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Microgel suspensions have garnered significant interest in fundamental research due to their phase transition between liquid-like to paste-like behaviors stemming from tunable interparticle and particle-solvent interactions. Particularly, stimuli-responsive microgels undergo faster volume changes in response to external stimuli in comparison to their bulk counterparts, while maintaining their structural integrity. Here, concentrated and diluted suspensions of poly(N-isopropylacrylamide) (PNIPAm) microgels are dispersed to different packing fractions in water for the characterizations of temperature-responsive rheological responses. In the intrinsic volume phase transition (VPT), polymer chains collapse, and microgels shrink to smaller sizes. Additionally, the intermicrogel and microgel-solvent interactions vary in VPT, which results in microgel clusters that significantly affect the linear shear moduli of suspensions. The effect of the temperature ramp rate of PNIPAm microgel suspensions on rheological responses is characterized. Moreover, the effect of the mass fraction of microgels on the relative viscosity of dilute microgel suspensions is investigated. These results shed light on understanding the heating and cooling rate-dependent temperature responsiveness of PNIPAm microgel suspensions, establishing pathways to regulate the rheological characteristics in temperature-responsive microgel-based platforms. Therefore, this work envisions technological advancements in different fields such as drug delivery, tissue engineering, and diagnostic tools.

Hydrogels, composed of hydrophilic homopolymer or copolymer networks, have structures similar to natural living tissues, making them ideal for applications in drug delivery, tissue engineering, and biosensors. Since Wichterle and Lim first synthesized hydrogels in 1960, extensive research has led to various types with unique features. Responsive hydrogels, which undergo reversible structural changes when exposed to stimuli like temperature, pH, or specific molecules, are particularly promising. Temperature-sensitive hydrogels, which mimic biological processes, are the most studied, with poly(N-isopropylacrylamide) (PNIPAm) being prominent due to its lower critical solution temperature of around 32 °C. Additionally, pH-responsive hydrogels, composed of polyelectrolytes, change their structure in response to pH variations. Despite their potential, conventional hydrogels often lack mechanical strength. The double-network (DN) hydrogel approach, introduced by Gong in 2003, significantly enhanced mechanical properties, leading to innovations like shape-deformable DN hydrogels, organic/inorganic composites, and flexible display devices. These advancements highlight the potential of hydrogels in diverse fields requiring precise and adaptable material performance. In this review, we focus on advancements in the field of responsive acrylamide-based hydrogels with IPN structures, emphasizing the recent research on DN hydrogels. [ABSTRACT FROM AUTHOR]

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Microcapsules are small particles that can effectively protect a core material from degradation. Microcapsules with double capsule walls can improve stability and reduce breakage due to the fact that the physical and chemical properties of double-walled materials can complement each other, thus enhancing the quality and applicability of a microcapsule. Microcapsules can achieve controlled release of core materials by using a temperature-sensitive wall material. In this research, gelatin was used as the inner wall material for these double-walled microcapsules. The outer wall material was a composite material prepared by the reaction of a hydroxyl group in gum arabic with an amino group in N-isopropylacrylamide (NIPAM) in the presence of N, N'-methylene bisacrylamide (BIS), while lavender fragrance oil served as the core material. A complex coalescence method was used for the preparation of microcapsules with double capsule walls. The effects of different proportions of gum arabic to NIPAM on the core loading, microcapsule yield and thermal stability of microcapsules were studied in detail. Additionally, the stability of these fragrance microcapsules with double capsule walls in different solvents and pH values was evaluated. The sustained release properties and mechanism of cotton fabrics treated with prepared fragrance microcapsules were investigated. The results show that the microcapsules prepared with a 10:1 ratio of NIPAM to gum arabic have good temperature responsiveness. Therefore, clothing treated with microcapsules with temperature-sensitive wall materials can ensure that the human body has a fresh and pleasant smell in the case of perspiring in summer. [ABSTRACT FROM AUTHOR]

In recent years, the coupling of structurally and functionally controllable polymers with biologically active protein materials to obtain polymer–protein conjugates with excellent overall properties and good biocompatibility has been important research in the field of polymers. In this study, the hyperbranched polymer hP(DEGMA-co-OEGMA) was first prepared by combining self-condensation vinyl polymerization (SCVP) with photo-induced metal-free atom transfer radical polymerization (ATRP), with 2-(2-bromo-2-methylpropanoyloxy) ethyl methacrylate (BMA) as inimer, and Di (ethylene glycol) methyl ether methacrylate (DEGMA) and (oligoethylene glycol) methacrylate (OEGMA, Mn = 300) as the copolymer monomer. Then, hP(DEGMA-co-OEGMA) was used as a macroinitiator to continue the polymerization of a segment of pyridyl disulfide ethyl methacrylate (DSMA) monomer to obtain the hyperbranched multiarm copolymers hP(DEGMA-co-OEGMA)-star-PDSMA. Finally, the lysozyme with sulfhydryl groups was affixed to the hyperbranched multiarm copolymers by the exchange reaction between sulfhydryl groups and disulfide bonds to obtain the copolymer protein conjugates hP(DEGMA-co-OEGMA)-star-PLZ. Three hyperbranched multiarm copolymers with relatively close molecular weights but different degrees of branching were prepared, and all three conjugates could self-assemble to form nanoscale vesicle assemblies with narrow dispersion. The biological activity and secondary structure of lysozyme on the assemblies remained essentially unchanged. [ABSTRACT FROM AUTHOR]

