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Poly(l -lactic acid) (PLLA) has been attracted increasing interesting in biomedicine and tissue engineering. However, its hydrophobicity can bring about some adverse effects on protein adsorption and downstream cell adhesion. Poly(N-isopropylacrylamide) (PNIPAm) is a well-known water-soluble polymer which exhibits a hydrophobic-hydrophilic phase transition in aqueous solution upon heating. In this work, a series of P(NIPAm-co-VAc) polymers have been synthesized by using NIPA and vinyl acetate (VAc) as raw materials to insert into PLLA. The results show that the lower critical solution temperature (LCST) of synthesized polymer is 33–34 °C. When the molar ratio of NIPA to VAc and the blend ratio of synthesized polymer to PLLA are 0.76/1 and 20 wt%, respectively, the hydrophilicity of composite enhances significantly at room temperature. In particular, the composite exhibits thermoresponsive wettability below and above the LCST. Although the water contact angle presents a systematic increase with temperature increasing, it doesn't pass through the real hydrophobic domain because the conformational transition of wettable PNIPAm segment is subjected to intramolecular PVAc segment and extramolecular PLLA chain. Moreover, the synthesized polymer also offsets the brittleness of PLLA. So the method provides thermoresponsive wettability for PLLA and builds a platform for developing intelligent PLLA. [Display omitted] A P(NIPAm-co-VAc) is synthesized as filler to endow PLLA with thermo- responsive wettability. [ABSTRACT FROM AUTHOR]