[
    {
        "id": "authors:pz2ya-prr72",
        "collection": "authors",
        "collection_id": "pz2ya-prr72",
        "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230324-284904000.2",
        "type": "monograph",
        "title": "Tuning Ether Motifs in Polymer Membranes for CO\u2082 Separation",
        "author": [
            {
                "family_name": "Basdogan",
                "given_name": "Yasemin",
                "orcid": "0000-0002-2071-9675",
                "clpid": "Basdogan-Yasemin"
            },
            {
                "family_name": "Wang",
                "given_name": "Zhen-Gang",
                "orcid": "0000-0002-3361-6114",
                "clpid": "Wang-Zhen-Gang"
            }
        ],
        "abstract": "Polymer membranes are an attractive, energy efficient alternative to traditional unit operations for gas separation. Polyethers have been leading membrane materials for CO\u2082 separation due to their unique ether oxygen moiety that exhibits affinity towards CO\u2082. We systematically study the effect of an ether-oxygen moiety on solubility using perturbed-chain statistical associating fluid theory equation of state calculations and on diffusivity using molecular dynamics simulations for CO\u2082 separation. We investigate five different polymer materials with varying oxygen content, including commonly used polymers such as poly(ethylene oxide) as well as polymers with higher ether-oxygen content. Our results show that increasing the ether-oxygen moiety in the polymer membrane significantly increases the CO\u2082/N\u2082 solubility selectivity. Of the studied materials, polyoxymethylene has the highest oxygen to carbon ratio, and it has the highest CO\u2082/N\u2082 solubility selectivity. Molecular dynamics simulations indicates CO\u2082/N\u2082 diffusivity selectivity increases with increasing ether-oxygen content in the polymer, although the individual gas diffusion slows down. Moreover, we find that increasing the temperature increases the gas diffusion; however, the polymers lose their selective interactions with CO\u2082, thus resulting in lower selectivity. We demonstrate that the ether-oxygen is a key functional group controlling the CO\u2082/N\u2082 solubility selectivity of polymer membranes.",
        "doi": "10.26434/chemrxiv-2022-4ml8d",
        "publication_date": "2022-11-04"
    },
    {
        "id": "authors:bn4n9-91d25",
        "collection": "authors",
        "collection_id": "bn4n9-91d25",
        "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20140623-152015461",
        "type": "monograph",
        "title": "Theory of Polymer Chains in Poor Solvent: Single-Chain Structure, Solution Thermodynamics and \u0398 Point",
        "author": [
            {
                "family_name": "Wang",
                "given_name": "Rui",
                "clpid": "Wang-Rui"
            },
            {
                "family_name": "Wang",
                "given_name": "Zhen-Gang",
                "orcid": "0000-0002-3361-6114",
                "clpid": "Wang-Zhen-Gang"
            }
        ],
        "abstract": "Using the language of the Flory chi 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 Theta point. The information of 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 chi dependence and the chain-length dependence. From the perspectives of single chain structure and solution thermodynamics, our results verifies the consistency of the Theta point defined by different criteria in the limit of infinite chain length: the disappearance of the second viral coefficient, the abrupt change in chain size and the critical point in the phase diagram of the polymer solution. Our results show the value of chi at the Theta point is 0.5 (for the case of equal monomer and solvent volume), which coincides with the value predicted from the F-H theory.",
        "doi": "10.48550/arXiv.1406.1246",
        "publication_date": "2014-06-05"
    },
    {
        "id": "authors:am2gm-02p61",
        "collection": "authors",
        "collection_id": "am2gm-02p61",
        "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20131112-092536567",
        "type": "monograph",
        "title": "Continuous Self Energy of Ions at the Dielectric Interface",
        "author": [
            {
                "family_name": "Wang",
                "given_name": "Rui",
                "clpid": "Wang-Rui"
            },
            {
                "family_name": "Wang",
                "given_name": "Zhen-Gang",
                "orcid": "0000-0002-3361-6114",
                "clpid": "Wang-Zhen-Gang"
            }
        ],
        "abstract": "We present a simple, unified theory for the self-energy of an ion near a dielectric interface. Our theory accounts for both the short-range (solvation) and long-range (image force) electrostatic forces, charge polarization induced by these forces, and the cavity energy. In contrast to previous models, our self energy is continuous across the interface and thus applicable to both the water and air (oil) sides of the interface. With no fitting parameters, we predict the specific ion effect on the interfacial affinity of halogen anions at the water/air interface, and the strong adsorption of hydrophobic ions at the water/oil interface, in agreement with experiments and atomistic simulations.",
        "doi": "10.48550/arXiv.1310.8274",
        "publication_date": "2013-10-30"
    }
]