The ultrafast preparation of electrically conductive hydrogels to endow high sensing performance and temperature tolerance remains a critical challenge. Herein, lignosulfonate sodium-templated polypyrrole (LS-PPy) nanofillers were rapidly introduced into polyacrylic acid (PAA) hydrogel through ultrafast free radical polymerization in a glycerol/water binary solvent system. The resultant LS-PPy/PAA electrically conductive organohydrogel possesses satisfactory mechanical performance (strength of 56 kPa at a tensile strain of 800 %), strong adhesion, and a desirable low freezing point (−35 °C). Furthermore, this organohydrogel exhibits high strain sensitivity (gauge factor = 2.65), fast response time (∼160 ms), low signal hysteresis, and excellent cyclic stability (over 1200 cycles). And the wearable LS-PPy/PAA organohydrogel sensor could accurately and real-time monitor various intense or subtle human movements, such as joint bending, facial expression and hand writing. Besides, the developed LS-PPy/PAA temperature sensor can respond to environmental temperature variations over a wide range of −20–100 °C. High resolution of 0.5 °C with remarkable sensitivity (−0.80 %/°C and linearity of R2 = 0.99) and repeatability were achieved within 36.5–40 °C, which makes it suitable for human body temperature monitoring. All these results demonstrate the substantial prospective value of the LS-PPy/PAA hydrogel in wearable sensors and other associated fields. [ABSTRACT FROM AUTHOR]

A supramolecular gel temporary plugging agent suitable for use in shale gas reservoirs of 90-110 ℃ was developed based on the principle of supramolecule chemistry. It has several advantages such as adjustable stable time, high strengths and ease of being removed. These advantages make it suitable for temporarily plugging micro-fractures and deep fractures.The new temperature-responsive supramolecular gel temporary plugging agent SCD12 was developed with β-CD as the host and SES as the guest, as well as other additives. Characterization of SCD12 shows that there is a supramolecular action among different components of the plugging agent. SCD12 was tested for the weight of residue after gel breaking, compatibility, rheology and temporary plugging performance. These experiments show that SCD12 is in a liquid form in room temperature and has low viscosity and hence good pumpability. At elevated temperatures, SCD12 can quickly plug fractures. SCD12 can effectively plug fractures in a certain temperature range even after gel breaking which results in viscosity reduction. The dynamic plugging capacity of SCD12 is 168.06 MPa·m-1. Percent permeability loss of a rock sample by SCD12 is 9.3%. These advantages of SCD12 satisfy the needs of temporary plugging in diverting fracturing of shale gas reservoirs, and make SCD12 a new promising temporary plugging agent. [ABSTRACT FROM AUTHOR]

Textiles with heat management have good effects on improving comfort during sports. However, it is still a great challenge to endow textiles with responsiveness to external environmental changes. Herein, we developed a temperature-regulating cotton textile with multiple heat transfer capabilities by a two-step method. Firstly, hydroxylated boron nitride (BN-OH) nanosheet dispersion liquid was prepared using the ultrasonic-alkali treatment. Subsequently, enzymatic graft polymerization of N-isopropyl acrylamide (NIPAM) onto cotton fibers was performed using horseradish peroxidase. The composite cotton fabric, containing entrapped BN-OH, exhibits unique temperature-regulating ability. The thermal diffusivities in lateral and in-plane directions reach 1.3 and 1.7 times of the untreated, respectively. This can be attributed to the temperature responsiveness of poly-NIPAM (PNIPAM) and the increase in the packing density of the thermally conductive nanosheets at high temperatures. Meanwhile, the PNIPAM covering the fiber surfaces expands at low temperatures, accordingly minishes the gap sizes between fabric yarns and endows the fabric with improved heat preservation effects. The present work provides an enzyme-mediated strategy for developing textiles with ambient temperature self-response ability. [ABSTRACT FROM AUTHOR]

Energy-saving smart windows could reduce building energy consumption by dynamically regulating solar transmission without consuming additional energy. However, current thermochromic smart windows based on hydroxypropyl cellulose (HPC) are still facing challenges, such as low durability and unsatisfactory in regulating the solar infrared region. To expand hydrogels' modulation ability of infrared region, hydrogels with temperature-sensitive properties of polyvinyl alcohol (PVA) and HPC were prepared and applied in thermochromic smart windows areal. The HPC-PVA hydrogels have an ultra-high luminous transmission in the visible light rather than infrared light regions, blocking most of the sunlight when the temperature increases, thus greatly enhancing the solar modulating ability (∆Tsol) and infrared transmittance modulation (∆TIR). The 4 wt.% PVA doped in HPC exhibits the best solar modulation ability (∆TIR, (20–50 °C) 5.5%, ΔTsol, (20–50 °C) 19.4% and Tlum, 20 °C 91.3%). In addition, these high-performance and temperature-sensitive materials have a high repetition and durability. The hydrogels could obtain adjusting broadband sunlight smart windows with sandwich structure glasses. Hybrid thermochromic hydrogels HPC-PVA were designed by one-step hydrothermal method categories. The hydrogels could increase the temperature-responsive of smart hydrogels, enhance solar modulation and have high luminous transmission. [ABSTRACT FROM AUTHOR]

The preparation of cells is a critical step in cell therapy. To ensure the effectiveness of cells used for clinical treatments, it is essential to harvest adherent cells from the culture media in a way that preserves their high viability and full functionality. In this study, we developed temperature-responsive poly(N-isopropylacrylamide) (PNIPAM)-grafted polystyrene (PS) microspheres using reversible addition-fragmentation chain transfer polymerization. These microspheres allow for the non-destructive harvesting of cultured cells through temperature changes. The composition and physicochemical properties of the PNIPAM-grafted PS microspheres were confirmed using infrared spectroscopy, elemental analysis, dynamic light scattering, and thermogravimetric analysis. In vitro experiments demonstrated that these microspheres exhibit excellent biocompatibility, supporting the adhesion and proliferation of various cells. Moreover, the microspheres showed good temperature responsiveness in thermosensitive detachment experiments with GFP-HepG 2 cells and umbilical cord mesenchymal stem cells (UC-MSCs). Additionally, through orthogonal experiments, we identified a cell detachment aid mixture that significantly improved the dispersibility of cells detached from the microspheres, enhancing the efficiency of thermosensitive cell detachment by approximately 40%. The harvested UC-MSCs retained their capacity for re-proliferation and trilineage differentiation. Consequently, the temperature-responsive microspheres developed in this study, combined with the cell detachment aid mixtures, hold great potential for large-scale culture and harvesting of therapeutic cells in clinical applications., (© 2024 IOP Publishing Ltd. All rights, including for text and data mining, AI training, and similar technologies, are reserved.)

