Aliphatic polyester block polymers constitute a highly useful and amazingly versatile class of self-assembled materials. Analogous to styrenic block polymers in both design and function, the property profiles of these degradable materials can be precisely tailored by altering the chemical structure of the components. Driven by this ideal, we have examined the impact of n-alkyl substituents on the polymerization thermodynamics and kinetics of substituted 5valerolactone monomers and developed guiding design principles based on critical structure property relationships in the resulting aliphatic polyesters. Under bulk room temperature conditions the polymerization rate depends strongly on substituent position and exhibits a more modest dependence on alkyl length (from -CH3 to -(CH2)(8)CH3). The enthalpy and entropy of polymerization are significantly influenced by substituent position, but both are largely insensitive to n-alkyl length. However, the physical properties of the resulting aliphatic polyesters depend much more on substituent length than on substituent position. Notably, we demonstrate that polymer entanglement molar mass and solubility parameter can be systematically tuned by changing the substituent length. We discuss how these key structure property relationships can be used to inform the design of advanced sustainable materials for future technologies important in the arena of environmentally friendly materials.