Advances of Glucose-Based Polycarbonates: From Fundamentals to Anti-Biofouling Applications

Abstract

The production of eco-friendly materials, in particular, sugar-based polymers, has gained extensive attention because of the great abundance of natural carbohydrates and polysaccharide resources with low cost, high degrees of structural diversity and functionality, biocompatibility and degradability. In this work, we advanced the development of naturally derived glucose-based polycarbonates through the investigation of polymerization mechanisms, determination of relationships between structures, reactivities, properties, and application toward complex surfaces capable of exerting intriguing anti-biofouling characteristics to address societal challenges. The regioselectivities of organocatalytic ring-opening polymerizations (ROPs) in a series of five-membered cyclic glucose carbonate monomers were investigated. Regioirregular poly(2,3-α-D-glucose carbonates) were afforded via the ROPs of three monomers having different cyclic acetal protecting groups through the 4- and 6- positions. A combination of 1D and 2D NMR studies of the isolated unimers and dimers revealed the backbone connectivities and ring-opening preference. Furthermore, transcarbonylation reactions in the presence of the organobase catalyst, 1,5,7-Triazabicyclo[4.4.0]dec-5-ene (TBD), were confirmed by a model reaction, which was going with the ring-opening process and scrambled the regioselectivity. Computational calculations were also performed to gain the mechanistic molecular understanding of organobase catalyzed ring-opening reactions. Further, side chain engineering is extensively used to modulate the materials with desirable behaviors and performances in practical applications. Therefore, it is essential to understand the fundamental principles of substituents in sugar-based polymers that drive the polymerization processes and material properties. Glucose carbonate monomers with variable acyclic substantial functionalities at 4- and 6- positions were designed and synthesized. The side-chain substitutions significantly affected the regioselectivities and polymerization rates during organocatalytic ROPs and the thermal properties of the derived polycarbonates. Lastly, polymer amphiphilicity is well known to affect the anti-biofouling ability in the coating systems. Herein, block PEGylated poly(4,6-α-D-glucose carbonate) with different lengths of hydrophobic segments were prepared and then fabricated into coatings on glass slides to rigorously probe their surface features through advanced characterizations and evaluate their anti-biofouling performance with various organisms. Together, understandings the physicochemical properties and surface features of PGC coatings are expected to guide toward the optimized design of materials for varying challenging conditions.