Cross-linked and functionalized polyester materials constructed using ketoxime ether linkages

Abstract

A modular and simple approach to the graft functionalization and cross-linking of ketonecontaining poly(e-caprolactone)s has been investigated for the preparation of novel gel and nanoparticulate materials. Poly(e-caprolactone-co-2-oxepane-1,5-dione) (P(CL-co-OPD)), was grafted by reaction with 1-aminooxydodecane and cross-linked by reaction with 1,6-bis(aminooxy)hexane, each at room temperature in tetrahydrofuran at 1 and 10 wt% polymer in the absence of an acid catalyst, and at 1, 5 and 10 wt% polymer in the presence of p-toluenesulfonic acid. The grafting process served as a model system for the cross-linking reactions, affording products that were fully characterizable and retained the physical properties of (P(CL-co-OPD)), with a slight increase in measured molecular weight and characteristic spectroscopic signatures for the dodecyl chains and the newly introduced ketoxime functionalities. Early stages of the intermolecular cross-linking were followed by gel permeation chromatography and atomic force microscopy. Ultimately, insoluble, but tetrahydrofuran-swollen gelled products were obtained, which were characterized by infrared spectroscopy, differential scanning calorimetry and thermogravimetric analysis. These materials exhibited interesting melting transition profiles, undergoing melting at lower temperatures and broader temperature ranges than observed for their polymer precursors. This study represents an advance in the development of rapid and efficient chemistry for the preparation of functional and robust hydrolyticallydegradable polymer materials with degradable linkages.

Oxime functionalization strategy for iodinated poly(epsilon-caprolactone) X-ray opaque materials

“…It is also a promising polymer conjugation reaction with many examples appearing in the recent synthetic polymer literature, some of which utilize polyester backbones. [57][58][59][60][61][62][63][64][65][66][67][68][69][70][71][72][73][74][75] This versatility is exploited in our work in the preparation of ketone-functionalized polyesters capable of reacting with hydroxylamines to provide a covalent linkage between the polymer and contrast agent. Our interest in the oxime conjugation partly stems from the synthetic simplicity in preparing aminooxy derivatives, including the desired O-(2-iodobenzyl) hydroxylamine used to impart the desired X-ray opacity, while maintaining the biodegradability and potentially the biocompatibility of the polyester material itself.…”

Synthesis and conjugation of a triiodohydroxylamine for the preparation of highly X‐ray opaque poly(ε‐caprolactone) materials

“…This depression in the melting transition can be attributed to the disruption of the polymer crystallinity by the attached large aromatic side chains, as was reported and observed previously. 14,15,23,24 The partially and fully conjugated triiodo samples, 7a and 8a, respectively, also displayed lower T m values of 51.9 and 35.0 8C with the partial conjugation 7a giving the intermediate T m .…”

Recent Advances in the Functionalization of Aliphatic Polyesters by Ring-Opening Polymerization

“…Nowadays, these ω functionalizations have been extended to hydrazines 40 and to other aminooxy small molecules. [41,42] It is also worth noting that the coupling of amines by reductive amination was investigated by Wooley et al but the efficiency turned out to be not sufficient. [43] One important issue is the low solubility of copolyesters with a high content of oxepane-1,2-dione in many organic solvents, which might limit the extent of functionalization.…”