Polylactide (PLA) is currently considered to be the most interesting bio-based polymers from short-term to durable applications such as electronics and packaging due to its unique properties such as high strength, biocompatibility and biodegradability. Despite all of these advantages, PLA has both low glass transition temperature and heat deflection temperature. Therefore the mechanical properties of PLA-based materials are relatively poor at temperatures greater than 60°C, impeding its use as a green engineering thermoplastic. In this respect reinforcing PLA with nanofillers represents a promising method to address these issues. Cellulose nanocrystals (CNCs) possess many attractive features for making nano-composites such as its large abundance; non-toxicity, biodegradability, low density, and a very large surface area that can be further functionalized. However, their surface-functionalization is not straightforward and environmentally-friendly because the inevitable use of organic solvents (through numerous solvent-exchanges) is required before dispersion of CNCs into polymeric matrix. Direct surface-functionalization starting from aqueous CNCs suspensions seems to be the best way to alleviate these issues. Recently, a green one-step method based on both Fischer Esterification and acid hydrolysis to obtain functionalized and ready-to-use CNs has been reported by some us. The aim of the present communication was hence to investigate the reinforcing effect of CNCs on PLA-based materials. Direct melt-blending PLA with CNCs not or functionalized with both acetic acid CNCs and lactic acid (LA-CNCs) moieties in order to investigate their effects on the thermomechanical properties of the blend. The corresponding thermomechanical properties were investigated by DMTA and it was found that LA-CNCs possess the highest storage modulus. This increase in materials properties can potentially expand the applications of PLA based materials towards, e.g., energy applications.