A novel potentially biobased aliphatic polyester poly (butylene 2-methylsuccinate) (PBMS) was synthesized from 1,4-butanediol (BDO) and 2-methylsuccinate acid (MSA) via direct esterification and polycondensation route using tetrabutyl titanate (TBT) as catalyst. The reaction conditions were investigated in detail. The proper molar ratio (1.08:1) of BDO to MSA was determined through balancing the reaction efficiency and costs of reactants. TBT was found to be an effective catalyst, and its content (0.1 mol% of MSA) was optimized based on the esterification ratio and intrinsic viscosity. The molecular weight of PBMS polymers was governed by the polycondensation time. The weight average molecular (M-w) characterized by gel permeation chromatography (GPC) ranged from 5,800 to 8,700 g/mol. The polyester was also characterized by nuclear magnetic resonance spectroscopy (H-1 NMR), differential scanning calorimeter and thermogravimetric analysis. The results showed that the glass transition temperature continuously increased with molecular weight. The polyester had excellent thermal stability, and its decomposition temperature increased with the molecular weight. As new potentially biobased polyester plasticizer, desirable mechanical properties were achieved at the weight ratio of PBMS was 80/100 and 50/100. In addition, the PBMS/poly(vinyl chloride) (PVC) blends had superior migration-resistant property to the low-molecular weight plasticizer dioctyl phthalate for PVC. (C) 2013 Society of Plastics Engineers