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Poly (N-vinylcaprolactam) (PNVCL) and poly (N-isopropylacrylamide) (PNIPAm) are two popular negatively temperature-responsive hydrogels, due to their biocompatibility, softness, hydrophilicity, superabsorbency, viscoelasticity, and near-physiological lower critical solution temperature (LCST). These characteristics make them ideal for biomedical applications. When combined with other materials, hydrogel expansion induces the morphing of the assembly due to internal stress differences. Our recent developments in NVCL hydrogel, enhanced by nanoclay incorporation, have driven us to the creation of a bilayer structure to study its shapeshifting response across various temperatures. This study focused on the bending behaviour of bilayer samples composed of an active hydrogel layer and a passive non-swellable layer. Using photopolymerisation, circular discs and rectangular bilayer samples of varying sizes were fabricated. Homogeneous circular samples demonstrated that hydrogel density increased proportionally with temperature, with the swelling ratio exhibiting two distinct rates of change below and above its LCST. In bilayer samples, the volume of the passive layer influenced bending, and its optimal volume was identified. The investigation revealed that geometry affected the overall bending effect due to changes in the passive layer stiffness. Lastly, a temperature-responsive gripper capable of picking up objects several times its own weight was demonstrated, highlighting the potential of NVCL hydrogels as bioactuators for minimally invasive surgery. [ABSTRACT FROM AUTHOR]

Structurally well‐defined small molecules with lower critical solution temperature (LCST) behavior offer enormous prospects for fine‐tuning their phase transition properties to be "on‐demand" applied in the specific scene but are still underexplored. Herein, a novel amphiphilic small LCST molecule is rationally designed and synthesized. The molecule, namely TG, features a conjugation of multiple short ethylene glycol (EG) chains with the functional coordinating terpyridine (Tpy) moiety. The molecule TG demonstrates excellent LCST behavior down to 0.05 × 10−3m in a water solution. And a cloud point Tcp = 30.9 °C with a very short thermal hysteresis ΔT = 0.2 °C and good reversibility can be achieved when c = 0.1 × 10−3m. The excellent LCST properties of TG have enabled its successful performance as the smart window for solar radiation management with the ∆Tlum, ∆TIR, and ∆Tsol being 83.6%, 49.1%, and 67.2%, respectively. Moreover, the presence of Tpy moiety in TG enables its coordination with Ru3+ and the resulting complex also exhibits modulated LCST behavior with different concentration‐dependent Tcp. These studies would provide novel small‐molecule‐based scaffolds for constructing better solar radiation management systems as well as other thermal‐responsive smart materials. [ABSTRACT FROM AUTHOR]

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]

Gold nanoparticles (AuNPs) possess attractive electronic, optical, and catalytic properties, enabling many potential applications. Poly(N-isopropyl acrylamide) (PNIPAAm) is a temperature-responsive polymer that changes its hydrophilicity upon a slight temperature change, and combining PNIPAAm with AuNPs allows us to modulate the properties of AuNPs by temperature. In a previous study, we proposed a simpler method for designing PNIPAAm–AuNP hybrid microgels, which used an AuNP monomer with polymerizable groups. The size of AuNPs is the most important factor influencing their catalytic performance, and numerous studies have emphasized the importance of controlling the size of AuNPs by adjusting their stabilizer concentration. This paper focuses on the effect of AuNP size on the catalytic activity of PNIPAAm–AuNP hybrid microgels prepared via the copolymerization of N-isopropyl acrylamide and AuNP monomers with different AuNP sizes. To quantitatively evaluate the catalytic activity of the hybrid microgels, we monitored the reduction of 4-nitrophenol to 4-aminophenol using the hybrid microgels with various AuNP sizes. While the hybrid microgels with an AuNP size of 13.0 nm exhibited the highest reaction rate and the apparent reaction rate constant (kapp) of 24.2 × 10−3 s−1, those of 35.9 nm exhibited a small kapp of 1.3 × 10−3 s−1. Thus, the catalytic activity of the PNIPAAm–AuNP hybrid microgel was strongly influenced by the AuNP size. The hybrid microgels with various AuNP sizes enabled the reversibly temperature-responsive on–off regulation of the reduction reaction. [ABSTRACT FROM AUTHOR]