The hereditary basis and identification of novel genes of heading date have significant implications for japonica rice improvement in northeast China, especially in Heilongjiang province. A re‐sequenced recombinant inbred line (RIL) population derived from the cross between Lijiangxintuanheigu (LTH) and Shennong 265 (SN265) was used to detect the genetic basis for the RIL in 2017 and 2018. Fourteen heading date quantitative trait loci (QTLs), including nine in 2017 and thirteen in 2018, were detected with a linkage map containing 2,818 bin markers. They were distributed on chromosomes 3, 4, 6 and 9–11 with 9.34%–25.26% phenotypic variations. The QTLs qHD3a, qHD4a, qHD4b, qHD4c, qHD9b, qHD10, qHD11c and qHD11d were identified in both years. The qTRS1, qTRS3a (qHD3a), qTRS3b (qHD3b) and qTRS9 (qHD9a) alleles from LTH and the qTRS4 allele from SN265 were identified by controlling the temperature responsiveness in the RIL population. The explained phenotypic variation in these five QTLs varied from 14.52% to 26.31%. In order to accurately determine the difference in heading date under different temperature conditions, the RILs and two parents were grown in a phytotron. Four QTLs controlling temperature responsiveness were identified on chromosomes 3, 6 and 9, including qTRS3a (qHD3a), qTRS3b (qHD3b), qTRS6 and qTRS9 (qHD9a). In a different environment, qTRS3a (qHD3a), qTRS3b (qHD3b) and qTRS9 (qHD9a) were detected. A comparison of chromosomal locations between the QTLs detected in this study and heading date genes previously cloned indicated that DTH3, Hd16, RFL, HAF1, Ehd2 and RBS1 might be candidate genes for them. The four major heading date genes (Hd1, Ghd7, Ghd7.1 and Ghd8) affecting ecogeographical adaptation were sequenced between SN265 and LTH. SN265 carried a functional Hd1 haplotype, a weak functional Ghd7 haplotype, a weak functional Ghd7.1 haplotype and a weak functional Ghd8 haplotype. LTH also carried functional Hd1 haplotype, a weak functional Ghd7 haplotype, a non‐functional Ghd7.1 haplotype and a non‐functional Ghd8 haplotype. The combinations of the Hd1, Ghd7, Ghd7.1 and Ghd8 alleles in SN265 and LTH largely defined their short heading date under long‐day conditions. The selection of heading date gene combinations with functional Hd1 alleles and non‐functional alleles or weak functional alleles of Ghd7, Ghd7.1 and Ghd8 would be an effective way to improve japonica rice with proper heading days in Northeast China. The novel QTLs detected in this study could also become a valuable source for designing the appropriate heading date in Northeast China japonica rice. [ABSTRACT FROM AUTHOR]

Cholesteric liquid crystal oligomers and polymers are promising materials for creating materials and devices with stimuli-responsive structural color, and the cholesteric to smectic pre-transition effect is of particular interest as it leads to a strong redshift in the reflected color upon cooling. Cholesteric polymers can be stabilized by the formation of semi-interpenetrating networks to obtain more robust photonic materials, but this tends to strongly suppress the pre-transition effect. Here, we show that the pre-transition effect in semi-interpenetrating networks based on main-chain cholesteric oligomers can be amplified by incorporating a smectic monomer and by increasing the degree of polymerization of the oligomers. This amplification counteracts the suppressing effect of the semi-interpenetrating network, and the resulting materials still show a significant band shift upon cooling. Presumably, both methods lead to the formation of more smectic domains in the cholesteric helix, which causes an amplified pre-transitional effect. The results bring us closer to the use of cholesteric semi-interpenetrating cholesteric networks for applications in smart sensing, healthcare, and safety devices.

Summary: Halogen bonding (XB) opens avenues to supramolecular assemblies. Here, we report XB-driven supramolecular assemblies of quaternary ammonium iodide (QAI)-containing polymers in three (solution, surface, and solid) phases. In the solution, QAI-containing block copolymers form unique self-assembly structures such as micrometer-sized giant vesicles (up to 5-μm diameter) and a 1-dimensional (1D) structure with multiple inter-vesicular linkages via XB. Exploiting the temperature dependence of XB strength, external molecules are successfully loaded and unloaded. On the surface, reversible XB crosslinking and decrosslinking of QAI-containing polymer brushes are achieved. The wettability of the polymer brush is finely tuned by the XB crosslinking density. In solid phase, QAI-containing monomers are co-crystalized (assembled) via XB. A polymer sheet is obtained via the solid-phase polymerization of the monomer co-crystal; the sheet enables capture and release of halogen-containing (XB-coordinating) guest molecules and thereby serves as an innovative host material.

Smart materials that can respond to external stimuli are typically prepared through the coating of specific responsive ligands. Herein, for the first time, thermally reconfigurable single polyoxometalate (POM) cluster assemblies without temperature‐responsive surfactants are reported. Based on transmission electron microscopy observation, POM clusters are obtained to arrange into a 2D single cluster superlattice at 25 °C, and transform themselves into a single cluster nanowire below 0 °C, which is caused by the switching of hydrogen bond linkage between clusters. Contributed by the specific coordinative state, the POM assembly exhibits excellent catalytic activity and stability toward olefin epoxidation at room temperature, demonstrating the application potentials of the nanostructures based on single clusters. [ABSTRACT FROM AUTHOR]

