title: The role of glycerol and water in flexible silk sericin film.
abstract: Silk sericin (SS) can be obtained as a byproduct during the silk fiber process, but its application has been limited due to the brittleness of the SS film. To enhance the flexibility of the SS film, glycerol (Glc) has been added as a plasticizer. The addition of Glc enhanced the elongation property of the SS film when the Glc content was 50-70 wt% of SS. Glc also induced the structural transition of SS from a random coil structure to a β-sheet structure. The inconsistent increase of elongation and β-sheet structure of the SS/Glc film were explained by the content of moisture in the SS/Glc film. The moisture content of the SS/Glc film increased proportionally when the Glc content was higher than 50 wt% of SS, which was the same Glc content range that exhibited the plasticizing effect. Therefore, the plasticizing effect on the SS film may occur not only because of Glc but also because of water. Furthermore, water also contributed to the increase in the β-sheet structure development. Our results suggest that the moisture content in the plasticized protein film may play an important role when the plasticizer has hygroscopic properties.
authors.affiliation: Department of Biosystems & Biomaterials Science and Engineering, Seoul National University, Seoul 151-921, Republic of Korea.
authors.forename: Haesung
authors.initials: H
authors.lastname: Yun
authors.affiliation: Department of Biosystems & Biomaterials Science and Engineering, Seoul National University, Seoul 151-921, Republic of Korea.
authors.forename: Moo Kon
authors.initials: MK
authors.lastname: Kim
authors.affiliation: Department of Biosystems & Biomaterials Science and Engineering, Seoul National University, Seoul 151-921, Republic of Korea.
authors.forename: Hyo Won
authors.initials: HW
authors.lastname: Kwak
authors.affiliation: Department of Biosystems & Biomaterials Science and Engineering, Seoul National University, Seoul 151-921, Republic of Korea.
authors.forename: Jeong Yun
authors.initials: JY
authors.lastname: Lee
authors.affiliation: Department of Biosystems & Biomaterials Science and Engineering, Seoul National University, Seoul 151-921, Republic of Korea.
authors.forename: Min Hwa
authors.initials: MH
authors.lastname: Kim
authors.affiliation: Department of Biosystems & Biomaterials Science and Engineering, Seoul National University, Seoul 151-921, Republic of Korea; Center for Food and Bioconvergence, Seoul National University, Seoul 151-921, Republic of Korea; Research Institute of Agriculture and Life Sciences, Seoul National University, Seoul 151-921, Republic of Korea. Electronic address: prolee@snu.ac.kr.
authors.forename: Ki Hoon
authors.initials: KH
authors.lastname: Lee
mesh_terms: D000818:Animals; D012831:Bombyx / Q000737:chemistry; D005990:Glycerol / Q000737:chemistry*; D055595:Mechanical Phenomena; D017433:Protein Structure, Secondary; D047030:Sericins / Q000737:chemistry*; D047011:Silk / Q000737:chemistry*; D017550:Spectroscopy, Fourier Transform Infrared; D014867:Water / Q000737:chemistry*; D014961:X-Ray Diffraction
chemical_list: D047030:Sericins; D047011:Silk; D014867:Water; D005990:Glycerol
keywords: Flexible film; Glycerol; Plasticizer; Protein based materials; Silk sericin; Water