Sustainable Fatty Acid Modification of Cellulose in a CO₂-Based Switchable Solvent and Subsequent Thiol-Ene Modification

Abstract

Searching for more sustainable materials as an alternative to petroleum-based products is of increasing interest due to different environmental issues. Cellulose and fatty acids are two very promising candidates for biobased material design. Herein, we report a sustainable synthesis of fatty acid cellulose esters (FACEs) via transesterification of cellulose with methyl-10-undecenoate in a CO2-based switchable solvent system. FACEs with a degree of substitution between 0.70 and 1.97 were synthesized by simple variation of reaction parameters and characterized in detail. Subsequently, a FACE with a degree of substitution (DS) of 0.70 was modified via thiol-ene reaction, demonstrating an efficient and versatile method to tune the structure and properties of the new cellulose derivatives. Films were produced from each sample via solvent casting, and their mechanical properties were examined using tensile tests. Elastic moduli (E) ranging from 90 to 635 MPa and elongations at break between 2 and 23% were observed, depending on the DS of the FACE and the type of thiol employed for the modification. Finally, contact angle measurements confirmed an increase in the surface hydrophobicity (75–91°) for the thiol-ene-modified samples.

Closing the Carbon Loop in the Circular Plastics Economy

“…In recent years, progress has been made by Meier, who introduced a more sustainable process for esterification of cellulose in a switchable 1,8diazabicyclo[5.4.0]undec-7-en (DBU)/CO 2 solvent system that holds promise for the development and processing of advanced cellulose-based plastics. [165][166][167][168][169][170][171][172][173] Tough and transparent cellulose nanopaper with high porosity was derived from aqueous dispersions of cellulose nanofibrils. [174][175][176][177][178][179] Advances in nanofibrillated cellulose production and its potential applications, ranging from nanopaper to nanocomposites, coatings, and food packaging, have been addressed by several reviews.…”

Relationship between the Structure of Modified Ricinoleic Acids via the Thiol–Ene Click Reaction and the Fogging Value of Fatliquored Leather

“…The thiol–ene click reaction has great advantages over traditional chemical reactions because of its mild reaction conditions (low temperature or room temperature and short reaction time under atmospheric conditions), high yield, and controllable target product with homogeneous polymer networks. − It has been pointed out that the reaction kinetics of the thiol–ene click reaction is strongly dependent on the structure of the thiol and alkene compounds. , Therefore, the thiol–ene click reaction is particularly attractive for the modification of monomers with unsaturated groups, such as carbon–carbon double bonds of unsaturated fatty acids in vegetable oils. , Studies have shown that using thiol–ene chemistry, the terminal double bonds of fatty acids can be converted into different functional groups under a high temperature in the absence of any initiator. , …”

“…22,23 Studies have shown that using thiol−ene chemistry, the terminal double bonds of fatty acids can be converted into different functional groups under a high temperature in the absence of any initiator. 24,25 Ricinoleic acid (RA), derived from castor oil, is one of the important renewable resources with aliphatic flexible chains. 26 In addition, RA possesses a special chemical structure and abundant functional groups, such as hydroxyl and carboxyl groups and carbon−carbon double bonds, which are a potential building block to prepare bio-based fatliquors.…”

Soybean Oil Based Allyl Acrylates and Methacrylates: Synthesis, Characterization, and Polymerization

“…[ 12–14 ] By using these reactive parts, one can synthesize different types of monomers and polymers. [ 15–26 ]…”