Light-responsive microgels are interesting colloidal systems with potential applications in the biotechnology and medicine. However, synthesis of light-responsive microgels with high loading of photoswitchable molecules is still very challenging. Herein we developed a new method to synthesize light and temperature dual-responsive spiropyran-modified poly(N -vinylcaprolactam) microgels. The novel and straightforward microgels synthesis route involved: a) synthesis of poly(N -vinylcaprolactam- co -vinylformamide) copolymers via RAFT polymerization followed by the hydrolysis to obtain primary amine groups, b) attachment of carboxyl-modified spiropyran molecules to polymer chains via coupling, and c) crosslinking of spiropyran-modified polymer chains in W/O miniemulsion to form microgels. Via this method, we successfully synthesized poly(N -vinylcaprolactam) microgels containing more than 10 mol% spiropyran. The reversible light responsiveness of the spiropyran-modified copolymers and microgels in aqueous solution, which originates from the spiropyran photoisomerization under irradiation with different wavelengths, was demonstrated by UV–Vis spectroscopy. Spiropyran-modified copolymers demonstrate shift of the lower critical solution temperature (LCST) due to the polarity change of spiropyran molecules under dark, UV and visible light. Surprisingly, dynamic light scattering (DLS) results show that the microgels based on the same copolymers are less affected by UV irradiation. Microgels are swollen in darkness when spiropyran molecules are in the polar, merocyanine form, and collapse after irradiation with visible light, due to the transformation of spiropyran to the relatively nonpolar, closed spirocyclic form. In addition, the spiropyran-modified microgels exhibit reversible temperature responsiveness by presenting a volume phase transition in water from a swollen state to a collapsed state with increasing temperature and the transition temperature decreased compared to the pristine microgels due to the hydrophobicity of spiropyran units. [ABSTRACT FROM AUTHOR]

A softer natural Pickering nanostabilizer, S -ovalbumin (S -OVA) was reported in this work, based on our previous researches about soft globular protein nanoparticles. Compared with native OVA, S -OVA has higher surface hydrophobicity, greater conformational flexibility and thinner tightly-bond water layer, which make it be unfolded more highly at the oil–water interface. However, S -OVA also possesses higher zeta-potential and thicker closely-surrounding water layer, offering it stronger electrostatic repulsion and steric hindrance between molecules and increased intramolecular cohesion. The improvements guarantee S -OVA undisintegrated particle structure and independent state on the interface and high refolding off the interface. The more flexible interior and firmer exterior together endow a higher softness to S -OVA. The HIPPE gels solely stabilized by S -OVA were fabricated using one-step shearing. These HIPPE gels own steady network structure mainly supported by bridging flocculation, strong self-supporting ability and moldability. The high storage stability and ability to inhibiting lipid oxidization provide the HIPPE gels an enormous potential in encapsulating and protecting volatile, easily-oxidized or dangerous organic liquids, during the storage and transportation. The attractive temperature responsiveness offers a high convenience to re-obtaining the organic liquids. And a re-encapsulation can be easily achieved via a re-shearing. The heat-enhanced gel intensity and moldability mean the HIPPE gels can be applied to produce dualistic gels or porous scaffolds with latent applications. These findings are helpful to explore more new Pickering stabilizers from the nature and extend the applications of HIPPEs in highly-demanded and high-tech industries. [ABSTRACT FROM AUTHOR]

Based on a facile and universal method using noncovalent bonding, here, polymer‐modified covalent organic framework materials (COFs) were rapidly prepared. PNIPAM‐modified COF (COF‐PNIPAM) was synthesized by electrostatic self‐assembly between COF prepared by low‐cost melamine and terephthalaldehyde and carboxyl‐terminated poly(N‐isopropylacrylamide) (PNIPAM) prepared via reversible addition‐fragmentation chain transfer polymerization. The carboxyl‐terminated PNIPAM was characterized by Gel Permeation Chromatography and Ultraviolet and Visible Spectroscopy (UV–vis). COF and COF‐PNIPAM were characterized by Fourier Transform Infrared Spectroscopes, Scanning Electron Microscope, Transmission Electron Microscope, X‐Ray Diffractomer (XRD), and Brunner‐Emmet‐Teller (BET) measurements. The results showed that the COF‐PNIPAM was successfully prepared. The Pickering emulsion properties of the COF‐PNIPAM in a water‐to‐toluene mixed system were studied, and when the water‐to‐oil ratio is 2:1, a stable emulsion can be obtained. However, the results show that the PNIPAM chains of COF‐PNIPAM nearly lose their temperature responsiveness. [ABSTRACT FROM AUTHOR]

The goal of this work was to synthesize hybrid thin films prepared combining polyamide-6 (N6) and microcellulose (CE) at various weight ratios. Products exhibited improved mechanical properties, temperature-tunable hydrophilicity, and antimicrobial features. The obtained N6@CE films were grafted with N-vinylcaprolactam (NVCL) using gamma-rays, providing temperature responsiveness in a range of 37–38 °C. The grafting degree was studied as a function of CE percentage on the film, monomer concentration, and absorbed dose. The grafting degree increased with the percentage of CE on the film, and the maximum grafting was achieved at monomer concentration and the irradiation dose of 20% NVCL and 20 kGy, respectively. NVCL grafting was confirmed by SEM, 13C-CPMAS NMR, FTIR-ATR, and XPS. SEM images attested formation of nanopores on the structure, caused by the grafting process, that consequently triggering on the new characteristics of the final materials. Potential performance of the composites as wound dressings was investigated in terms of their capability to loading and release of antimicrobial agents, such as vancomycin and benzalkonium chloride. NVCL grafting enhanced the uptake of both drugs, especially benzalkonium chloride, and regulated their release demonstrating antimicrobial effectiveness against Staphylococcus aureus. [ABSTRACT FROM AUTHOR]

A series of thermo-responsive core cross-linked star polymers (CCSP), in which poly(methoxypolyethylene glycol-co-di(ethylene glycol) ethyl ether acrylate) (P(PEGA-co-DEGA)) served as the thermo-responsive arm, have been successfully prepared via reversible addition-fragmentation chain transfer (RAFT) polymerization using the “arm-first ” approach. Fourier transform infrared spectroscopy (FT-IR) and nuclear magnetic resonance spectroscopy (1H-NMR) have been applied to characterize the structure and composition of the resultant polymers. The molecular weight of the P(PEGAco- DEGA) arm and the corresponding CCSP were obtained by gel permeation chromatography (GPC) analysis, which showed that the efflux time of CCSP was significantly shortened compared with its corresponding arm, indicating that the CCSP was successfully prepared. The phase transition behavior of the resultant CCSP was evaluated by UV-Vis spectroscopy. Results showed that the low critical solution temperature (LCST) of CCSP displayed a downward trend with increasing the content of DEGA in the P(PEGA-co-DEGA) arm. The LCST of CCSP was also influenced by the pH value of the solution due to the ionization of the carboxylic acid groups at the end of the polymer chains, leading to an upward trend with the increase of pH value. The experimental results indicated that the LCST of CCSP could be controlled in the range of 49-82 ℃ by adjusting the molar ratios of PEGA to DEGA in the arm and the pH value of the solution. Furthermore, the prepared CCSP demonstrated a narrower temperature range of phase transition, thereby resulting in a faster phase separation process in comparison to the corresponding linear arm. [ABSTRACT FROM AUTHOR]

