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Synthesis and Characterization of Poly( ε ‐caprolactone‐ co ‐ δ ‐ valerolactone) with Pendant Carboxylic Functional Groups
Author(s) -
Zeng Yue,
Zhang Yan,
Lang Meidong
Publication year - 2011
Publication title -
chinese journal of chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.28
H-Index - 41
eISSN - 1614-7065
pISSN - 1001-604X
DOI - 10.1002/cjoc.201190088
Subject(s) - chemistry , caprolactone , polymer chemistry , polyester , polymerization , ketone , carboxylic acid , cyclopentanone , ring opening polymerization , protecting group , differential scanning calorimetry , polymer , catalysis , organic chemistry , physics , thermodynamics , alkyl
Abstract In this paper, aliphatic polyesters functionalized with pendant carboxylic groups were synthesized via several steps. Firstly, substituted cyclic ketone, 2‐(benzyloxycarbonyl methyl)cyclopentanone (BCP) was prepared through the reaction of enamine with benzyl‐2‐bromoacetate, and subsequently converted into the relevant functionalized δ ‐valerolactone derivative, 5‐(benzyloxy carbonylmethyl)‐ δ ‐valerolactone (BVL) by the Baeyer‐Villiger oxidation. Secondly, the ring‐opening polymerization of BVL with ε ‐caprolactone was carried out in bulk using stannous octoate as the catalyst to produce poly( ε ‐caprolactone‐ co ‐ δ ‐valerolactone) bearing the benzyl‐protected carboxyl functional groups [P(CL‐ co ‐BVL)]. Finally, the benzyl‐protecting groups of P(CL‐ co ‐BVL) were effectively removed by H 2 using Pd/C as the catalyst to obtain poly( ε ‐caprolactone‐ co ‐ δ ‐valerolactone) bearing pendant carboxylic acids [P(CL‐ co ‐CVL)]. The structure and the properties of the polymer have been studied by Nuclear Magnetic Resonance (NMR), Fourier Infrared Spectroscopy (FT‐IR) and Differential Scan Calorimetry (DSC) etc . The NMR and FT‐IR results confirmed the polymer structure, and the 13 C NMR spectra have clearly interpreted the sequence of ε ‐caprolactone and 5‐(benzyloxycarbonylmethyl)‐ δ ‐valerolactone in the copolymer. When the benzyl‐protecting groups were removed, the aliphatic polyesters bearing carboxylic groups were obtained. Moreover, the hydrophilicity of the polymer was improved. Thus, poly( ε ‐caprolactone‐ co ‐ δ ‐valerolactone) might have great potential in biomedical fields.