Qiang Zhou's research while affiliated with University of Science and Technology of China and other places

Temperature‐responsive hydrogels including lower critical solution temperature (LCST)‐ and upper critical solution temperature (UCST)‐type hydrogels are attractive in various fields. However, the swift switch between LCST and UCST stimuli‐responsive behaviors remains intriguing and challenging. Here is reported a kind of hydrogel with pH‐gated LCST and UCST response behaviors. This is achieved using the hydrogen bonding between carboxylic acid groups of poly(acrylic acid‐co‐acrylamide) and hydroxyl groups of hydroxypropyl cellulose (HPC). The poly(acrylic acid‐co‐acrylamide)‐HPC (PACA‐HPC) hydrogels exhibit pH‐gated reversible LCST‐UCST phase transition behavior. When the transparent PACA‐HPC hydrogel is placed in an acid bath, the COO⁻ groups get protonated, rapidly forming hydrogen bonds with HPC to render a light‐scattering state making the hydrogel opaque. Furthermore, the opaque hydrogel exhibits UCST phase transition behavior at 20–45 °C. When the opaque PCAC‐HPC hydrogel is placed in an alkaline environment, hydrogen‐bonded complexes gradually dissociate as the COOH groups are deprotonated to form a homogeneous transparent state. The transparent hydrogel exhibits LCST phase transition behavior at 20–45° C. Therefore, is shown the hydrogen bonding strategy to fabricate hydrogels with tunable LCST and UCST responses. With this pH‐gated hydrogel with switchable LCST/UCST responsive behaviors, are demonstrated its applications in smart windows and information encryption.

Injectable self-healing hydrogels are being widely used in drug delivery, tissue engineering, and other fields. Because of their excellent biocompatibility and biodegradability, polypeptides are an ideal candidate for preparing injectable self-healing hydrogels. In this study, a polypeptide-based hydrogel with dual response to hydrogen peroxide and light was obtained by copolymerizing 4-arm PEG-amine, N-(p-nitrophenoxycarbonyl)-l-methionine, and N-(p-nitrophenoxycarbonyl)-γ-o-nitrobenzyl-l-glutamate. The hydrogel exhibits injectable self-healing behavior due to the hydrophobic interactions among peptide blocks, which also act as the reservoir of hydrophobic drug molecules. In the presence of hydrogen peroxide or under light irradiation, the thioether bond in methionine was oxidized to sulfoxide, whereas the o-nitro benzyl ester bond was broken to form glutamic acid. As a result, the corresponding hydrophobic blocks of polypeptide become hydrophilic, accelerating the release of drug molecules loaded in the polypeptide hydrophobic blocks. Using this technique, the controlled release of hydrophobic drug molecules was achieved. Our efforts could provide a new strategy for the preparation of self-healing hydrogels based on polypeptides with a dual response to hydrogen peroxide and light. In this view, the practical application of polypeptides in drug delivery, tissue engineering, and other fields, could be expanded and advanced.

A smart response fluid was designed and developed to overcome the challenges of gas channeling during CO2 flooding in low-permeability, tight oil reservoirs. The fluid is based on Gemini surfactant with self-assembly capabilities, and the tertiary amine group serves as the response component. The responsive characteristics and corresponding mechanism of the smart fluid during the interaction with CO2/oil were studied, followed by the shear characteristics of the thickened aggregates obtained by the smart fluid responding to CO2. The temperature and salt resistance of the smart fluid and the aggregates were evaluated, and their feasibility and effectiveness in sweep-controlling during the CO2 flooding were confirmed. This research reveals: (1) Thickened aggregates could be assembled since the smart fluid interacted with CO2. When the mass fraction of the smart fluid ranged from 0.05% to 2.50%, the thickening ratio changed from 9 to 246, with viscosity reaching 13 to 3100 mPa·s. As a result, the sweep efficiency in low-permeability core models could be increased in our experiments. (2) When the smart fluid (0.5% to 1.0%) was exposed to simulated oil, the oil/fluid interfacial tension decreased to the level of 1×10−2 mN/m. Furthermore, the vesicle-like micelles in the smart fluid completely transformed into spherical micelles when the fluid was exposed to simulated oil with the saturation greater than 10%. As a result, the smart fluid could maintain low oil/fluid interfacial tension, and would not be thickened after oil exposure. (3) When the smart fluid interacted with CO2, the aggregates showed self-healing properties in terms of shear-thinning, static-thickening, and structural integrity after several shear-static cycles. Therefore, this fluid is safe to be placed in deep reservoirs. (4) The long-term temperature and salt resistance of the smart fluid and thickened aggregates have been confirmed.

The development of nanosized aggregates that respond to mechanical stimuli is of great importance for applications related to ultrasound imaging or sensors, etc. In this work, we fabricate model assemblies...