Biobased, elastomeric polymer poly(glycerol succinate-co-maleate) (PGSMA) was produced using a "green" synthesis with added cellulose nanocrystals (CNCs) to create a novel PGSMA-CNC material. PGSMA-CNC was synthesized with the aim of developing a new strategy for successfully dispersing CNCs within a poly(lactic acid) (PLA) matrix for optimal reinforcement of tensile strength and modulus while having the added benefit of the proven toughness enhancements of PLA/PGSMA blends. Optical microscopy and fractionation in tetrahydrofuran showed that CNCs agglomerated during PGSMA-CNC synthesis and remained in agglomerates during PLA/PGSMA-CNC reactive blending. Fourier transform infrared, differential scanning calorimetry, and dynamic mechanical analyses also showed that PGSMA-CNC inhibited the formation of PGSMA crosslinks and PLA-g-PGSMA during reactive blending. These two effects resulted in loss of impact strength and only a 4% increase in tensile modulus over PLA/PGSMA at the highest CNC content. Further work in preventing CNC aggregation could help improve mechanical properties of the final blend.