Structure and dynamics of hydrogels and organogels: An NMR spectroscopy approach

• Published in: Progress in polymer science Vol. 36; no. 9; pp. 1184 - 1253
• Main Author: Shapiro, Yury E.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01-09-2011; Elsevier
• Subjects: Applied sciences; Constituents; Dynamical systems; Dynamics; Exact sciences and technology; Hydrogels; Morphology; Morphology and mobility; Network structure; NMR spectroscopy; Nuclear magnetic resonance; Organic polymers; Organogels; Physicochemistry of polymers; Properties and characterization; Semi-solid processing; Solution and gel properties; Network structure; Organogels; Hydrogels; Morphology and mobility; NMR spectroscopy; Gelation; Polymer; NMR spectrometry; Review; Intramolecular mobility; Mechanism; Organic solution; Hydrogel; Aqueous solution; Lattice structure
• ISSN: 0079-6700; 1873-1619
• DOI: 10.1016/j.progpolymsci.2011.04.002

► Hydro-/organogels are semi-solid systems, with a liquid phase immobilized within a 3D network composed of self-assembled, intertwined polymer/gelator. ► NMR techniques allow obtaining the detailed information on morphology, molecular organization, specific interactions and internal mobility of the gel constituents. ► This review aims at providing a global view and capabilities of NMR in comprehensive studies of hydrogels and organogels.
Hydrogels and organogels are semi-solid systems, in which a liquid phase is immobilized by a three-dimensional network composed of self-assembled, intertwined polymer/gelator fibers. Investigations pertaining to these systems have only picked up speed in the last few decades. Consequently, many burning questions regarding these systems, such as the specific molecular requirements guaranteeing gelation, still await definite answers. Nonetheless, the application of different hydrogels and organogels to various areas of interest, i.e., as drug delivery devices, has been quick to follow their discoveries.
The use of NMR spectroscopy for the characterization of polymer hydrogels and organogels has recently seen enormous growth. The NMR measurements involving magic angle spinning (MAS) in the solid-state NMR, spin relaxation times, nuclear Overhauser enhancements (NOE), or multiple-quantum (MQ) spectroscopy, the pulse field gradient (PFG) technique and magnetic resonance imaging (MRI) allow obtaining the detailed information on morphology, molecular organization, specific interactions and internal mobility of constituents.
This review aims at providing a global view and capabilities all of these NMR methods in comprehensive studies of hydrogels and organogels, with special emphasis on the interplay between the morphology and molecular mobility of constituents and the intermolecular interactions.