Syntheses of biodegradable graft copolymers from sodium caseinate and poly ɛ-caprolactone or poly lactic acid. Applications to the compatibilization of sodium caseinate/polyester blends

• Published in: Materials today chemistry 2023-01, Vol.27, p.101345, Article 101345
• Main Authors: Viora, L., Tichané, T., Taguet, A., Garric, X., Coudane, J., Van Den Berghe, H.
• Format: Article
• Language: English
• Subjects: Aliphatic polyesters; Blends; Casein; Chemical modification; Chemical Sciences; Grafting
• ISSN: 2468-5194; 2468-5194
• DOI: 10.1016/j.mtchem.2022.101345

Casein (and its sodium salt, sodium caseinate, SC) is an inexpensive natural milk protein that is used as a biodegradable biomaterial, especially to produce packaging films. However, to enhance some of its properties, it needs to be blended with other polymers, which should preferably be biodegradable such as poly lactic acid (PLA) and poly ε-caprolactone (PCL). New SC-g-PLA and SC-g-PCL graft copolymers have been prepared and unambiguously characterized, in particular by 1H and DOSY NMR. The grafting degrees are high (between 24 and 35% by weight) and result in variations of properties, such as hydrophobicity and thermal properties. The microstructures of SC/PLA and SC/PCL blends were studied and compared, with and without the addition of the SC-g-PLA and SC-g-PCL copolymers to test the compatibilization capacity of these new biodegradable copolymers. [Display omitted] •Syntheses of casein-g-polyester copolymers via a “phase transfer catalysis” reaction.•High grafting degrees allowing high weight proportions of polyester.•Compatibilizing effect of graft copolymers on non-compatible casein/polyester blends.