Structural characterisation of poly(amidoamine) networks via high‐resolution magic angle spinning NMR

Abstract

A comprehensive structural characterisation of cross-linked insoluble poly(amidoamine) (PAA) networks was performed by high-resolution magic angle spinning (HRMAS) NMR spectroscopy. Model samples with 20%, 40% and 80% cross-linking degrees were prepared and the best conditions to obtain high-resolution spectra in the gel phase determined. Whereas the samples with 20% and 40% cross-linking degrees could be exhaustively resolved and described, the sample with 80% cross-linking degree could not be characterised by this technique owing to insufficient mobility of the polymer segments. Even with this limitation, the method developed in this study can be reasonably considered as a general one, which enables exhaustive characterisation of cross-linked PAA networks of biomedical interest.

Diels−Alder Click Cross-Linked Hyaluronic Acid Hydrogels for Tissue Engineering

“…The cross-link density could be investigated using 1 H HR-NMR 88 . By grafting molecules onto insoluble supports, sufficient rotational mobility can be achieved by swelling the support in a suitable solvent, providing a high-resolution characterization tool for macromonomers 89 , and hydrogel synthesis 90 . This technique was utilized to determine the degree of cross-linking for HA hydrogels cross-linked via CuAAC 31 .…”

HR-MAS NMR Spectroscopy in Material Science

“…This rubber is a very mobile system, with the increased resolution afforded by HR-MAS allowing the chemical identity of cross links to be determined, and revealing that α-substitution or addition depended on the disulfide crosslinkers employed. [30,31] Other HR-MAS studies observed the impact of cross-linking in solvent swollen poly(amidoamine) polymers, the nature of water interactions in these same class of polymers, [32,33] or the cross-linking performance in silicon-containing soybean-oil copolymers. [34] HR-MAS NMR has also been used to study the functionalization of poly hydroxyethyl methacrylate (HEMA) cryogels, [35] cyclomaltoheptaose polymers, [36] the synthesis of hyper-branched bis (hydroxymethyl) propionic acid (bis-MPA) polymers as a function of catalysts, [37] and polymers for nanoparticle stabilization.…”

‘Click’ Functionalization of Cryogels Conveniently Verified and Quantified Using High‐Resolution MAS NMR Spectroscopy

“…Over the last decade, hr-MAS NMR spectroscopy has found wide spread application in biomedical NMR spectroscopy, [18] combinatorial chemistry, [19] organometallic chemistry [20] and polymer chemistry. [21,22] In this study, we evaluate the modification of polyHEMA cryogels using the copper(I)-catalyzed Huisgen azidealkyne coupling strategy (CuAAC) and show that hr-MAS NMR spectroscopy allows to validate and quantify reaction progress and completion level in a straightforward fashion. The application of various 1D 1 H hr-MAS techniques and 2D 1 H-13 C hr-MAS NMR spectroscopy for chemical characterization is reported.…”