on the temperature.Because of the special molecular structure of APU and the several kinds of intramolecular interaction(including hydrogen bonding, ionic bonding and hydrophobic/hydrophilic interactions) between APU molecules, the physical chemistry questions presenting in APU ultramolecular self-assembling process are comprehensive and representative. Therefore, the studying results about the self-assembly system of APU would provide theoretic guide to the new functional polymer self-assembly materials, and provide experimental basis to the development of the meso-cosmic colloid dispersion theory, and also provide suitable models to the disclosing of the assembly and function of the organism..In addition, three new kinds of other amphiphilic copolymers, ie. poly(ethylene glycol)-poly(lactic acid) diblock copolymer, poly(ethylene glycol)-grafted-polycyanoacrylate and APU-grafted chitosan were prepared, which all can self-assemble into micelles in aqueous media. These copolymers provide new model compounds to the studying of self-assembly systems and also provede new carriers for nano drug formations.

研究各种物理化学因素对两亲性聚氨酯水分散体系从单分子胶束、到多分子聚集体、到多组分复合物的形成、性质的影响及在有序自组装过程中的作用，包括大分子构象、分子间及微区间的相互作用和组合状态、相转变、临界状态等。该研究对高功能性高分子材料的开发具有理论上的指导意义，并可为生命大分子音质精密组装机理的揭示和模仿提供一定的信息。