title: Thermodynamic Interactions between Polystyrene and Long-Chain Poly(n-Alkyl Acrylates) Derived from Plant Oils.
abstract: Vegetable oils and their fatty acids are promising sources for the derivation of polymers. Long-chain poly(n-alkyl acrylates) and poly(n-alkyl methacrylates) are readily derived from fatty acids through conversion of the carboxylic acid end-group to an acrylate or methacrylate group. The resulting polymers contain long alkyl side-chains with around 10-22 carbon atoms. Regardless of the monomer source, the presence of alkyl side-chains in poly(n-alkyl acrylates) and poly(n-alkyl methacrylates) provides a convenient mechanism for tuning their physical properties. The development of structured multicomponent materials, including block copolymers and blends, containing poly(n-alkyl acrylates) and poly(n-alkyl methacrylates) requires knowledge of the thermodynamic interactions governing their self-assembly, typically described by the Flory-Huggins interaction parameter χ. We have investigated the χ parameter between polystyrene and long-chain poly(n-alkyl acrylate) homopolymers and copolymers: specifically we have included poly(stearyl acrylate), poly(lauryl acrylate), and their random copolymers. Lauryl and stearyl acrylate were chosen as model alkyl acrylates derived from vegetable oils and have alkyl side-chain lengths of 12 and 18 carbon atoms, respectively. Polystyrene is included in this study as a model petroleum-sourced polymer, which has wide applicability in commercially relevant multicomponent polymeric materials. Two independent methods were employed to measure the χ parameter: cloud point measurements on binary blends and characterization of the order-disorder transition of triblock copolymers, which were in relatively good agreement with one another. The χ parameter was found to be independent of the alkyl side-chain length (n) for large values of n (i.e., n > 10). This behavior is in stark contrast to the n-dependence of the χ parameter predicted from solubility parameter theory. Our study complements prior work investigating the interactions between polystyrene and short-chain polyacrylates (n ≤ 10). To our knowledge, this is the first study to explore the thermodynamic interactions between polystyrene and long-chain poly(n-alkyl acrylates) with n > 10. This work lays the groundwork for the development of multicomponent structured systems (i.e., blends and copolymers) in this class of sustainable materials.
authors.affiliation: Department of Chemical and Biomolecular Engineering, University of Houston, 4800 Calhoun Road, S222 Engineering Building 1, Houston, Texas 77204-4004, United States.
authors.forename: Shu
authors.initials: S
authors.lastname: Wang
authors.affiliation: Department of Chemical and Biomolecular Engineering, University of Houston, 4800 Calhoun Road, S222 Engineering Building 1, Houston, Texas 77204-4004, United States.
authors.forename: Megan L
authors.initials: ML
authors.lastname: Robertson
mesh_terms: D000179:Acrylates / Q000737:chemistry*; D001672:Biocompatible Materials / Q000737:chemistry*; D008689:Methacrylates / Q000737:chemistry; D010938:Plant Oils / Q000737:chemistry; D011108:Polymers / Q000737:chemistry; D011137:Polystyrenes / Q000737:chemistry*; D012995:Solubility; D013816:Thermodynamics; D014867:Water / Q000737:chemistry
chemical_list: D000179:Acrylates; D001672:Biocompatible Materials; D008689:Methacrylates; D010938:Plant Oils; D011108:Polymers; D011137:Polystyrenes; D014867:Water; C036658:acrylic acid
keywords: Flory−Huggins interaction parameter; alkyl chain length; block copolymers; poly(n-alkyl acrylates); poly(n-alkyl methacrylates); renewable resource polymers; side-chain; thermodynamic interactions