Polymer Networks Synthesized from Poly(Sorbitol Adipate) and Functionalized Poly(Ethylene Glycol)

Abstract

Polymer networks were prepared by Steglich esterification using poly(sorbitol adipate) (PSA) and poly(sorbitol adipate)-graft-poly(ethylene glycol) mono methyl ether (PSA-g-mPEG12) copolymer. Utilizing multi-hydroxyl functionalities of PSA, poly(ethylene glycol) (PEG) was first grafted onto a PSA backbone. Then the cross-linking of PSA or PSA-g-mPEG12 was carried out with disuccinyl PEG of different molar masses (Suc-PEGn-Suc). Polymers were characterized through nuclear magnetic resonance (NMR) spectroscopy, gel permeation chromatography (GPC), and differential scanning calorimetry (DSC). The degree of swelling of networks was investigated through water (D2O) uptake studies, while for detailed examination of their structural dynamics, networks were studied using 13C magic angle spinning NMR (13C MAS NMR) spectroscopy, 1H double quantum NMR (1H DQ NMR) spectroscopy, and 1H pulsed field gradient NMR (1H PFG NMR) spectroscopy. These solid state NMR results revealed that the networks were composed of a two component structure, having different dipolar coupling constants. The diffusion of solvent molecules depended on the degree of swelling that was imparted to the network by the varying chain length of the PEG based cross-linking agent.

Small Oligonucleotides Detection in Three-Dimensional Polymer Network of DNA-PEG Hydrogels

“…The advantage of this analysis is that it works in the absence of concentration gradients, studying instead the chaotic motion of molecules driven by intermolecular collisions [ 32 ]. Diffusion times over a large range, usually from a few milliseconds up to seconds, are available via PFG-NMR techniques and can be chosen arbitrarily by selecting the correct attenuation parameters [ 44 ]. The study of the probe diffusion on these short timescales, allows for obtaining much information on the microscopic structure of materials [ 32 , 42 , 43 , 44 , 45 , 47 ].…”

“…Diffusion times over a large range, usually from a few milliseconds up to seconds, are available via PFG-NMR techniques and can be chosen arbitrarily by selecting the correct attenuation parameters [ 44 ]. The study of the probe diffusion on these short timescales, allows for obtaining much information on the microscopic structure of materials [ 32 , 42 , 43 , 44 , 45 , 47 ]. In particular, we are interested in measuring the water self-diffusion coefficient (D) that is directly related to the potential for water to leave a hydrogel [ 46 , 48 , 49 , 50 ].…”

“…In the absence of any specific interactions between the probe and the network, the diffusivity of the probe reflects the network structure [ 29 , 30 , 31 ]. Common techniques used to study probe diffusion include source–sink techniques [ 32 ], fluorescence recovery after photobleaching (FRAP) [ 34 , 37 ], FCS [ 38 , 39 , 40 ] and pulsed field gradient NMR (PFG-NMR) [ 32 , 35 , 41 , 42 , 43 , 44 , 45 ]. The key for PFG-NMR analysis is the fact that NMR data render information on the chemical nature, as well as on the molecular mobility, of an observed component.…”

Physico‐mechanical properties of poly(ethylene glycol)‐based polymer networks

“…The physical properties of cross‐linked polymers are strongly dependent on the chemical structure and homogeneity of the network 7 . Previously, different methods have been used to synthesize polymer networks 3,8–12 . However, these synthetic methods have some limitations, such as side reactions, uncontrolled reaction rates, and incomplete conversion which results in poorly defined networks with several defects, such as dangling chain ends, loops of different order, and entanglements.…”

“…7 Previously, different methods have been used to synthesize polymer networks. 3,[8][9][10][11][12] However, these synthetic methods have some limitations, such as side reactions, uncontrolled reaction rates, and incomplete conversion which results in poorly defined networks with several defects, such as dangling chain ends, loops of different order, and entanglements. These kinds of defects certainly affect the mechanical and other properties of polymer networks.…”