| dc.description.abstract | Interest in producing hybrid organic-inorganic (HOI) materials has increased rapidly due to the unique combination of properties from the organic and inorganic components. The goal of the research described is to develop various HOI materials and explore their applications in corrosion protection over aerospace aluminum alloys, impact resistant materials, and surface protection over thermoplastic substrates.
As a replacement to toxic chromate inhibitors, enrivonmentally friendly magnesium-rich primers (Mg-rich primers) have been investigated to provide corrosion protection over aerospace aluminum alloys. HOI binders were produced from an alkoxy silane and silica via sol-gel chemistry, where the combined organic and inorganic components provide flexibility, adhesion, and barrier properties. The derived topcoated Mg-rich primers showed promising corrosion protection in a salt spray exposure test and are competitive with chromate-containing primers. The condensation catalyst, tetrabutyl ammonium fluoride (TBAF), played an important role in the performance of the HOI binders and the derived Mg-rich primers. It enabled higher crosslink density and better barrier properties, however, reacted with Mg particles during salt spray exposure and caused the formation of blisters. A non-ionic condensation catalyst, dibutyltin dilaurate (DBTDL), had lower catalyst strength, but was expected to eliminate the blister formation of topcoated Mg-rich primers.
Perfectly alternating polycarbonate-polydimethylsiloxane (PC-PDMS) multiblock copolymers were produced to create transparent impact resistant materials by confining the size of the rubber domains. The PC-PDMS block copolymers maintained high transparency at up to 62 wt% PDMS and shorter block length gave rise to larger partial miscibility. By incorporating the PDMS blocks to dissipate energy, the PC-PDMS block copolymers had much better impact strength than pure PC oligomers.
Thermoset polycarbonate-polyhedral oligomeric silsesquioxane (PC-POSS) coatings were investigated to serve as surface coatings on PC substrate to provide abrasion resistance. The covalent bonding allowed high POSS loading at up to 18 wt% without sacrificing the transparency. The solvent composition and curing conditions largely determined the surface and bulk properties of the coatings. The incorporation of POSS molecules significantly increased the char yield and mechanical strength of the thermoset coatings, making them promising in surface protection applications. | en_US |
