Study on a new polymer/graphene oxide/clay double network hydrogel with improved response rate and mechanical properties

Abstract

pH‐ and temperature‐responsive double network hydrogels (DN hydrogels) were prepared by using poly (N‐isopropylacrylamide) (PNIPAM) as a tightly crosslinked network (1st network), polyacrylic acid (PAA) as a loosely crosslinked network (2nd network), with clay and graphene oxide as effective crosslinkers and reinforcing fillers. The structure and morphology of the hydrogels were characterized by SEM, FTIR, DSC, and TGA. The synergetic effects of clay, GO and DN structure on various physical properties were investigated. With the increasing of crosslinking densities, the swelling ratios of DN hydrogels gradually decreased by increasing the contents of graphene oxide and PAA. While the DN hydrogels had much better mechanical properties than that of the conventional chemically cross‐linked PNIPAM hydrogels. POLYM. ENG. SCI., 55:1361–1366, 2015. © 2015 Society of Plastics Engineers

Extremely Compressible Hydrogel via Incorporation of Modified Graphitic Carbon Nitride

“…Swelling in water is an important property of hydrogels. Usually, addition of reinforcer (such as clay) decreases water uptake due to increased crosslinking density and hydrophobic interactions . Hence, it is a challenging task to improve mechanical and preserve swelling properties of hydrogels simultaneously.…”

“…Usually, addition of reinforcer (such as clay) decreases water uptake due to increased crosslinking density and hydrophobic interactions. [41] Hence, it is a challenging task to improve mechanical and preserve swelling properties of hydrogels simultaneously. For the swelling properties, interestingly 2 wt% g-CN-AHPA showed the highest swelling ratio with 2476%, yet still showing a similar rheology profile and compressibility to the one right after gelation (Figure 3a).…”

Robust hydrogel of regenerated cellulose by chemical crosslinking coupled with polyacrylamide network

“…Simultaneously, the ESR of the RC/PAAm DN hydrogels decreased from 1332 to 703% by increasing the AAm concentration from 1 to 5 mol L −1 . It is well known that the swelling properties of hydrogels mainly depend on the effective crosslinking density of the hydrogels . The RC/PAAm DN hydrogels with higher PAAm content lead to more densely crosslinked networks, thus decreasing the SRs of the hydrogels.…”

“…It is well known that the swelling properties of hydrogels mainly depend on the effective crosslinking density of the hydrogels. 57 The RC/PAAm DN hydrogels with higher PAAm content lead to more densely crosslinked networks, thus decreasing the SRs of the hydrogels. However, while ECH:GU increases from 1:1 to 5:1, the SR increased from 478 to 703%.…”

Graphene derivatives in responsive hydrogels: Effect of concentration and surface chemistry

“…In all cases the shrinkage of the nanocomposite gel disks was less than that of the pure PNIPA gel after 1000 minutes, but the difference, as well as the shape of the shrinkage curves were different for the different systems. In cases where strong interaction is presumed between the CNPs and the polymer matrix (GO@PNIPA and (GO@PNIPA)R) the slower response may be explained by the decrease of the free volume inside the nanocomposite matrix [35,45] that is caused by the increasingly hypernode-like structure. The prolonged shrinkage of the samples suggests a complex process involving the deswelling of the gel matrix, the realignment of the CNP particles and the relaxation of the polymer chains [35,36].…”