Synthesis of poly(ε-caprolactone)-grafted guar gum by surface-initiated ring-opening polymerization

Taha El Assimi; Roko Blažic; Abdelkrim El Kadib; Mustapha Raihane; Redouane Beniazza; Gerrit A Luinstra; Elvira Vidović; Mohammed Lahcini

doi:10.1016/j.carbpol.2019.05.049

Synthesis of poly(ε-caprolactone)-grafted guar gum by surface-initiated ring-opening polymerization

Carbohydr Polym. 2019 Sep 15:220:95-102. doi: 10.1016/j.carbpol.2019.05.049. Epub 2019 May 15.

Authors

Taha El Assimi¹, Roko Blažic², Abdelkrim El Kadib³, Mustapha Raihane¹, Redouane Beniazza⁴, Gerrit A Luinstra⁵, Elvira Vidović², Mohammed Lahcini⁶

Affiliations

¹ Laboratory of Organometallic and Macromolecular Chemistry-Composites Materials, Faculty of Sciences and Technologies, Cadi Ayyad University, Avenue Abdelkrim Elkhattabi, B.P. 549, 40000, Marrakech, Morocco.
² University of Zagreb, Faculty of Chemical engineering and technology, Marulićevtrg 19, HR-10 000, Croatia.
³ Euro-Med Research Institute, Engineering Division, Euro-Mediterranean University of Fes (UEMF), Fez-Shore, Route de SidiHrazem, 30070, Fez, Morocco.
⁴ Mohammed VI Polytechnic University, Lot 660, Hay MoulayRachid, 43150, Ben Guerir, Morocco.
⁵ Institute of Technical and Macromolecular Chemistry, University of Hamburg, Bundesstr. 45, 20146, Hamburg, Germany.
⁶ Laboratory of Organometallic and Macromolecular Chemistry-Composites Materials, Faculty of Sciences and Technologies, Cadi Ayyad University, Avenue Abdelkrim Elkhattabi, B.P. 549, 40000, Marrakech, Morocco; Mohammed VI Polytechnic University, Lot 660, Hay MoulayRachid, 43150, Ben Guerir, Morocco. Electronic address: m.lahcini@uca.ac.ma.

PMID: 31196555
DOI: 10.1016/j.carbpol.2019.05.049

Abstract

This study reports the grafting of poly(ε-caprolactone) (PCL) on guar gum (GG) by in-situ ring-opening polymerization using tetra(phenylethynyl)tin (Sn(C≡CPh)₄) as catalyst. The hydroxyl groups of guar gum act as initiators for ε-caprolactone ring-opening polymerization and the resulting poly(ε-caprolactone) binds covalently to the polysaccharide. The highest stability of Sn(C≡CPh)₄ allows the reaction in open-air, thereby reducing the cost of the synthesis and provides polymers with high molar mass. Fourier transform infrared (FTIR) and the long-term stability of the suspension PCL-g-GG in dichloromethane confirmed the effectiveness of grafting of PCL into GG. The size exclusion chromatography (SEC) results show that the molar masse of grafted PCL could be modulated by varying the amount of guar gum. From thermogravimetric analysis and differential scanning calorimetry results the thermal stability of PCL-g-GG is greatly improved with different content of guar gum, also the melting temperature and crystallinity increased by increasing the GG content. The scanning electron microscopy (SEM) analyses showed the good adhesion between GG and PCL with 5% of GG contents. It was also revealed by contact angle measurements that the grafting of PCL to GG leads to a decrease of hydrophobicity of PCL. The micro-indentation hardness properties of the prepared PCL-g-GG were significantly improved, as compared to neat PCL.

Keywords: Guar gum; Open air; Poly(ε-caprolactone); Ring-Opening polymerization; Tetra(phenylethynyl)tin.