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Theory of Polymer Chains in Poor Solvent: Single-Chain Structure, Solution Thermodynamics, and Θ Point

Wang, Rui and Wang, Zhen-Gang (2014) Theory of Polymer Chains in Poor Solvent: Single-Chain Structure, Solution Thermodynamics, and Θ Point. Macromolecules, 47 (12). pp. 4094-4102. ISSN 0024-9297. doi:10.1021/ma5003968. https://resolver.caltech.edu/CaltechAUTHORS:20140731-113937619

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Abstract

Using the language of the Flory χ parameter, we develop a theory that unifies the treatment of the single-chain structure and the solution thermodynamics of polymers in poor solvents. The structure of a globule and its melting thermodynamics is examined using the self-consistent filed theory. Our results show that the chain conformation involves three states prior to the globule-to-coil transition: the fully collapsed globule, the swollen globule, and the molten globule, which are distinguished by the core density and the interfacial thickness. By examining the chain-length dependence of the melting of the swollen globule, we find universal scaling behavior in the chain properties near the Θ point. The information on density profile and free energy of the globule is used in the dilute solution thermodynamics to study the phase equilibrium of polymer solution. Our results show different scaling behavior of the solubility of polymers in the dilute solution compared to the F–H theory, both in the χ dependence and in the chain-length dependence. From the perspectives of single chain structure and solution thermodynamics, our results verify the consistency of the Θ point defined by different criteria in the limit of infinite chain length: the disappearance of the effective two-body interaction, the abrupt change in chain size, and the critical point in the phase diagram of the polymer solution. Our results show χ_Θ = 0.5 (for the case of equal monomer and solvent volume), which coincides with the value predicted from the F–H theory.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1021/ma5003968DOIArticle
http://pubs.acs.org/doi/abs/10.1021/ma5003968PublisherArticle
http://arxiv.org/abs/1406.1246arXivDiscussion Paper
ORCID:
AuthorORCID
Wang, Zhen-Gang0000-0002-3361-6114
Alternate Title:Theory of Polymer Chains in Poor Solvent: Single-Chain Structure, Solution Thermodynamics, and Theta Point
Additional Information:© 2014 American Chemical Society. Received: February 25, 2014; Revised: June 4, 2014; Published: June 13, 2014. The computing facility on which the calculations were performed is supported by an NSF-MRI grant, Award No. CHE-1040558.
Funders:
Funding AgencyGrant Number
NSFCHE-1040558
Issue or Number:12
DOI:10.1021/ma5003968
Record Number:CaltechAUTHORS:20140731-113937619
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20140731-113937619
Official Citation:Wang, R., & Wang, Z.-G. (2014). Theory of Polymer Chains in Poor Solvent: Single-Chain Structure, Solution Thermodynamics, and Θ Point. Macromolecules, 47(12), 4094-4102. doi: 10.1021/ma5003968
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:47708
Collection:CaltechAUTHORS
Deposited By: Joanne McCole
Deposited On:31 Jul 2014 19:34
Last Modified:10 Nov 2021 17:49

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