Traces of certain heavy metals are crucial for the metabolism of living beings, but poisoning occurs when their concentration increases. On the other hand, heavy metals such as lead, mercury, and cadmium lack functionality in higher organisms, resulting in considerable toxicity. Their long-term persistence is an environmental issue, being adsorption an alternative for the removal of metal pollutants, for example in wastewater. Adsorption has many advantages, such as high efficiency, simple design, low toxicity and reusable materials. Among the adsorbents, hydrogels feature improved resistance and high levels of swelling, comparable in costs to other common materials. In this work, we synthesized a copolymer of N,N -dimethylacrylamide (DMAa) and 2-hydroxyethyl methacrylate (HEMA) and evaluated its lead (II) adsorption capacity. The copolymer poly(HEMA-co-DMAa) was synthesized by a free-radical type bulk copolymerization of equal volumes of each monomer. The copolymer was characterized by 1 H and 13 C NMR, and Raman spectroscopies, and by the temperature and pH dependant-swelling effect of the hydrogel. Quantification of the removed Pb 2+ from probe solutions was performed by a UV spectrophotometric method as proposed by Krzek et al. Results suggest that at equilibrium, the amount of sorbed Pb(II) increased as the probe solution also increased (gradually from 10 to 200 ppm). Raman and 13 C spectroscopies confirmed effective copolymerization between HEMA and DMAa. The p(HEMA-co-DMAa) copolymer featured a swelling capacity up to 3.6 times their weight of water and exhibited a LCST in the range of 308–340 K with its geometric center around 313 K. In conclusion, a thermo-and-pH-responsive copolymer was obtained from the HEMA and DMAa monomers with LCST at 313 K and pH critical point at pH = 8, featuring efficient Pb(II) adsorption capabilities. The synthesized p(HEMA-co-DMAa) is promising for applications in heavy metals adsorption in aqueous systems with a broad range of pH and temperature, featuring resistance on adsorption and desorption cycles without mechanical degradation. [ABSTRACT FROM AUTHOR]

Transparent hydrogels have found increasing applications in wearable electronics, printable devices, and tissue engineering. Integrating desired properties, such as conductivity, mechanical strength, biocompatibility, and sensitivity, in one hydrogel remains challenging. To address these challenges, multifunctional hydrogels of methacrylate chitosan, spherical nanocellulose, and β-glucan with distinct physicochemical characteristics were combined to develop multifunctional composite hydrogels. The nanocellulose facilitated the self-assembly of the hydrogel. The hydrogels exhibited good printability and adhesiveness. Compared with the pure methacrylated chitosan hydrogel, the composite hydrogels exhibited improved viscoelasticity, shape memory, and conductivity. The biocompatibility of the composite hydrogels was monitored using human bone marrow-derived stem cells. Their motion-sensing potential was analyzed on different parts of the human body. The composite hydrogels also possessed temperature-responsiveness and moisture-sensing abilities. These results suggest that the developed composite hydrogels demonstrate excellent potential to fabricate 3D-printable devices for sensing and moist electric generator applications. [Display omitted] • 3D printable and transparent chitosan/nanocellulose hydrogels were synthesized. • Nanocellulose facilitated the self-assembly in the hydrogels. • The hydrogels showed enhanced viscoelasticity, shape memory, and adhesiveness. • Temperature-responsiveness and real-time motion sensing ability were demonstrated. • The hydrogels exhibited moist electric generation efficiency. [ABSTRACT FROM AUTHOR]

Phase-change materials (PCMs) are a type of special material which can store and release a large amount of thermal energy without any significant temperature change. They are emerging in recent years as a promising functional material in tumor therapy and theranostics due to their accurate responses to the temperature variations, biocompatibility and low toxicity. In this review, we will introduce the main types of PCMs and their desirable physiochemical properties for biomedical applications, and highlight the recent progress of PCM's applications in the modulated release of antitumor drugs, with special attentions paid to various ways to initiate temperature-dependent phase change, the concomitant thermal therapy and its combination with or activation of other therapies, particularly unconventional therapies. We will also summarize PCM's recent applications in tumor theranostics, where both drugs and imaging probes are delivered by PCMs for controlled drug release and imaging-guided therapy. Finally, the future perspectives and potential limitations of harnessing PCMs in tumor therapy will be discussed., Competing Interests: Declaration of competing interest The authors declare no conflict of interest., (Copyright © 2023. Published by Elsevier B.V.)

A polymer, poly(2-(2-methoxyethoxy)ethyl methacrylate) (PMDM), was accumulated on a silica microparticle by surface-initiated atom transfer radical polymerization (ATRP). The hydrodynamic diameter of the polymer-grafted silica particle (PMDM-SiP) dispersed in water was observed to decrease above 24 °C, which could be ascribed to a coil-globule transition of PMDM chains. This is in accordance with the increase in turbidity of an aqueous solution of free PMDM, which was produced parallel in liquid phase at the ATRP, above 23 °C. The lower critical solution temperature (LCST), defined as the temperature at which the absorbance reached the optical density of 0.30, was 27.6 °C for free PMDM. An introduction of zwitterionic vinyl monomer, carboxymethylbetaine (CMB), into both a polymer brush and a free polymer (P(MDM- r-CMB)) raised the LCST. In addition, the hydrodynamic diameter ( D) of the polymer-modified particles was not affected by the presence of NaBr nor lysozyme at 15 °C, whereas it was largely affected at 35 °C due to the decrease in hydrophilicity of the polymer graft chain above the LCST. In contrast, bovine serum albumin did not affect the D value of the polymer-modified particles both below and above the LCST. The usefulness of the PMDM brush having CMB as a comonomer in the biomedical field was suggested. [ABSTRACT FROM AUTHOR]

