Biomass-derived polymers are drawing increased attention from researchers due to unique performance attributes, potential for biodegradability, new low-cost feedstocks, and improved sustainability. Biobased feedstocks are employed in both major applications of polymers thermosets and thermoplastics. For thermoset coatings and adhesives, biobased resins such as biobased alkyds, epoxy resins, benzoxazine resins, starch derivatives, and proteins from plants and animals, are promising candidates to replace petroleum-derived counterparts. Thermoplastics such as polyethylene are mainly produced from fossil resources, generally have poor degradability and are difficult to effectively recycle. Currently, in the United States, less than 10% plastics are recycled, and more than 70% are landfilled. The plastics escaping from the waste management system will ultimately find their ways to oceans. Therefore, there is an urgent demand to develop degradable, recyclable, and biobased alternatives to replace conventional plastics. Although biobased materials continue to grow, petroleum-derived polymers still account for the majority of markets. To compete with the conventional thermosets and thermoplastics, biobased alternatives are required to overcome technical challenges, to provide equivalent or better performance, to become more environmentally friendly, and to offer equivalent or lower price. In this thesis, we applied 1,5-pentanediol (PDO), which is an emerging biobased and low-cost monomer, to thermoset coatings, adhesives, and biodegradable plastics. Polyesters based on PDO were designed, synthesized, and investigated. We developed a reactor for melt polymerization and understood the effects of reaction conditions to synthesize target polyesters with molecular wights ranging from 1KDa to over 100KDa.