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Published February 3, 2009 | Supplemental Material
Journal Article Open

Effects of pairwise, self-associating functional side groups on polymer solubility, solution viscosity, and mist control


Solution properties are reported for homologous series of narrowly distributed polymers with systematically varied content of self-associating groups. Anionically polymerized polybutadienes of two lengths (510 and 1250 kg/mol) serve as prepolymers that are modified by incorporation of carboxylic acid side groups using thiol−ene coupling to pendant vinyl groups. Carboxylic acid groups strongly reduce polymer solubility in hydrocarbon solvents, restricting the extent of functionalization that can be examined in single-phase solutions (e.g., in chlorododecane, functionalization must be kept <1.8 mol % even for the shorter of the two backbones). In the single-phase regime, addition of hydrogen bond "stickers" weakly affects solution viscosity. Even at concentrations that produce overlap at the scale of strand length between stickers, viscosity increases are less than 1 order of magnitude. These controlled studies (using functionalized and unmodified polymer homologues of matched, well-defined length) challenge the pre-existing understanding of the rheology of self-associating polymers. The results indicate that effects of intrachain pairing are important beyond the dilute regimebehavior unaccounted for in earlier experimental and theoretical studies. The implications for mist control of aviation fuel are that self-associating polymers of acceptable solubility in the fuel are not superior to nonassociating polymers even at concentrations several times above overlap.

Additional Information

© 2009 American Chemical Society. Received September 9, 2008; revised manuscript received December 15, 2008. Publication Date (Web): February 3, 2009. Funding for this research was provided by the FAA and NASA, the Caltech Milliken Foundation, and the Caltech Gates Grubstake Fund. We thank Dr. Steven Smith of Procter and Gamble Company for supplying the 1,2-PB precursor materials and Dr. Suneel Kunamaneni for contributing the ideas that initiated the direction of this work. Supporting Information Available: Method for the determination of the acid content of functionalized polymer; extensional viscosity results of select solutions; numerical approach for the study of the chain statistics of self-associating chains at infinite dilution in Θ-solvent. This material is available free of charge via the Internet at http://pubs.acs.org.

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