An inverse microemulsion polymerization was used to encapsulate lipase in polymer nanoparticles. The utilization of a non-ionic surfactant, polyoxyethylene-4-lauryl ether, in combination with sodium bis-2-ethylhexylsulfosuccinate reduced the charge density at the interfacial region of the microemulsion and thus favored the activity of lipase accommodated at the interfacial region of the microemulsion. At the optimized condition, 73.8 and 88.6 % of the original activity for lipase encapsulated in polyacrylamide and poly( N-isopropylacrylamide) (PNIPAM) nanoparticles were obtained. The lipase encapsulated in polyacrylamide nanoparticles exhibited a tenfold increase in the half-life time of enzyme activity at 50 °C. The temperature-responsive property of PNIPAM provided a temperature-controlled activity for the encapsulated lipase. Graphical Abstract: [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

We report on the effects of number and length of PEG chains in poly(depsipeptide-co-DL-lactide)-g-poly(ethylene glycol) (P(DG-DL-LA)-G-PEG) copolymers on their sol-to-gel transition behavior. The graft-type copolymer is suitable for the systematic study of the effects of molecular structure and hydrophilic/hydrophobic balance on its sol-to-gel transition. We prepared various P(DG-DI-LA)-G-PEG copolymers through coupling reactions between the pendant carboxylic acid groups of P(GD-DL-LA) and the end hydroxyl group of MeO-PEG having various molecular weights. Temperature-responsive sol-to-gel transition of the obtained copolymer solution in phosphate-buffered solution (pH 7.4, ionic strength = 0.14) was investigated by the test tube inverting method and rheological measurements. P(GD-NI.-LA)-G-PEG copolymer prepared from higher molecular weight PEG showed higher sol-to-gel transition temperatures compared with the copolymers prepared from lower molecu-lar weight PEG, although these copolymers have similar weight content of PEG (23-24 wt.%). Similar trends were observed for groups of copolymers whose PEG contents were 27 or 30 wt.%. These results are informative for providing strategies on rational design of thermo-gelling polymers. [ABSTRACT FROM AUTHOR]

In this work, micelles are formed by gradient copolymer of styrene and methyl methacrylate in acetone-water mixture and their temperature responsiveness is investigated in a narrow range near room temperature. Three different kinds of structural transitions could be induced by temperature: unimers to micelle transition, shrinkage/stretching of micelles, and morphological transition from spherical micelles to vesicles. In addition, a model analysis on the interface of gradient copolymer micelle is made to better understand these phenomena. It is found that both position and composition of the interface could alter in response to the change in temperature. According to the experiments and model analysis, it is proposed that temperature responsiveness might be an intrinsic and universal property of gradient copolymer micelles, which only originates from the gradient structure. [ABSTRACT FROM AUTHOR]

Objective(s)Physiological changes in the body may be utilized as potential triggers for controlled drug delivery. Based on these mechanisms, stimulus–responsive drug delivery has been developed.Materials and MethodsIn this study, a kind of poly (N-isopropylacrylamide-acrylamide) membrane was prepared by radical copolymerization. Changes in swelling ratios and diameters of the membrane were investigated in terms of temperature. On-off regulation of drug permeation through the membrane was then studied at temperatures below and above the phase transition temperature of the membrane. Two drugs, vitamin B12 and acetaminophen were chosen as models of high and low molecular weights here, respectively. ResultsIt was indicated that at temperatures below the phase transition temperature of the membrane, copolymer was in a swollen state. Above the phase transition temperature, water was partially expelled from the functional groups of the copolymer. Permeation of high molecular weight drug models such as vitamin B12 was shown to be much more distinct at temperatures below the phase transition temperature when the copolymer was in a swollen state. At higher temperatures when the copolymer was shrunken, drug permeation through the membrane was substantially decreased. However for acetaminophen, such a big change in drug permeation around the phase transition temperature of the membrane was not observed. ConclusionAccording to the pore mechanism of drug transport through hydrogels, permeability of solutes decreased with increasing molecular size. As a result, the relative permeability, around the phase transition temperature of the copolymer, was higher for solutes of high molecular weight.

Abstract: Silver (Ag) nanoparticles loading temperature responsive hybrid microgels were readily prepared by in situ reduction of Ag+ ions coordinated into poly(N-isopropylacrylamide) microgels. The weight percentage content of the entrapped Ag nanoparticles measured by thermogravity analysis tops 25%, and their average particle sizes determined by transmission electron microscopy are within the range from 8 to 11nm. The results obtained by X-ray diffraction exhibit that the Ag nanoparticles are of face-centered cubic single crystal structure. The particle sizes of the hybrid microgels decrease sharply with environmental temperature increasing from 30 to 35°C, and their surface plasmon resonance absorption wavelengths are pronouncedly red-shifted within the same temperature range. The catalytic reactivity of the Ag nanoparticles loading hybrid microgels can be tunable with four stages of change versus temperature from 20 to 45°C. [Copyright &y& Elsevier]

Abstract: Sex determination in Nile tilapia is very labile. It was shown that the sex ratio in temperature treated groups (36°C, 10days) of Oreochromis niloticus can be selected for as a quantitative trait. The standardized test procedure involved the artificial reproduction of breeders with nine days of egg incubation at 28°C and subsequent testing of fry at an elevated temperature of 36°C for 10days. Family selection was carried out upon the male percentages in treatment groups (high-line>80%, low-line<60%). Selected candidates were taken from corresponding full sib control groups, which were kept at 28°C. After two generations of divergent selection for the male proportion in temperature treated groups, male percentages of 90% and 54% were obtained in the high- and low-line, respectively. Herein, the data for a third generation of selection are presented. Twelve families in the high-line and 20 in the low-line were tested. Average male percentages in the treatment groups of 92.7% and 50.4% were obtained. After three generations of selection the cumulated realized heritabilities for the temperature dependent sex ratio were 0.63 in the high- and 0.84 in the low-line, still indicating good potential for selection. Two families in the high-line exhibited only males, whereas in the low-line two families showed a feminising effect in the treatment groups. Generally elevated temperatures (>34°C) are considered to be masculinising in Nile tilapia, feminising effects so far have only been reported in genetic all-male progenies (YY, XY). In the third generation of selection, it could be shown that elevated temperatures might take over a feminising role through selection in genetically mixed sex (XX/XY) progenies. Consequently both, temperature-masculinising and -feminising genes, exist in the same population and can be accumulated through selection. However, the load of temperature-masculinising genes of dams from the high- or low-line had no effect on mean sex ratios in temperature treated groups when a YY-male was used as a sire. From an evolutionary point of view, the prevalence of both temperature-masculinising and -feminising effects might allow the sex ratio to equilibrate at the population level if random mating occurs. This in turn might counteract the evolution of sex chromosomes. [Copyright &y& Elsevier]

