Highly Swellable and Stretchable Thermoresponsive Hydrogels Enabled by Functionalized Boron Nitride Nanosheets

Abstract

Thermoresponsive hydrogels with high stretchability and large swelling ratio are promising materials for fabricating soft devices, sensors, artificial muscles, etc. However, it remains a challenge to achieve these properties simultaneously within one hydrogel. Herein, highly swellable and stretchable thermoresponsive hydrogels are developed by incorporating functionalized boron nitride nanosheets (f‐BNNSs) into poly(maleic anhydride functionalized β‐cyclodextrin‐co‐N‐isopropylacrylamide) hydrogel. In such hydrogels, the dynamic host–guest interactions between f‐BNNSs and polymer matrix act as sacrificial bonds to efficiently dissipate energy, and the homogeneous covalent cross‐linking network of polymer leads to a smooth stress propagation, which enables the hydrogels to obtain excellent mechanical properties, such as remarkable strength (up to 0.15 MPa) and outstanding stretchability (up to 1457%). What is more, the resultant hydrogel also exhibits excellent thermoresponsive properties (swelling rate up to 5000% at 25 °C and deswelling rate down to 6% at 50 °C). Thus, this work offers a promising strategy to fabricate highly swellable and stretchable thermoresponsive hydrogels for potential soft actuators and bionic robotics applications.

Anti-freezing, conductive and shape memory ionic glycerol-hydrogels with synchronous sensing and actuating properties for soft robotics

“…52 2.2 Mechanical properties of the P x C y A z B w ionic glycerolhydrogels It is well known that mechanical properties are essential properties of hydrogels and signicantly affect their practicality. 53,54 Notably, the introduction of PAM and BNNS-PDMC could effectively improve the mechanical properties of the hydrogel. As shown in Fig.…”

“…It was worth noting that after adding BNNS-PDMC, the hydrogel formed a denser pore structure, which is mainly due to the interaction between BNNS-PDMC and the polymer network. 54 The crystalline properties of the hydrogel are shown in Fig. S8 (ESI†).…”

Stretchable and Thermally Responsive Semi‐Interpenetrating Nanocomposite Hydrogel for Wearable Strain Sensors and Thermal Switch

“…[ 30 ] However, compared with P(NIPAM‐ co ‐HEMA)/PNIPAM hydrogel, the parallel arrangement of the layered structure, and the compact and uniform pore size are clearly shown in the P(NIPAM‐ co ‐HEMA)/P(NIPAM‐ co ‐HEMA)/P(NIPAM‐ Au 10 @ALM 8 ) hydrogel (Figure 2c,d), owing to the abundant vinyl groups on the AuNP surfaces participated in the free radical polymerization reaction to form oriented hydrogel. [ 20 ] The XRD spectrum of sample P(NIPAM‐ co ‐HEMA)/P(NIPAM‐Au 10 @ALM 8 ) is shown in Figure , where it can be seen that they are nearly identical with a broad diffraction peak at around 2 θ = 21.1°. This broad fundamental diffraction peak indicates the amorphous structure of the P(NIPAM‐ co ‐HEMA)/P(NIPAM‐Au 10 @ALM 8 ) sample (poor crystallinity).…”

“…Multifunctional crosslinking agents composed of Au nanoparticles (AuNPs) and vinyl‐containing organic molecules densely absorbed on the surface through Au‐S interaction were prepared. [ 19–20 ] Allyl mercaptan (ALM), [ 21 ] as a kind of ω ‐alkene‐l‐thiols, undergo typical reactions for both aliphatic thiols and olefins. The aliphatic thiols can act as surface stabilizing reagents in the formation of nanoparticles and the C═C bond can participate in the free radical polymerization reaction.…”

Boron Nitride Nanosheets Strengthened PVA/Borax Hydrogels with Highly Efficient Self‐Healing and Rapid pH‐Driven Shape Memory Effect

“…The PVA/BNNS‐NH 2 composite hydrogel showed rapid shape memory effect driven by pH value which enabled to memorize the initial shape and recover to the original shape with external stimulus after changing the shape. [ 42 ] As shown in Figure , the hydrogel can be put into the acidic solution to soften the hydrogel with the breakage of partial dynamic borate bonds. The softened hydrogel was bended to the semicircle and immersing in alkaline solution with the pH value of 11 for a few minutes leading to the refounded of the dynamic borate bonds obtained the hydrogel with the temporary shape of semicircle.…”