Complexation of Block Copolysiloxanes with Cobalt Nanoparticles

dc.contributor.authorVadala, Michael Lawrenceen
dc.contributor.committeechairRiffle, Judy S.en
dc.contributor.committeememberShultz, Allan R.en
dc.contributor.committeememberMcGrath, James E.en
dc.contributor.departmentChemistryen
dc.date.accessioned2014-03-14T20:34:04Zen
dc.date.adate2003-05-01en
dc.date.available2014-03-14T20:34:04Zen
dc.date.issued2003-04-12en
dc.date.rdate2004-05-01en
dc.date.sdate2003-04-23en
dc.description.abstractPoly(dimethylsiloxane-b-methylvinylsiloxane) (PDMS-b-PMVS) diblock copolymers were synthesized via anionic living polymerization with controlled molecular weights and narrow molecular weight distributions. Targeted molecular weights agreed well with experimental values determined by 1H NMR, 29Si NMR, and GPC. Morphologies were investigated by DSC to analyze glass transition temperatures. Only one Tg was observed for each PDMS-b-PMVS block copolymer suggesting that the blocks were miscible in bulk. Tg's ranged from approximately -126 to -128 °C and were between the Tg's of the PDMS (-123 °C) and PMVS (-137 °C) homopolymers. The PMVS blocks were functionalized with trimethoxysilethyl or triethoxysilethyl pendent groups via hydrosilations to yield poly(dimethylsiloxane-b-[poly(methylvinyl)-co-(methyl-(2-trimethoxysilethyl)siloxane)] (PDMS-b-[PMVS-co-PMTMS]) or poly(dimethylsiloxane-b-[poly(methylvinyl)-co-(methyl-(2-triethoxysilethyl)siloxane)] (PDMS-b-[PMVS-co-PMTES]) copolymers, respectively. The PMVS blocks were either derivatized with the functional groups or half of the repeat units were functionalized. The fully hydrosilated materials were diblock copolymers, and the materials that were 50% hydrosilated had a random sequence of methylvinylsiloxy units and methyl-(trialkoxysilethyl)siloxy units. The PDMS-b-[PMVS-co-PMTES] block copolymers had Tg's ranging from -124 to -126 °C and only one Tg was observed. Surface tension measurements suggested that PDMS-b-[PMVS-co-PMTES] copolymers formed aggregates in toluene. Stable suspensions of superparamagnetic cobalt nanoparticles were prepared in toluene in the presence of PDMS-b-[PMVS-co-PMTMS] or PDMS-b-[PMVS-co-PMTES] copolymers via thermolysis of Co2(CO)8. It is hypothesized that the block copolymers functioned as micellar templates for the cobalt nanoparticles. TEM micrographs showed non-aggregated cobalt nanoparticles coated with copolymers that had mean particle diameters ranging from ≥10-15 nm. Specific saturation magnetizations of these cobalt-copolymer complexes ranged from 90-110 emu g-1 Co, comparable to literature values for this particle size.en
dc.description.degreeMaster of Scienceen
dc.identifier.otheretd-04232003-220636en
dc.identifier.sourceurlhttp://scholar.lib.vt.edu/theses/available/etd-04232003-220636/en
dc.identifier.urihttp://hdl.handle.net/10919/31841en
dc.publisherVirginia Techen
dc.relation.haspartMastersThesis.pdfen
dc.relation.haspartMastersPreface.pdfen
dc.rightsIn Copyrighten
dc.rights.urihttp://rightsstatements.org/vocab/InC/1.0/en
dc.subjectnanoparticleen
dc.subjectmagneticen
dc.subjectpolydimethylsiloxaneen
dc.subjectcobalten
dc.subjectpoly(methylvinylsiloxane)en
dc.subjectpolysiloxaneen
dc.titleComplexation of Block Copolysiloxanes with Cobalt Nanoparticlesen
dc.typeThesisen
thesis.degree.disciplineChemistryen
thesis.degree.grantorVirginia Polytechnic Institute and State Universityen
thesis.degree.levelmastersen
thesis.degree.nameMaster of Scienceen
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