Layer-by-Layer Fabrication Of Multilayer Films Of Polyelectrolyte Complexes

In the past decade, the layer-by-layer (LbL) assembly technique has attracted extensive attentions of chemists, due to its valuable characteristics in composite film fabrication, such as independence of the geometry of the substrates capable of film deposition, abundance in materials used for LbL film fabrication, easiness in fine tailoring film composition and structures, and so forth. Advanced multilayer film materials with components such as polyelectrolytes, organic/inorganic particles , biomacromolecules such as proteins,enzymes,virus, oligocharged organic compounds and dentritic molecules have been successfully fabricated by the LbL assembly technique. Extension of materials for LbL film fabrication will certainly enrich the structures and therefore functionalities of the LbL assembled film materials. In recent decades, polymeric complexes have been under intense investigation for various potential applications, benefiting from their versatility in chemical composition and structures. The driving force for polymeric complexes formation is mainly electrostatic interactions, hydrogen bonding, coordination bond , guest–hostinteraction and the synergetic interaction of the above forces, etc. Polymeric complexes possess versatile structures in solution which are believed to be helpful to obtain polymeric films with well-tailored structures as well as functionalities. However, less attention has been paid to use polymeric complexes for LbL assembled multilayer fabrication. In this dissertation, we demonstrated that highly aggregated polymeric complexes can be used as building blocks for LbL film fabrication. The structures as well as the functionalities of the resultant LbL assembled films were fully tailored and explored.In charpter 2, noncharged pyrene molecules were incorporated into multilayer films by first loading pyrene into poly(acrylic acid) (PAA)-stabilized cetyltrimethylammonium bromide (CTAB) micelles (noted as PAA&(Py@CTAB)) and then layerby-layer (LbL) assembled with poly(diallyldimethylammonium chloride) (PDDA). The stable incorporation of pyreneinto multilayer films was confirmed by quartz crystal microbalance (QCM) measurements and UV-vis absorptionspectroscopy. The resultant PAA&(Py@CTAB)/PDDA multilayer films show an exponential growth behavior because of the increased surface roughness with increasing number of film deposition cycles. The present study will open a general and cost-effective avenue for the incorporation of noncharged species, such as organic molecules, nanoparticles, and so forth, into LbL-assembled multilayer films by using polyelectrolyte-stabilized surfactant micelles as carriers.In charpter 3, positively charged poly(allylamine hydrochloride) (PAH) and poly (acrylic acid) (PAA) complexes (noted as PAH-PAA) with a molar excess of PAH were layer-by-layer (LbL) assembled with polyanion poly(sodium-4-styrenesulfonate) (PSS) to produce multilayer films. The thermally cross-linked PAH-PAA/PSS films can be released from substrate to form stable free-standing films by an ion-triggered exfoliation method.Meanwhile, positively charged PAH-PAA complexes can be LbL assembled with negatively charged PAH-PAA complexes with a molar excess of PAA to produce multilayer films. Use of polyelectrolyte-polyelectrolyte complexes as building blocks for LbL fabrication provides a facile way to tailor the structures of the resultant films by simply changing the structure of the complexes in solution.