title: Choline chloride based ionic liquid analogues as tool for the fabrication of agar films with improved mechanical properties.
abstract: In the present paper, we test the suitability of ChCl/urea (DES-U) and ChCl/glycerol (DES-G) eutectic mixtures, each one prepared at 1:2 molar ratio, for the production of agar films. A three-step process is proposed: pre-solubilization of polymer in DES followed by compression-molding and subsequent drying. The mechanical properties, water resistance and microstructure of the films were evaluated at different polymer concentrations (i.e. 2-6%, w/w). DES-U showed by far, the best film forming ability. Agreeing with the diffusion and SEM data, films with the best mechanical properties were found at the lowest and highest agar concentrations (tensile strengths of 24.2-42 MPa and elongations of 15.4-38.9%). The water sorption and contact angle studies suggested increased hydrophilicity for the film containing the lowest concentration of agar. The use of choline chloride based ionic liquid analogues as solvent and plasticizer might be a promising tool for the development of new non-aqueous materials based on seaweed polysaccharides.
authors.affiliation: REQUIMTE, Faculdade de Engenharia, Universidade do Porto, Rua Dr. Roberto Frias, 4200-465 Porto, Portugal; Eastern Regional Research Center, Agricultural Research Service, United States Department of Agriculture, 600 East Mermaid Lane, Wyndmoor, PA 19038, USA.
authors.forename: Ana M M
authors.initials: AM
authors.lastname: Sousa
authors.affiliation: REQUIMTE, Faculdade de Engenharia, Universidade do Porto, Rua Dr. Roberto Frias, 4200-465 Porto, Portugal.
authors.forename: Hiléia K S
authors.initials: HK
authors.lastname: Souza
authors.affiliation: Eastern Regional Research Center, Agricultural Research Service, United States Department of Agriculture, 600 East Mermaid Lane, Wyndmoor, PA 19038, USA.
authors.forename: Nicholas
authors.initials: N
authors.lastname: Latona
authors.affiliation: Eastern Regional Research Center, Agricultural Research Service, United States Department of Agriculture, 600 East Mermaid Lane, Wyndmoor, PA 19038, USA.
authors.forename: Cheng-Kung
authors.initials: CK
authors.lastname: Liu
authors.affiliation: REQUIMTE, Faculdade de Engenharia, Universidade do Porto, Rua Dr. Roberto Frias, 4200-465 Porto, Portugal.
authors.forename: Maria P
authors.initials: MP
authors.lastname: Gonçalves
authors.affiliation: Eastern Regional Research Center, Agricultural Research Service, United States Department of Agriculture, 600 East Mermaid Lane, Wyndmoor, PA 19038, USA. Electronic address: LinShu.liu@ars.usda.gov.
authors.forename: LinShu
authors.initials: L
authors.lastname: Liu
mesh_terms: D000362:Agar / Q000737:chemistry*; D002794:Choline / Q000737:chemistry*; D052578:Ionic Liquids / Q000737:chemistry*; D010968:Plasticizers / Q000737:chemistry; D011108:Polymers / Q000737:chemistry
chemical_list: D052578:Ionic Liquids; D010968:Plasticizers; D011108:Polymers; D000362:Agar; D002794:Choline
keywords: Agar; Contact angle; DES; Mechanical properties; Plasticizer; Water resistance