The microcapsules with interpenetrating polymer network (IPN) structure based on crosslinked poly ( N-isopropylacrylamide) (PNIPAM) and crosslinked poly (acrylic acid) (PAA) were fabricated in a three-step process. Firstly, silica/PNIPAM core/shell composite particles were synthesized by thermo-initiated seed precipitation polymerization using 3-(trimethoxysilyl)propyl methacrylate modified silica colloidal particles as seeds and N-isopropylacrylamide and N, N′-methylenebisacrylamide (MBA) as monomer and crosslinker, respectively. Secondly, PAA network was incorporated into the shell of the composite particles by redox-initiated polymerization of acrylic acid and MBA entrapped in the PNIPAM network. Finally, the silica core of the composite particles was removed using hydrofluoric acid under certain condition to produce the microcapsules. The chemical compositions, their mass ratio, and particle sizes of the particles formed in each step were determined by Fourier transformation infrared spectroscopy, thermogravimetry, and dynamic laser light scattering (DLLS), respectively. The IPN structure of the microcapsules was identified by transmission electron microscopy (TEM) using uranyl acetate staining method, and their hollow structure was evidenced by TEM and scanning electron microscopy. Their temperature- or pH-dependent hydrodynamic diameters were measured by DLLS, and the results showed that the microcapules had both pH- and temperature-responsive properties, and the temperature-responsive component and the pH-responsive component inside the microcapsule shell had little interference with each other. [ABSTRACT FROM AUTHOR]

Objective(s) Physiological changes in the body may be utilized as potential triggers for controlled drug delivery. Based on these mechanisms, stimulus-responsive drug delivery has been developed. Materials and Methods In this study, a kind of poly (N-isopropylacrylamide-acrylamide) membrane was prepared by radical copolymerization. Changes in swelling ratios and diameters of the membrane were investigated in terms of temperature. On-off regulation of drug permeation through the membrane was then studied at temperatures below and above the phase transition temperature of the membrane. Two drugs, vitamin B12 and acetaminophen were chosen as models of high and low molecular weights here, respectively. Results It was indicated that at temperatures below the phase transition temperature of the membrane, copolymer was in a swollen state. Above the phase transition temperature, water was partially expelled from the functional groups of the copolymer. Permeation of high molecular weight drug models such as vitamin B12 was shown to be much more distinct at temperatures below the phase transition temperature when the copolymer was in a swollen state. At higher temperatures when the copolymer was shrunken, drug permeation through the membrane was substantially decreased. However for acetaminophen, such a big change in drug permeation around the phase transition temperature of the membrane was not observed. Conclusion According to the pore mechanism of drug transport through hydrogels, permeability of solutes decreased with increasing molecular size. As a result, the relative permeability, around the phase transition temperature of the copolymer, was higher for solutes of high molecular weight. [ABSTRACT FROM AUTHOR]

Abstract: Macroporous temperature-responsive poly(N-isopropylacrylamide) (PNIPAAm) hydrogels with high equilibrium swelling and fast response rates were obtained by a 60Co γ- and electron beam (EB) irradiation of aqueous N-isopropylacrylamide (NIPAAm) monomer solutions. The effect of irradiation temperatures, the dose, the addition of a pore-forming agent on the swelling ratio, and the kinetics of swelling and shrinking of the PNIPAAm gels was studied. The gels synthesized above the LCST exhibited the highest equilibrium swelling (300–400) and fastest response rate measured by minutes. Scanning electron microscope (SEM) pictures revealed that the gels synthesized above the LCST have larger pores than those prepared at temperatures below the LCST. The gels showed a reversible response to cyclical changes in temperature and might be used in a pulsed drug delivery device. The gels synthesized above the LCST exhibited the highest testosterone propionate release. [Copyright &y& Elsevier]

By coupling two equivalents of N,N-diethyldithiocarbamoylmethylbenzoic acid succinimidyl ester with cystamine dihydrochloride, a disulfide-carrying compound (Cys-BDC) was prepared and used as iniferter (a compound which pursues initiation, chain transfer, and termination) in the telomerization of N,N-dimethylacrylamide and 3-acrylamidophenylboronic acid. The telomerization was carried out in the presence of N,N,N′,N′-tetraethylthiuram disulfide under photoirradiation at 365 nm. An aqueous solution of the telomer obtained showed responsiveness to both temperature and sugars as confirmed by the turbidity measurements. The telomer formed a self-assembled monolayer (SAM) on a gold surface as confirmed by both cyclic voltammetry (CV) and ellipsometry. The recognition of sugar residues by the telomer SAM constructed on the gold electrode was detected by the CV measurements. The usefulness of the iniferter to prepare various telomer-carrying SAMs with bio-related functions was strongly suggested. [Copyright &y& Elsevier]

Stimuli-responsive polyampholyte hydrogels were synthesized by the copolymerization of dimethylaminoethyl methacrylate (DMAA) and acrylic acid (AAc) or itaconic acid (IAc) by UV-irradiation. Temperature and pH responsiveness of these hydrogels were studied. The temperature responsiveness of poly-(DMAA-co-AAc, IAc) hydrogels shown in change of water content became dull compared to that of DMAA homo-polymer hydrogel. The water content of the poly-(DMAA-co-AAc, IAc) hydrogels showed a minimum at pH 8, and increased in more acidic and alkaline regions. This fact can be attributed to the coexistence of anions and cations in the poly-(DMAA-co-AAc, IAc) hydrogels. The poly-(DMAA-co-AAc, IAc) hydrogels were polyampholyte having both temperature responsiveness and pH responsiveness. [Copyright &y& Elsevier]

