Highly enhanced toughness of interpenetrating network hydrogel by incorporating poly(ethylene glycol) in first network

Abstract

An interpenetrating network (IPN) hydrogel with a highly enhanced elongation-at-break has been prepared using poly(ethylene glycol) (PEG)-swollen poly(2-acrylamide-2-methylpropane sulfonic acid) (PAMPS) as the first network and polyacrylamide (PAM) as the second network. The new IPN hydrogel of PAMPS-PEG/PAM has remarkably high elongation-at-break ($2100%) in tensile deformation, which is 4 times larger than common PAMPS/PAM IPN hydrogel and PAMPS/PAM-PEG IPN hydrogels synthesized by incorporating PEG into the second network. The microstructures of single network (SN) and IPN hydrogels were investigated by synchrotron radiation small-angle X-ray scattering (SAXS). SAXS results were analyzed by Guinier, Ornstein-Zernike (OZ), and generalized Ornstein-Zernike (GOZ) models. It was found that the incorporated PEG increases the size of cross-linked domains and decreases the fractal dimension of domains. The toughening mechanism of PEG on IPN hydrogel was discussed. It is proposed that the largely enhanced toughness of PAMPS-PEG/PAM IPN hydrogel is due to the increased size of physical cross-linked domains, hydrogen bonding between the first and second network, and the increased pull-out resistance of PAM chains under deformation.

Temperature and pH-dependent swelling and copper(ii) adsorption of poly(N-isopropylacrylamide) copolymer hydrogel

“…2D SAXS data was converted to 1D intensity I(q) as a function of the scattering vector q [q ¼ (4p/l)sin q] by circular averaging, where 2q is the scattering angle. 23,24 Temperature was controlled by a Linkam hot stage, and the sample was equilibrated at each temperature for 20 min before measurement. Fully swollen hydrogels and dehydrated hydrogels with a dimension of 10 Â 10 Â 1.0 mm 3 were used for SAXS analysis.…”

“…No noticeable scattering peaks were observed in these SAXS proles. Guinier equation 24,38 and power law 39,40 can be used to analyze the SAXS curves in the lowq range. The solid like density uctuation induced by hydrogel crosslinking can be described by Guinier equation, 24,38…”

Triple Stimuli-Responsive N-Isopropylacrylamide Copolymer toward Metal Ion Recognition and Adsorption via a Thermally Induced Sol–Gel Transition

“…2D data were converted into 1D intensity I(q) as a function of the scattering vector q [q = (4π/λ) sin θ] by circularly averaging with Fit2D software, where 2θ was the scattering angle. 26,27 3. RESULTS AND DISCUSSION 3.1.…”

“…There was no remarkable scattering peak found in these SAXS profiles. The generalized Ornstein−Zernike (GOZ) equation 26,41 was used to analyze the SAXS curves for both sols and gels:…”

Three-dimensional Layered Water-Soluble Cellulose Acetate/Polyacrylamide Composites with Ultrahigh Ductility and Stretchability

“…Therefore, there are increasing demands for reinforced-hydrogels with enhanced mechanical properties 6 . In recent years, to overcome this limitation and extend their practical applications, numerous strategies have been developed to enhance the mechanical properties, such as double network (DN) hydrogels 7 , topological (TP) gels and nanocomposite (NC) hydrogels 8 , 9 . DN hydrogels are composed of a stiff and brittle first-network and a soft and ductile second-network with the enhanced mechanical properties.…”