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Timothy M. Swager. Song, Changsik Massachusetts Institute of Technology. Dept. of Chemistry. Massachusetts Institute of Technology. Department of Chemistry 2008-05-19T15:00:33Z 2008-05-19T15:00:33Z 2007 2007 http://hdl.handle.net/1721.1/41554 224002757 Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemistry, 2007. This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections. Includes bibliographical references. To date, the most successful conducting polymer actuators are based on polypyrrole, which operates through incorporating and expelling counterions and solvent molecules to balance the charges generated by electrochemical stimuli (swelling mechanism). Although significant progress has been made, there still exists a need for developing new materials that would overcome the intrinsic limitations in the swelling mechanism, such as slow diffusion rate, limited expansion volume, etc. Our group has contributed this area with a different approach -- lecular mechanisms, which utilize a dimensional change of a single polymer chain. We propose two types of molecular mechanisms: contracting and expanding. We proposed earlier a calix[4]arenebased molecular actuator for the contracting mechanism, in which p-dimer formation was proposed as a driving force. In this dissertation, we first confirm by model studies that p-dimer formation can indeed be a driving force for the calix[4]arene-based system. We propose another molecular hinge, binaphthol moiety, for the contracting model. The syntheses of polymers with binaphthols and their characterization, including signatures of oligothiophene interactions, are described. Due to its chirality, we examined the possibilities of the binaphthol polymer as a chiral amine sensor. To create actuators that make use of the expanding model, we propose new conjugated seven-membered ring systems with heteroatoms (thiepin with sulfur and azepine with nitrogen) and their syntheses and characterization will be described. Inspired by the fact that sulfoxide has very low extrusion barrier in the related system, we applied the thiepin molecules to create a peroxide sensor. (cont.) In addition, during the investigation of phenol functional groups in conducting polymers, we found interesting properties that strategic positioning of phenol groups can render a conjugation-broken meta-linked system just as conductive as a fully conjugated para-linked isomeric system. by Changsik Song. Ph.D. 2 v. (274 leaves) eng Massachusetts Institute of Technology M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission. http://dspace.mit.edu/handle/1721.1/7582 Chemistry. Design and synthesis of molecular actuators and sensors Thesis application/pdf false Publication unknown unknown <Publication xmlns="https://www.openaire.eu/cerif-profile/1.1/" id="631bf779-1d8a-439d-9cc5-cdc6047d9559"> <Type xmlns="https://www.openaire.eu/cerif-profile/vocab/COAR_Publication_Types">http://purl.org/coar/resource_type/c_1843</Type> <Language>eng</Language> <Title>Design and synthesis of molecular actuators and sensors</Title> <PublishedIn> <Publication> </Publication> </PublishedIn> <PublicationDate>2007</PublicationDate> <Authors> <Author> <DisplayName>Song, Changsik</DisplayName> <Affiliation> <OrgUnit> </OrgUnit> </Affiliation> </Author> </Authors> <Editors> </Editors> <Publishers> <Publisher> <DisplayName>Massachusetts Institute of Technology</DisplayName> <OrgUnit /> </Publisher> </Publishers> <License>http://dspace.mit.edu/handle/1721.1/7582</License> <Keyword>Chemistry.</Keyword> <Abstract>To date, the most successful conducting polymer actuators are based on polypyrrole, which operates through incorporating and expelling counterions and solvent molecules to balance the charges generated by electrochemical stimuli (swelling mechanism). Although significant progress has been made, there still exists a need for developing new materials that would overcome the intrinsic limitations in the swelling mechanism, such as slow diffusion rate, limited expansion volume, etc. Our group has contributed this area with a different approach -- lecular mechanisms, which utilize a dimensional change of a single polymer chain. We propose two types of molecular mechanisms: contracting and expanding. We proposed earlier a calix[4]arenebased molecular actuator for the contracting mechanism, in which p-dimer formation was proposed as a driving force. In this dissertation, we first confirm by model studies that p-dimer formation can indeed be a driving force for the calix[4]arene-based system. We propose another molecular hinge, binaphthol moiety, for the contracting model. The syntheses of polymers with binaphthols and their characterization, including signatures of oligothiophene interactions, are described. Due to its chirality, we examined the possibilities of the binaphthol polymer as a chiral amine sensor. To create actuators that make use of the expanding model, we propose new conjugated seven-membered ring systems with heteroatoms (thiepin with sulfur and azepine with nitrogen) and their syntheses and characterization will be described. Inspired by the fact that sulfoxide has very low extrusion barrier in the related system, we applied the thiepin molecules to create a peroxide sensor.</Abstract> <Abstract>(cont.) In addition, during the investigation of phenol functional groups in conducting polymers, we found interesting properties that strategic positioning of phenol groups can render a conjugation-broken meta-linked system just as conductive as a fully conjugated para-linked isomeric system.</Abstract> <Access xmlns="http://purl.org/coar/access_right" > </Access> </Publication>