Synthesis and Applications of Inorganic/Organic-PolymerNanocomposites

[摘要] This research work focuses on developing new synthesis routes to fabricatepolymer nanocomposites tailored towards different applications. A simple, one-stepmethod has been devised for synthesizing free-standing, flexible metal nanoparticlepolydimethylsiloxanefilms. This process simplifies prevalent methods to synthesizenanocomposites, in that here nanoparticles are created in situ while curing the polymer.This route circumvents the need for pre-synthesized nanoparticles, external reducingagents and stabilizers, thereby significantly reducing processing time and cost. Theresulting nanocomposite also demonstrates enhancement in mechanical and antibacterialproperties, with other envisaged applications in biomedical devices and catalysis.Applying the same mechanism as that used for the formation of bulk metalsiloxanenanocomposites, metal core-siloxane shell nanoparticles and siloxane nanowireswere synthesized, with octadecylsilane as the precursor and in situ formed metalnanoparticles (gold, silver) as the catalyst. This method offers some unique advantagesover the previously existing methods. This is a room temperature route which does notrequire high temperature refluxing or the use of pre-synthesized nanoparticles.Furthermore, this synthesis process gives a control over the shape of resultingnanocomposite structures (1-D wires or 0-D spherical particles).High thermal stability of polydimethylsiloxane (PDMS) makes it viable toalternatively synthesize metal nanoparticles in the polymer matrix by thermaldecomposition process. This technique is generic across a range of metals (palladium,iron, nickel) and results in nanoparticles with a very narrow size distribution. Membranes111with palladium nanopartic1es demonstrate catalytic activity in ethylene hydrogenationreaction.Additionally, a new nanocomposite electrode has been developed for flexible andlight-weight Li-ion batteries. Flexible films were prepared by the integration of thepoly(vinylidene fluoride-hexafluoropropylene (PVDF-HFP) polymer electrolyte with thethree-dimensional (3D), nanostructured electrode composed of aligned carbon nanotube(CNT)-copper oxide hybrid. This hybrid electrode was fabricated by a combination ofchemical vapor deposition and electrodeposition techniques. Embedding it in PVDFpolymer results in a flexible system and also renders an external separator redundant.This new design shows an improvement in electrochemical performance over pure CNTsas both CNTs and CU20 contribute towards electrochemical activity.Efforts have also been undertaken towards synthesizing synthetic adhesives bymimicking the design principles found in nature. Aligned patterned CNTs have been usedto replicate the fibrillar structure found in geckos' toes which generates adhesion throughvan der Waals forces. The adhesive forces in CNTs were found to be higher than ingeckos and the key to this phenomenon lies in the extensive side-wall contact obtained oncompressing CNTs against a surface.

[发布机构] Rice University

[效力级别] Mathematics