A series of multi-stimuli responsive water-soluble copolymers with higher porphyrin content were synthesized. [Display omitted] • A series of water-soluble copolymers with higher porphyrin content were synthesized. • The obtained porphyrin copolymers aqueous solution showed responsive behavior to temperature, ionic strength and pH. • The photo-thermal conversion efficiency of porphyrin copolymer aqueous solutionat can achieve 25.34%. Water-soluble porphyrins have played an important role and showed potential application value in photodynamic therapy, sensor and aqueous photocatalysis. Most of the reported water-soluble porphyrin polymers have low porphyrin content, which is difficult to give full play to the role of porphyrin. To improve the content of porphyrin in polymers, we introduced the hydrophilic chain into the porphyrin molecule to obtain the hydrophilic porphyrin monomer, and then copolymerized with the hydrophilic monomer N-isopropylacrylamide to obtain the water-soluble copolymers with higher porphyrin content. The prepared porphyrin copolymers aqueous solution also showed responsive behavior to temperature, ionic strength and pH. Firstly, temperature affects the solvability and photophysical properties of copolymers. When heating the temperature above their cloud point, the copolymers chain aggregated, leading to the decreased light transmittance and enhanced emission intensity. Secondly, the copolymer aqueous solution showed responsive behavior to ionic strength. After adding different sodium salts into the copolymer aqueous solution, the changes order of cloud point was completely consistent with the Hofmeister series, and their emission intensity also varied. Finally, the copolymer aqueous solution showed responsive behavior to pH. When the pH of copolymer aqueous solution decreased, the inner nitrogen atoms in porphyrin ring were protonated, resulting in an increase in the cloud point of their aqueous solution. At the same time, the maximum absorption peak gradually red-shifted, and the emission intensity also decreased. Therefore, based on the decrease in fluorescence, the protonated copolymer could be used as photo-thermal conversion materials. The measured photo-thermal conversion efficiency (PCE) of the copolymer in the pH = 1.0 aqueous solution was 25.34%. [ABSTRACT FROM AUTHOR]

• GA-based composite with temperature responsiveness were synthesized. • The composite can adaptively switch absorbing frequency band as temperature change. • The composite exhibits recyclable thermal and electric properties. Smart microwave absorption (MA) materials with responsiveness to environment are highly desired in modern communication systems, while designing and fabricating high-performance microwave absorbers with adaptivity to working in dynamic service environment is still a challenge. Here we report a temperature-responsive composite composing covalently bonded poly(N-isopropylacrylamide) (PNIPAAm) and graphene aerogel (GA)for adaptive MA. The dynamic change of hydrogen bonds actuate the conformation change of PNIPAAm chains when the temperature varies below and above the critical transition temperature of 34.8℃, which drives the reduced graphene oxide sheets in GA to delaminate and restacking simultaneously. As a result, the electrical, dielectric and thermal properties of the composite become adaptively switchable. More important, the composite is capable of achieving an effective MA within quite different frequency bands under stimuli of temperature changes. Typically, at 20℃, the effective absorbing band (below −10 dB) ranges from 8.5 to 17.5 GHz, and the minimum reflection loss (RL min) reaches −32 dB, while when the temperature increases to 50℃, the effective absorbing band shifts to 4.5 ~ 14.0 GHz with the same RL min. This temperature-responsive composite has great potential of being used as smart devices, especially the advanced electromagnetic protection equipment in the modern communication systems. [ABSTRACT FROM AUTHOR]

A highly water-soluble rosin-based surfactant (C 14 -MPA-Na) was synthesized. Novel temperature-responsive supramolecular hydrogels were further prepared using C 14 -MPA-Na. The microstructure and the mechanical properties of the hydrogels were investigated. Unexpectedly, instead of the long one-dimensional structure, a new kind of twisted semicircular aggregate was formed in the hydrogels, which was rarely reported. Besides, the hydrogels possessed excellent shear-recovery properties. Upon heating to 40 °C, the hydrogels transformed into viscoelastic solutions, which were constructed by worm-like micelles. By adjusting the temperature, the hydrogels and the viscoelastic solutions could be freely transformed. Nuclear magnetic resonance spectroscopy and Fourier transform infrared spectroscopy were used to further explore the possible self-assembly mechanism of C 14 -MPA-Na. The curved alkane chain which partially overlapped with rosin's rigid skeleton became stretched when heated to 40 °C. The introduction of the rosin rigid skeleton endowed the supramolecular hydrogels with a novel microstructure and contributed to the development of strategies for the utilization of forest resources.

• Chitosan derivatives were prepared based on homogeneous reaction system. • Temperature-driven phase transition between dissolution and nanohydrogel states. • Phase change process could be repeated more than 50 cycles (one cycle/day). • The nanohydrogels solution exhibited superior UV blocking. • Intelligent optical regulation of HBC could be applied in smart window. Chitosan (CS) based self-assembled nanohydrogels are considered as promising platform for biomedicine, petrochemical, agricultural and food applications due to their unique biodegradability, nano-interface effect, and intelligent responsiveness. However, the most CS derivatives are prepared in heterogeneous system, which is unstable and environmentally unfriendly. In this work, a series of hydroxybutyl chitosan (HBC) was synthesized based on a green and homogeneous system (potassium hydroxide (KOH)/urea), which given this derivative interesting temperature responsive phase transformation behavior. HBC could change from dissolved state into nanohydrogel state in deionized water, when the temperature exceed its critical phase change temperature, and this process could be repeated more than 50 cycles (one cycle/day) without coagulation. The nanohydrogels solution exhibited concentration and temperature-dependent ultraviolet absorption and visible light regulation, which had great application potential in smart windows. This study provided a novel preparation method and extended the application of chitosan-based temperature responsive self-assembled nanohydrogels. [ABSTRACT FROM AUTHOR]