The present contribution describes an innovation in the copolymerization of cyclic monomers, ε-caprolactam (ε-CL) and 2,2-dimethyltrimethylene carbonate (DTC), with ethyl diazoacetate (EDA). The characterizations of the obtained copolymers, poly(EA-ran-EDA-ran-ε-CL) and poly(EA-ran-EDA-ran-DTC) (where EA refers to the ethyl acetate group from EDA after nitrogen release), were performed using ¹H NMR and ¹³C NMR spectroscopies and size exclusion chromatography. Under optimized conditions, the copolymer of ε-CL with EDA possessing a number-average molar mass (M_n) of 1300 g mol⁻¹ and dispersity of 2.12 as well as that of DTC with EDA with M_n of 8000 g mol⁻¹ and dispersity of 1.47 were obtained. The incorporation of the azo group in the obtained copolymers was determined from the results of elemental analysis (3.30–10.22% nitrogen) and Fourier transform infrared spectroscopy. Furthermore, the thermal properties of the obtained copolymers were examined using differential scanning calorimetry. X-ray diffraction results showed that the synthesized copolymers were amorphous. © 2014 Society of Chemical Industry

Novel pH-responsive polyglycerol (PG)-based hydrogels were successfully synthesized through the reaction of epichlorohydrin with L-lactic acid (LLA) in the presence of sodium hydroxide (NaOH), and cetyltrimethylammonium bromide as a phase transfer catalyst at room temperature, followed by hydrolysis, polymerization, and crosslinking reactions. The resultant gel was characterized by carbon nuclear magnetic resonance spectroscopy, X-ray photoelectron spectroscopy, and Fourier transform infrared measurement, and it was found that incorporated LLA was bound to PG network as a pendant acidic substituent by the hydroxyl group of LLA (PGL gel). The PGL hydrogels with different LLA contents and equilibrium swelling ratios (ESRs) were prepared by changing the feed ratios of materials. The results determined by chemical titration showed that under the applied conditions the efficiency of introducing the carboxyl group into PG network was about 86% and the amount of LLA in the hydrogel reached to about 17 wt %. The swelling behavior of the hydrogels in different environmental mediums was investigated, and the results showed that the hydrogels are pH-, ionic strength-, and cationic charge-responsive. The hydrogels also have the reversible swelling/deswelling properties. These pH-responsive PG-based hydrogels will have potential applications in biomedical and related areas. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009

In this work, ring opening insertion polymerization (ROIP) of ε-caprolactone (ε-CL) using a series of hydrogen phosphonates (H-phosphonates) as initiators was investigated. The ROIP occurred by a coordination-insertion mechanism containing two steps. First, the carbonyl carbon was attacked by the phosphorus atom of the H-phosphonate tautomerization (a phosphine-like structure) and the acyl-oxygen bond was broken. An intermediate was formed by the coordination of the former carbonyl carbon and acyl-oxygen of ε-CL to phosphorus atom. Then the phosphorus-alkoxide of H-phosphonate was cleavaged to form acyl-alkoxide bond. Poly(ε-caprolactone) (PCL)-inserted H-phosphonates (PCL-HPs), which was not only the product of the occurred ROIP but also the initiator for the next ROIP, were produced. After 60 min of microwave irradiation (510 W), PCL with a number-average molar mass of 7800 g/mol and monomer conversion over 92% was obtained. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 6214–6222, 2009