Download or read book Structure Control of Functional Mesoporous Materials and Synthesis of Polydimethylsiloxane-containing Block Copolymer written by Siyang Wang and published by . This book was released on 2016 with total page 108 pages. Available in PDF, EPUB and Kindle. Book excerpt: Block copolymer templating is a versatile approach for the generation of well-defined porosity in a wide variety of framework chemistries. Here, we systematically investigate how the composition of a poly(methoxy poly[ethylene glycol] methacrylate)-block-poly(butyl acrylate) (PMPEG-PBA) template impacts the pore characteristics of mesoporous cobalt oxide films. Three templates with a constant PMPEG segment length and three different hydrophilic block volume fractions of 17%, 51% and, 68% for the PMPEG-PBA are cooperatively assembled with cobalt nitrate hexahydrate and citric acid. Irrespective of template composition, a spherical nanostructure is templated and elliptical mesostructures are obtained on calcination due to uniaxial contraction of the film. The average pore size increases from 11.4 ± 2.8 nm to 48.5 ± 4.3 nm as the length of the PBA segment increases as determined from AFM. For all three templates examined, a maximum in porosity (~35 % in all cases) and surface area is obtained when the precursor solids contain 35-45 wt % PMPEG-PBA. This invariance suggests that the total polymer content drives the structure through interfacial assembly. The composition for maximizing porosity and surface area with the micelle templating approach results from a general decrease in porosity with increasing cobalt nitrate hexahydrate content and the increasing mechanical integrity of the framework to resist collapse during template removal / crystallization as the cobalt nitrate hexahydrate content increases. Unlike typical evaporation induced self-assembly with sol gel chemistry, the hydrophilic/hydrophobic composition of the block copolymer template is not a critical component to the mesostructure developed with micelle-templating using metal nitrate-citric acid as the precursor.A series of PS-PDMS with narrow molecular weight distributions with aimed molecular weight was synthesized with PDMS-RAFT as a macro-chain transfer agent via reversible addition fragmentation chain transfer (RAFT) polymerization. The PDMS-RAFT agent is utilized to control the free radical polymerization of styrene monomer. Hydroxyl terminated polydimethylsiloxane (PDMS-OH) is end functionalized through esterification with a carboxylic acid functional RAFT agent. The thin films of the synthesized PS-PDMS block copolymers are fabricated with spin coating and subsequently annealed with solvent vapor annealing with soft shear (SVA-SS). Varied surface morphology can be obtained with different volume fraction of polystyrene block in PS-PDMS, however, long range ordered structures have not been obtained as expected. Moreover, tri-block copolymer polydimethylsiloxane-block-poly ethyl acrylate-block-poly styrene (PDMS-PS-PEA) with low polydispersity has been successful synthesized with low polydispersity (PDI) in order to investigate more interesting morphologies.