For nearly two decades inclusion compounds (ICs) have been formed by threading polymer chains into the cyclic starches, cyclodextrins (CDs). Non-covalently bonded crystalline ICs have been formed by threading CDs, onto guest nylon-6 (N6) chains. When excess N6 is employed, non-stoichiometric (n-s)-N6-CD-ICs with partially uncovered and dangling N6 chains result. We have been studying the constrained crystallization of the N6 chains dangling from (n-s)-N6-CD-ICs in comparison with bulk N6 samples, as a function of N6 molecular weights, lengths of uncovered N6 chains, and the CD host used. While the crystalline CD lattice is stable to ~ 300° C, the uncovered and dangling, yet constrained, N6 chains may crystallize below, or be molten above ~225° C. In the IC channels formed with host α- and γ-CDs containing 6 and 8 glucose units, respectively, single and pairs of side-by-side N6 chains can be threaded and included. In the α-CD-ICs the ~ 0.5nm channels are separated by ~ 1.4nm, while in γ-CD-ICs the ~ 1nm channels are ~ 1.7 nm apart, with each γ-CD channel including two N6 chains. The constrained dangling chains in the dense (n-s)-N6-CD-IC brushes crystallize faster and to a greater extent than those in bulk N6 melts, and this behavior is enhanced as the molecular weights/chain lengths of N6 are increased. Furthermore, when added at low concentrations (n-s)-N6-CD-ICs serve as effective nucleating agents for the bulk crystallization of N6 from the melt. Because of the biodegradable/bioabsorbable nature of CDs, (n-s)-polymer-CD-ICs can provide environmentally favorable, non-toxic nucleants for enhancing the melt crystallization of polymers and improving their properties.
| Identifer | oai:union.ndltd.org:NCSU/oai:NCSU:etd-07092009-181421 |
| Date | 12 August 2009 |
| Creators | Mohan, Anushree |
| Contributors | Bruce Novak, Jan Genzer, Alan E. Tonelli, Richard Kotek |
| Publisher | NCSU |
| Source Sets | North Carolina State University |
| Language | English |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://www.lib.ncsu.edu/theses/available/etd-07092009-181421/ |
| Rights | unrestricted, I hereby certify that, if appropriate, I have obtained and attached hereto a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dis sertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to NC State University or its agents the non-exclusive license to archive and make accessible, under the conditions specified below, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report. |
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