A synthetic strategy to incorporate catechol functional groups into benzoxazine thermoset monomers was developed, leading to a family of bioinspired small‐molecule resins and main‐chain polybenzoxazines derived from biologically available phenols. Lap‐shear adhesive testing revealed a polybenzoxazine derivative with greater than 5 times improved shear strength on aluminum substrates compared to a widely studied commercial benzoxazine resin. Derivative synthesis identified the catechol moiety as an important design feature in the adhesive performance and curing behavior of this bioinspired thermoset. Favorable mechanical properties comparable to commercial resin were maintained, and glass transition temperature and char yield under nitrogen were improved. Blending of monomers with bioinspired main‐chain polybenzoxazine derivatives provided formulations with enhanced shear adhesive strengths up to 16 MPa, while alloying with commercial core–shell particle‐toughened epoxy resins led to shear strengths exceeding 20 MPa. These results highlight the utility of bioinspired design and the use of biomolecules in the preparation of high‐performance thermoset resins and adhesives with potential utility in transportation and aerospace industries and applications in advanced composites synthesis.

The utility of metabolic synthons as the building blocks for new biomaterials is based on the early application and success of hydroxy acid based polyesters as degradable sutures and controlled drug delivery matrices. The sheer number of potential monomers derived from the metabolome (e.g., lactic acid, dihydroxyacetone, glycerol, fumarate) gives rise to almost limitless biomaterial structural possibilities, functionality, and performance characteristics, as well as opportunities for the synthesis of new polymers. This review describes recent advances in new chemistries, as well as the inventive use of traditional chemistries, toward the design and synthesis of new polymers. Specific polymeric biomaterials can be prepared for use in varied medical applications (e.g., drug delivery, tissue engineering, wound repair, etc.) through judicious selection of the monomer and backbone linkage.

A synthetic strategy to incorporate catechol functional groups into benzoxazine thermoset monomers was developed, leading to a family of bioinspired small‐molecule resins and main‐chain polybenzoxazines derived from biologically available phenols. Lap‐shear adhesive testing revealed a polybenzoxazine derivative with greater than 5 times improved shear strength on aluminum substrates compared to a widely studied commercial benzoxazine resin. Derivative synthesis identified the catechol moiety as an important design feature in the adhesive performance and curing behavior of this bioinspired thermoset. Favorable mechanical properties comparable to commercial resin were maintained, and glass transition temperature and char yield under nitrogen were improved. Blending of monomers with bioinspired main‐chain polybenzoxazine derivatives provided formulations with enhanced shear adhesive strengths up to 16 MPa, while alloying with commercial core–shell particle‐toughened epoxy resins led to shear strengths exceeding 20 MPa. These results highlight the utility of bioinspired design and the use of biomolecules in the preparation of high‐performance thermoset resins and adhesives with potential utility in transportation and aerospace industries and applications in advanced composites synthesis.

Biologically occurring non‐canonical di‐α‐amino acids were converted into new di‐N‐carboxyanhydride (di‐NCA) monomers in reasonable yields with high purity. Five different di‐NCAs were separately copolymerized with tert‐butyl‐l‐glutamate NCA to obtain covalently crosslinked copolypeptides capable of forming hydrogels with varying crosslinker density. Comparison of hydrogel properties with residue structure revealed that different di‐α‐amino acids were not equivalent in crosslink formation. Notably, l‐cystine was found to produce significantly weaker hydrogels compared to l‐homocystine, l‐cystathionine, and l‐lanthionine, suggesting that l‐cystine may be a sub‐optimal choice of di‐α‐amino acid for preparation of copolypeptide networks. The di‐α‐amino acid crosslinkers also provided different chemical stability, where disulfide crosslinks were readily degraded by reduction, and thioether crosslinks were stable against reduction. This difference in response may provide a means to fine tune the reduction sensitivity of polypeptide biomaterial networks.

Carboxylic acids are widely used as building blocks in several types of coating systems, including as hardeners for epoxy resins. The chemical structure of the acid significantly impacts the coating properties. While petrochemical-derived acids have traditionally dominated the field, the structural diversities of biologically occurring molecules, as well as potential for improved sustainability, are leading to an increased focus on biobased raw materials. Recent advances in microbial engineering are paving the road toward commercial availability of additional suites of poly­(carboxylic acid) structures which have not been evaluated in epoxy coating systems. Herein, we select a series of 12 biological di- and tricarboxylic acids whose structures could prove advantageous in coating applications to be evaluated as components for epoxy–acid coatings. We tested several of the selected acids as hardeners for two polyfunctional epoxy resins: biobased epoxidized sucrose soyate (ESS) and petrochemical Araldite MY 721. This was done using a catalyst-free epoxy–acid–solvent system with an equimolar epoxy:COOH ratio. If the biobased acid is water soluble, the use of an ESS–acid system with water as a solvent could give rise to 100% biobased coatings. Kinetic studies carried out using ESS–acid systems demonstrated that under selected thermal curing conditions a complete conversion of carboxylic groups of biobased acids is achieved. Changing the solvent from water to 1,4-dioxane had little effect on the properties of the epoxy–acid formulations. Films made from the developed formulations demonstrated excellent solvent resistance and adhesion to metal substrates. Using isomeric acids (both cis–trans and structural isomers) for cross-linking epoxy resins resulted in highly varying properties in cured coatings. The hardness and flexibility of the cross-linked films can be tuned by changing the chemical structure of the acid and epoxy resin. The results highlight the potential for unexplored biobased compounds to expand the currently accessible property portfolio of acid-derived coatings while also improving sustainability.

Biodegradable hydrogels are an important class of biomaterials with a diverse range of applications. In some cases, a rapid hydrogel degradation rate is advantageous. Polycarbonate hydrogels based on dihydroxyacetone (DHA), a natural metabolite, have been reported to undergo surprisingly fast hydrolytic degradation. In the present work, insight into the key features of DHA that contribute to the observed degradation rates is gained. In vitro degradation (mass loss) of three different chemically cross‐linked polycarbonate hydrogels is investigated to shed light on the role of the ketone functional group, as well as the carbon‐chain length between the ketone and carbonate bonds. The ketone is found to be the major cause of rapid degradation. Also, mass loss is accelerated by increased temperature and pH, offering insight into potential tuning parameters and storage conditions. The results show that DHA is a promising monomeric unit for the design of rapidly degrading, biocompatible, and functional biomaterials.

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The applicability of polyesters across a wide range of fields creates a demand for novel polyester structures that can offer advanced product performance. Two critical factors to the development of unique polymer architectures are the speed at which new polymeric systems can be synthesized and the available selection of monomers from which polymers are designed. Herein, we successfully demonstrate the applicability of a high‐throughput (HT) approach to polyesterification reaction between dicarboxylic acids and diols in reaction conditions similar to those used in industry. Furthermore, we apply our HT design to a series of bio‐based monomers whose unique structures offer potential for enhanced properties in polyester‐based systems. Using a custom‐built array of small‐scale film reactors, we conducted a parallel screening of 13 bio‐based dicarboxylic acids as potential monomers in the synthesis of polyester polyols through copolymerization with 1,6‐hexanediol. The polyester polyols were characterized for their molecular weight and thermal properties. Carrying out polyesterification reactions in small‐scale film reactors is seen as a quick and powerful tool for screening the effectiveness of a series of potential monomers, as this method offers highly controllable and reproducible reaction conditions in every reactor coupled with the ability to use a minimum amount of reagents.