Biocatalytic approach for polymer synthesis and polymer encapsulation in mesoporous materials.

摘要

The goal of this research is to encapsulate enzymatically synthesized polymers within the pores of mesoporous silica. In order to fully understand the effect of polymer incorporation on mesoporous silica structure, the effect of dopant and polymer on micelle shape, the effect of dopant on the final mesoporous silica structure, and the effect of incorporating polymer within mesoporous silica are investigated.; Direct entrapment of aromatic molecules within cationic micelles to ultimately fabricate tailored, functional mesoporous silica/polymer composites is investigated. Specifically, the influence of 4-ethylphenol and aniline on the shape of cetyltrimethylammonium bromide (CTAB) micelles and on the structure of mesoporous silica synthesized via the micellar templating is investigated. Small angle neutron scattering indicates that the dopant affects the micellar size, micellar arrangement, and the domain size over which the arrangement extends. Cryo-TEM offers further insight into the micellar shape. The effect of the dopant-to-surfactant molar ratio on the structure of surfactant-templated mesoporous silica is characterized by x-ray diffraction, transmission electron microscopy, and nitrogen sorption techniques. The mesoporous silica undergoes a transition from hexagonal to lamellar with increasing dopant-to-surfactant molar ratio for both 4-ethylphenol and 2-naphthol, suggesting a possible change in the template morphology. A better understanding of the relation between dopant, micellar shape, and mesoporous structure plays a critical role in the development of polymer-ceramic nanocomposites with novel electrooptical, conductive, and fluorescent properties.; A novel method for encapsulating polymers in mesoporous silica is presented. The method involves enzymatic synthesis of polyphenols and polyaromatic amines in micellar aggregates, and subsequently condensing silica at the surfactant-water interface. Thus, poly(4-ethylphenol), poly(2-naphthol), and polyaniline are synthesized via peroxidase catalyzed polymerization in cetyltrimethylammonium bromide (CTAB) micelles. X-ray diffraction and transmission electron microscopy indicate that the polymer/silica mesophase undergoes a transition from hexagonal to lamellar with increasing monomer-to-surfactant ratio. Nitrogen sorption isotherms confirm mesoporosity of the mesoporous silica/polymer composites. The fabrication of polymer entrapped in ordered, nanometer-sized channels represents an important step toward the development of polymer-ceramic nanocomposites with potential applications in thin films for sensor applications.