Thermoresponsive gelation of the nanocomposites consisting of poly(lactic acid-co-glycolic acid)-b-poly(ethylene glycol)-b-poly(lactic acid-co-glycolic acid) (PLGA-b-PEG-b-PLGA) triblock copolymers and LAPONITE (LAPONITE/PLGA-b-PEG-b-PLGA nanocomposites) is investigated by decreasing the molecular weights of PLGA as 1130, 900, and 470 g mol−1. As for the pure triblock copolymers, it is confirmed by UV–vis and SANS that a micellar structure with a hydrophobic core is formed even in the case of PLGA-b-PEG-b-PLGA with the lowest PLGA molecular weight of 470 g mol−1 (Triblock0.5k). As for the nanocomposites with LAPONITE, it is found that the gelation temperature (Tgel) becomes less dependent on the PLGA-b-PEG-b-PLGA concentration and more stable as the PLGA molecular weight decreases, and that Tgel of the nanocomposites almost linearly decreases as the LAPONITE concentration increases. Eventually, the nanocomposite with Triblock0.5k reaches Tgel between room temperature and physiological temperature. In addition, gradual degradation behavior is observed for the nanocomposite with Triblock0.5k. Considering the monomeric molecular weights of LA and GA at the LA/GA ratio of ≈2.0, it is concluded that the PLGA-b-PEG-b-PLGA with the lower PLGA molecular weight (i.e., Triblock0.5k) can be effectively used for thermoresponsive and degradable hydrogels targeting biomedical applications.
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