Degree of polymerization in two-dimensional assemblies of acryloyl or methacryloyl lipids.

Persistent Link:
http://hdl.handle.net/10150/185376
Title:
Degree of polymerization in two-dimensional assemblies of acryloyl or methacryloyl lipids.
Author:
Sells, Todd Douglas.
Issue Date:
1991
Publisher:
The University of Arizona.
Rights:
Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
Abstract:
The first systematic study of the effect of variations in initiator and monomer concentrations on two-dimensional polymerizations is described here. The number average degree of polymerization, X(n), was estimated by SEC for the thermal polymerization of bilayers composed of a mono-substituted acryloyl phospholipid. When the monomer to initiator (azobisiso-butyronitrile) molar ratio, [M]/[I], was varied from 5 to 40, holding [M] constant, the X(n) increased from 233 to 1,936. The measured X(n) was observed to be inversely proportional to the initiator concentration. When the monomer concentration was diluted by the incorporation of a nonpolymerizable lipid (DMPC), the X(n) was decreased from 1,476 for pure mono-acryloyl PC to 299 for a 1/1 molar ratio of mono-acryloyl PC and DMPC. The X(n) was found to be dependent on the square of the monomer mole fraction in the bilayers. The polymerization of bis-acryloyl PC produced much shorter polymers than mono-acryloyl PC but appeared to have the same dependency on initiator concentration. These data suggest that this two-dimensional polymerization is preferentially terminated by reaction with initiator fragments rather than by the usual radical coupling and/or disproportionation reactions of the growing polymer chains. It is suggested that the preference for termination by small molecular fragments is a consequence of limited diffusion of the growing polymer chains in the constrained environment of the lipid bilayer. Furthermore these data demonstrate that careful attention to the ratio of [M]/[I] is necessary to reproducibly control the size and properties of polymers formed in supramolecular assemblies.
Type:
text; Dissertation-Reproduction (electronic)
Keywords:
Dissertations, Academic; Chemistry, Organic
Degree Name:
Ph.D.
Degree Level:
doctoral
Degree Program:
Chemistry; Graduate College
Degree Grantor:
University of Arizona
Advisor:
O'Brien, David

Full metadata record

DC FieldValue Language
dc.language.isoenen_US
dc.titleDegree of polymerization in two-dimensional assemblies of acryloyl or methacryloyl lipids.en_US
dc.creatorSells, Todd Douglas.en_US
dc.contributor.authorSells, Todd Douglas.en_US
dc.date.issued1991en_US
dc.publisherThe University of Arizona.en_US
dc.rightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.en_US
dc.description.abstractThe first systematic study of the effect of variations in initiator and monomer concentrations on two-dimensional polymerizations is described here. The number average degree of polymerization, X(n), was estimated by SEC for the thermal polymerization of bilayers composed of a mono-substituted acryloyl phospholipid. When the monomer to initiator (azobisiso-butyronitrile) molar ratio, [M]/[I], was varied from 5 to 40, holding [M] constant, the X(n) increased from 233 to 1,936. The measured X(n) was observed to be inversely proportional to the initiator concentration. When the monomer concentration was diluted by the incorporation of a nonpolymerizable lipid (DMPC), the X(n) was decreased from 1,476 for pure mono-acryloyl PC to 299 for a 1/1 molar ratio of mono-acryloyl PC and DMPC. The X(n) was found to be dependent on the square of the monomer mole fraction in the bilayers. The polymerization of bis-acryloyl PC produced much shorter polymers than mono-acryloyl PC but appeared to have the same dependency on initiator concentration. These data suggest that this two-dimensional polymerization is preferentially terminated by reaction with initiator fragments rather than by the usual radical coupling and/or disproportionation reactions of the growing polymer chains. It is suggested that the preference for termination by small molecular fragments is a consequence of limited diffusion of the growing polymer chains in the constrained environment of the lipid bilayer. Furthermore these data demonstrate that careful attention to the ratio of [M]/[I] is necessary to reproducibly control the size and properties of polymers formed in supramolecular assemblies.en_US
dc.typetexten_US
dc.typeDissertation-Reproduction (electronic)en_US
dc.subjectDissertations, Academicen_US
dc.subjectChemistry, Organicen_US
thesis.degree.namePh.D.en_US
thesis.degree.leveldoctoralen_US
thesis.degree.disciplineChemistryen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.grantorUniversity of Arizonaen_US
dc.contributor.advisorO'Brien, Daviden_US
dc.contributor.committeememberMulvaney, Jimen_US
dc.contributor.committeememberBates, Roberten_US
dc.contributor.committeememberWigely, Daviden_US
dc.contributor.committeememberBurke, Michaelen_US
dc.identifier.proquest9123150en_US
dc.identifier.oclc709625887en_US
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