Abstract
This thesis is centered on the self-assembly behavior of nanostructured poly(vinyl alcohol) (PVA) constructed by block copolymer and polymer-surfactant complex. It is further divided into two parts. The first part discusses the self-assembly behavior of PAA-b-PVA block copolymer and PAA/PVA blends. The tensile properties of the block copolymer films were in general much better than those of the corresponding blend, where the maximum fractural tensile stress and strain attained were 27.3 MPa and 641 %. The FTIR study indicated that the extent of hydrogen bonding between PAA and PVA transferred from the solution state could explain the variation of the mechanical properties of a given type of films prepared from the solutions with different pH values, but it was unable to rationalize the large difference between the block copolymer and the blend films prepared under a given pH environment. Combining the results of FTIR spectra, DSC, solution turbidity and SAXS, we proposed that the films composed of the interpolymer complex domains distributed over a matrix phase in which PVA and PAA were phase separated. In the blend films, the phase separation occurred at the macroscopic length scale, generating the PAA and PVA domains of micrometers in size. On the other hand, PVA and PAA blocks in the block copolymer underwent the microphase separation, generating a characteristic nanostructure as evidenced by the SAXS profile. The nanostructure thus formed may prescribe a large amount of interface that led to the considerable enhancement of the tensile properties. In the second part, we studied the self-assembly behavior and phase behavior of polyvinyl alcohol (PVA)/amphiphilic dodecylbenzenesulfonic acid (DBSA) complexes formed by hydrogen bonds. A supramolecular comblike polymer system has been successfully prepared by the complexation of PVA with DBSA via hydrogen bonding. Microphase separation between the polar and nonpolar units generated a lamellar mesophase, as revealed by POM and SAXS. The interlamellar distance increased with decreasing binding fraction of DBSA, indicating that DBSA bound uniformly with PVA backbone. The TODT was found to be largely independent of the binding ratio, which might be due to the occurrence of chemical degradation at elevated temperature.