Highly Hydrophobic Organosilane-Functionalized Cellulose: A Promising Filler for Thermoplastic Composites

Abstract

The aim of this work is to design and optimize the process of functionalization of cellulose fibers by organosilane functional groups using low-pressure microwave plasma discharge with hexamethyldisiloxane (HMDSO) precursor in order to prepare a compatible hydrophobic filler for composites with nonpolar thermoplastic matrices. Particular attention was paid to the study of agglomeration of cellulose fibers in the mixture with polypropylene. In our contribution, the dependence of the surface wettability on used process gas and treatment time was investigated. Scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) analyses were applied to characterize the surface morphology and chemical composition of the cellulose fibers. It was observed that the plasma treatment in oxygen process gas led to the functionalization of cellulose fibers by organosilane functional groups without degradation. In addition, the treated cellulose was highly hydrophobic with water contact angle up to 143°. The use of treated cellulose allowed to obtain a homogeneous mixture with polypropylene powder due to the significantly lower tendency of the functionalized cellulose fibers to agglomerate.

Hydrophobic molecular treatments of cellulose-based or other polysaccharide barrier layers for sustainable food packaging: A Review

“…Belgacem and Gandini (2005), Kalia et al (2009), and Belgacem et al (2011) reviewed work involving such systems. In the case of silane-based treatments, plasma application can be used to activate hexamethyldisiloxane so that it reacts effectively and becomes bound to the substrate (Creatore et al 2001(Creatore et al , 2002Mai and Militz 2004;Schneider et al 2007Schneider et al , 2009Deilmann et al 2008a,b;Avramidis et al 2009;Siliprandi et al 2011;Chen et al 2017;Mitschker et al 2018;Yang et al 2018;Kakiuchi et al 2019;Cerny et al 2021;Ma et al 2021). Plasma also has been used to graft perfluorinated alkyl chains onto cellulose (Kong et al 1992;Sahin et al 2002Sahin et al , 2007Navarro et al 2003;Zhang et al 2003;Balu et al 2008;Toriz et al 2008;Mirvakili et al 2013;Siro et al 2013).…”

“…See Table C of the Appendix for summary information from related studies. The most widely used compound for this type of system is hexamethyldisiloxane (HMDS) (Creatore et al 2001(Creatore et al , 2002Deilmann et al 2008a,b;Avramidis et al 2009;Cerny et al 2021;Ma et al 2021).…”

“…Thereby, one does not need to depend on any inherent reactivity in the applied compound. Atmospheric plasmas having relatively low energy are used most commonly in such research (Avramidis et al 2009;Chen et al 2017;Cerny et al 2021;Ma et al 2021). Oxygen plasmas also have been used (Creatore et al 2001(Creatore et al , 2002Deilmann et al 2008a,b).…”

“…23. With just a few exceptions (Chen et al 2017;Cerny et al 2021;Ma et al 2021), the researchers who have reported plasma-based hydrophobic treatments of polysaccharide-based substrates generally have not mentioned the time duration of treatment. Table 5 lists some typical periods of treatment employed in studies of plasma treatments to change the wettability properties of a variety of substrates.…”

Preparation of Breathable Cellulose Based Polymeric Membranes with Enhanced Water Resistance for the Building Industry

“…The high water absorption capacity of bio-based materials also makes them incompatible with hydrophobic polymers causing poor interfacial adhesion in the composites [ 31 , 32 ]. Numerous studies have investigated the effect of alkali [ 33 ], acetylation [ 34 ], ionic liquids and salts [ 35 , 36 , 37 ], silane [ 38 ], sol-gel [ 39 ], and surfactant [ 40 , 41 ] treatment of bio-based materials that improve their hydrophobicity and compatibility with polymers.…”