AbstractIn this article, a series of biodegradable cross‐linkers, [poly(d,l‐lactide‐co‐glycolide)‐b‐poly(ethylene glycol)‐b‐poly(d,l‐ lactide‐co‐glycolide), (PLGA‐PEG‐PLGA), diacrylate] (LGE dA) with different molar ratios of d,l‐lactide (LA)/glycolide (GA) in PLGA, were prepared from the corresponding PLGA‐PEG‐PLGA diol (LGE diol) triblock copolymers and then acrylated with acryloyl chloride. The LGE diols were synthesized through ring‐opening polymerization of LA and GA using PEG as an initiator and stannous octoate [Sn(Oct)2] as a catalyst in advance. A series of novel thermosensitive and biodegradable hydrogels were then prepared from N‐isopropyl acrylamide (NIPAAm) and LGE dA as a cross‐linker. The effect of different molar ratios of LA/GA in PLGA on the swelling ratio and physical properties of the poly(NIPAAm) hydrogels were investigated. The results showed that the swelling ratios of the poly(NIPAAm) hydrogels in deionized water decreased with increasing cross‐linker content and increased with increasing GA content in the hydrogel. The compressive modulus and cross‐linking density of the hydrogels also increased with an increase in the cross‐linker content and molar ratio of LA/GA in the present hydrogel. The hydrogels can be degraded about 60% for the NL50 series of gels, but for NL78 about 53% can be degradable in 1‐month biodegradable experiment. © 2012 Wiley Periodicals, Inc. Adv Polym Techn 32: E633–E650, 2013; View this article online at wileyonlinelibrary.com. DOI 10.1002/adv.21307