Polymer nanorods: Preparation, analysis, and chemical modification
Abstract (Summary)The overall objectives of the projects which constitute this Ph.D. thesis are a preparation of two-component polymer nanorods using anodic alumina membranes as templates and an investigation of their structures as well as a possibility for a preparation of composite nanorods. Anodic alumina membranes with various pore size prepared by the anodization of aluminum in electrochemical cell are used as well as commercial membrane (Chapter 2). Diblock copolymer nanorods are prepared using these membranes and their microphase-separated structures inside the membrane pores are investigated (Chapter 3 and 4). Semicrystalline polymer nanorods are prepared using these membranes and their composites are prepared by polymerizing second monomer inside these nanorods (polymer/polymer composite nanorods) or depositing metal clusters inside these nanorods (polymer/metal composite nanorods) (Chapter 5). Microphase-separated structures of diblock copolymers inside the cylindrical membrane pores are affected by the relationship between the size of pores and the repeat period of the block copolymers (commensurability). Polystyrene- b -polybutadiene (PS- b -PBD) confined inside the membrane pores show novel structures that cannot be accessed by any other method, caused by the commensurability and large curvature of the templates. The interaction between each block of diblock copolymer and the alumina surface is another factor for the micro-phase separated structures of diblock copolymers inside alumina membrane pores. Surface modification of alumina membrane pores using octyltrimethoxysilane (OTMS) inverted the multi-barrel structure of symmetric polystyrene- b -polymethylmethacrylate (PS- b -PMMA) and asymmetric PS- b -PMMA at large D/L 0 , by changing the polarity of the templates. Asymmetric PS- b -PMMA at small D/L 0 does not show this inversion. Poly(4-methyl-1-pentene) (PMP) nanorods are prepared using commercial alumina membranes. PMP/polynorbornene nanorods are prepared by polymerizing norbornene inside PMP nanorods using liquid CO 2 as reaction medium. This also provides a way to observe the structures of these semicrystalline polymer nanorods. PMP/Pt nanorods are prepared by introducing Pt precursors, dimethyl(cyclooctadiene)platinum(II) (CODPtMe 2 ), clusters using supercritical CO 2 as a medium and reducing it with H 2 to form Pt clusters inside PMP nanorods.
School Location:USA - Massachusetts
Source Type:Master's Thesis
Date of Publication:01/01/2007