- This study is related to pressure-sensitive adhesive (PSA) for transdermal drug delivery system (TDD) application. PSA is essential to the safety, efficacy and product quality. The therapeutic effect of the drug highly depends on the adhesive performance of PSAs. In TDD, the reduction of the surface area of contact as a result of poor adhesion can lead to improper dosing of patients. The required properties needed for PSA are biocompatibility, high elasticity, surface energy, tack, and removability. Therefore, polylactic acid-polyethylene oxide-polylactic acid (PLA-PEO-PLA) triblock copolymer (PELA) is chosen in this study due to its biocompatibility, biodegradability and varieties of drug compatibility. The PELA with various molecular weights having EO:LA molar ratio of 1:1 were synthesized by ring-opening polymerization, and then coated onto NR surface. The chemical structure and composition of PELA were examined by Proton nuclear magnetic resonance spectroscopy. The presence of PELA on the NR surface was examined by Attenuated total reflection-Fourier transform infrared spectroscopy. The Atomic force microscopic (AFM) morphologies supported ATR-FTIR result in that PELA was introduced onto NR surface and there is no phase separation between PLA and PEO segment. Adhesive performance of PSA is determined by peel adhesion (ASTM D3330 modified) and AFM force mode. The adhesive properties of NR modified surface increased with increasing MW of PELA. The effect of various PELA molecular weights (MW) on the elastic modulus and creep behavior was investigated using Nanoindentation. The modulus and creep of NR modified surface increased with increasing MW of PELA. The results from water contact angle measurement indicated the improved hydrophilicity of NR. The NR modified by PELA has promising potential to be a new biomaterial, which combines good biocompatibility, adhesive property, desirable hydrophilicity, and mechanical stability.