Lignin is the second most abundant renewable biomass polymer. Despite its potential as a sustainable raw material due to its abundance, low price, and high aromatic concentration, its complex structure and poorly defined excessive reaction sites for lignin limit its application. Castor oil is a type of triacylglycerol that consists of various fatty acids and glycerol. Most of the fatty acids are ricinoleic acid (&gt;90 %), and the overall amount of saturated and unsaturated fatty acids that are not ricinoleic acid is relatively small. Especially, castor oil's hydroxyl group is very useful for further chemical modification. In this work, we have synthesized a 100% biomass-based polyester, lignin-graft-castor oil. The lignin was chemically modified by succinic acid and capping agent, acetic acid. Acetic acid capped the hydroxyl group to reduce the number of excessive reaction sites in the lignin, and succinic acid is used to introduce carboxylic acid for graft copolymerization to castor oil’s hydroxyl group. The castor oil was used in its pristine form without any modification. These two biomasses are covalently linked via carbodiimide mediated esterification. The synthesized lignin-graft-castor oil was thermoplastic demonstrating decent melting temperatures (57~71 <sup>o</sup>C) and glass transition temperatures (39~60 <sup>o</sup>C). The mechanical properties of new capped lignin-graft-castor oil can be controlled by changing the crosslinking density and the mass ratio of lignin and castor oil. The highest modulus is 228.43 MPa, which is higher than that of low-density polyethylene (LDPE). Furthermore, its physical properties, including density and contact angle of water, are also changed by the mol % of the capping agent and the mass ratio of lignin and castor oil. The new synthesized 100% biomass-based polymer, lignin-graft-castor oil, will be a new class of completely degradable polymer that will solve the non-degradable polymer waste issue.

100% Biomass-based completely degradable polymers: Lignin-graft-castor oil

Where thousands of chemistry professionals meet to share ideas and advance scientific and technical knowledge. Spring 2023 abstracts, posters, and presentations will launch at the end of March.

ACS Spring 2023

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.