A Novel Temperature‐Dependent Hydrogel Emulsion with Sol/Gel Reversible Phase Transition Behavior Based on Polystyrene‐co‐poly(N‐isopropylacrylamide)/Poly(N‐isopropylacrylamide) Core–Shell Nanoparticle

Abstract

As a kind of temperature‐responsive hydrogel, polystyrene‐co‐poly(N‐isopropylacrylamide)/poly(N‐isopropylacrylamide) (PS‐co‐PNIPAM/PNIPAM) core–shell nanoparticles prepared by two‐step copolymerization are widely studied and used because of their specific structures and properties. Unlike most reports about the steady stability of PS‐co‐PNIPAM/PNIPAM core–shell nanoparticle hydrogel emulsion, in this work, the PS‐co‐PNIPAM/PNIPAM core–shell nanoparticle hydrogel emulsion (symbolized as PS/PNIPAM hydrogel emulsion), which is prepared after the second step of synthesis and without washing out a large number of PNIPAM polymer segments, shows a reversible temperature‐dependent sol–gel transition characteristic during the temperature range of 34–80 °C. The PS/PNIPAM hydrogel emulsion is a normal solution at room temperature, and it changes from a sol to a gel statue when the temperature approaches up to low critical solution temperature (LCST). As the temperature continues to increase, the gel (core–shell nanoparticles as the crosslinkers and the linear PNIPAM chain as the 3D gel network) of the PS/PNIPAM hydrogel emulsion gradually shrinks and drains linearly. Compared with most crosslinked hydrogels, the hydrogel here can be arbitrarily changed in shape according to use needs, which is convenient for use, transportation, and storage. Here a new route is provided for the preparation of a PS/PNIPAM core–shell hydrogel nanoparticle system, as well as a new supramolecular crosslinking sol–gel system for application in biomedical materials, sensors, biological separation, drug release, macromolecular adsorption, and purification.

A New Reversible Thermosensitive Liquid–Solid TENG Based on a P(NIPAM‐MMA) Copolymer for Triboelectricity Regulation and Temperature Monitoring

“…When the temperature is lower than the LCST, more hydrophilic amide groups are exposed at the solid–liquid interface, thus causing more hydrophilicity, and when the temperature is higher than the LCST, more hydrophobic isopropyl groups are exposed at the solid–liquid interface, resulting in more hydrophilicity with a larger contact angle. [ 38 ] As shown in Figure 1c, the water CA on PNM surface at 20 °C is 22.49° and increases to 82.08° at 60 °C. Theoretically, the hydrophobic surface facilitates rapid separation from water and is conducive to the accumulation of triboelectric charges on the PNM surface.…”

Investigation of the Release Mechanism and Mould Resistance of Citral-Loaded Bamboo Strips

“…Therefore, an increase in the concentration of P/Cn could significantly improve R 2 . However, considering that high concentration can easily cause gel precipitation that makes it difficult to impregnate bamboo [ 32 , 33 ], the value of 1.0 was eventually determined as the optimal CR. In other words, the original concentration of P/Cn8 was selected for bamboo strip processing.…”

Novel Hydrogels Based on the Nano-Emulsion Formulation Process: Development, Rheological Characterization, and Study as a Drug Delivery System

“…This ternary system is, by definition, a bi-continuous mixture of oil and water phases with specific rheological properties of hydrogels and is a prime candidate for hybrid drug delivery. In contrast, literature reports have described hybrid hydrogels made with the gelation of emulsions already produced [ 2 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 ] are indeed different from nanoemulgel concept because these examples need the addition of polymers to create a networking matrix in the aqueous phase.…”