Although synthetic polymers are essential to our society, their manufacture and disposal can be damaging to the environment. This dissertation is concerned with the development of new high performance sustainable polymers for a wide variety of applications. The first chapter gives a brief overview of the polymer industry and introduces past work in arena of sustainable polymers with a particular focus on poly(lactide). The remaining chapters discuss my research efforts to expand on earlier work to toughen poly(lactide) using a block polymer approach. Described first is the syntheses of renewable and degradable aliphatic polyester copolymers polyols containing ε-caprolactone. These statistical copolymers are used as building blocks to prepare mechanically tunable triblock and multiblock materials (Chapter 2). Following this, an efficient semisynthetic route to a branched lactone monomer, MVL, is presented and discussed. The potential of this monomer for the synthesis of block polymer and polyurethane materials is explored (Chapters 3 and 5, respectively). A large portion of each of these chapters is dedicated to exploring the relationship between aliphatic polyester structure and key physical parameters that influence material performance (summarized in Chapter 4).