Synthesis and drug‐release properties of hyperbranched polyesters grafted with biocompatible poly(ϵ‐caprolactone)

A hyperbranched, functional, and biocompatible polymer, poly(ϵ‐caprolactone)‐grafted hyperbranched polyester (HPCL), was synthesized via a facile two‐step routine as a prospective nontoxic, biodegradable, and biocompatible drug delivery system. 1H‐NMR measurements provided direct evidence that ϵ‐caprolactone was grafted by a reaction with the peripheral functional hydroxyl groups of hyperbranched polyesters. pH‐responsive HPCL in different synthetic body fluids (SBFs) could controllably incubate aspirin. In the different SBFs, the release rates were diverse. In SBF with a pH of 7.4, the release time was nearly 110 h, whereas in SBF with a pH of 6.4 and SBF with a pH of 7.8, it was 185 and 71 h, respectively. In comparison with previously reported systems, our system had a longer release life.