The effect of amphiphilic block copolymer polyethylene glycol (PEG)-polypropylene glycol (PPG)-PEG concentration in the polyphenylsulfone (PPSU) casting solution and coagulation bath temperature (CBT) on the structure, separation, and antifouling performance of PPSU ultrafiltration membranes was studied for the first time. According to the phase diagram obtained, PPSU/PEG-PPG-PEG/N-methyl-2-pyrrolidone (NMP) systems are characterized by a narrow miscibility gap. It was found that 20 wt.% PPSU solutions in NMP with the addition of 5–15 wt.% of PEG-PPG-PEG block copolymer feature upper critical solution temperature, gel point, and lower critical solution temperature. Membrane composition and structure were studied by Fourier-transform infrared spectroscopy, scanning electron and atomic force microscopies, and water contact angle measurements. The addition of PEG-PPG-PPG to the PPSU casting solution was found to increase the hydrophilicity of the membrane surface (water contact angle decreased from 78° for the reference PPSU membrane down to 50° for 20 wt.%PPSU/15 wt.% PEG-PPG-PEG membrane). It was revealed that the pure water flux increased with the rise of CBT from 18–20 L·m−2·h−1 for the reference PPSU membrane up to 38–140 L·m−2·h−1 for 20 wt.% PPSU/10–15 wt.% PEG-PPG-PEG membranes. However, the opposite trend was observed for 20 wt.% PPSU/5–7 wt.% PEG-PPG-PEG membranes: pure water flux decreased with an increase in CBT. This is due to the differences in the mechanism of phase separation (non-solvent-induced phase separation (NIPS) or a combination of NIPS and temperature-induced phase separation (TIPS)). It was shown that 20 wt.% PPSU/10 wt.% PEG-PPG-PEG membranes were characterized by significantly higher antifouling performance (FRR—81–89%, DRr—26–32%, DRir—10–20%, DT—33–45%) during the ultrafiltration of bovine serum albumin solutions compared to the reference PPSU membrane prepared at different CBTs (FRR—29–38%, DRr—6–14%, DRir—74–89%, DT—88–94%). [ABSTRACT FROM AUTHOR]

Poly(2-cyano-p-phenylene terephthalamide) (CY-PPTA) has garnered significant interest as a promising precursor for super p-aramid fibers because of its organosolubility in N,N-dimethyl acetamide/lithium chloride (DMAc/LiCl) while conserving the superior properties of the resultant fibers. However, CY-PPTA has been reported to exhibit abnormal phase behavior owing to the strong dipole–dipole interactions induced by the cyano groups. Herein, we rheologically study the isotropic phases of CY-PPTA/DMAc solutions with respect to the concentration and temperature and compare them with those of CY-PPTA/sulfuric acid (H2SO4) solutions. In the isotropic region, the CY-PPTA solutions yield a higher power-law exponent of the dynamic viscosity (η') versus concentration of 6.0 (ηʹ ~ c6.0) in the DMAc system than that in H2SO4 (ηʹ ~ c3.2). Moreover, the CY-PPTA/DMAc solutions exhibit a lower critical solution temperature (LCST) behavior with increasing temperature, in contrast with the upper critical solution temperature in H2SO4. Consequently, the viscosity and exponent of the CY-PPTA/DMAc solutions increase at elevated temperatures. As shown by the Cole–Cole plot, the heterogeneity in the DMAc system becomes worse. The LCST of the CY-PPTA solution is ascribed to the intermolecular interactions between the highly polar cyano groups, which are negligible in H2SO4. [ABSTRACT FROM AUTHOR]

Personal thermal management (PTM) textiles with heating or cooling capabilities are highly attractive because they offer individual comfort and contribute to lower energy consumption. However, due to the subjectivity of thermal comfort, developing adaptive and personalized PTM textiles remains a challenge. Here, we report a thermoresponsive cotton fabric (PMOG-cotton), which is prepared by a combination of ultraviolet-induced free radical polymerization and pad-dry-cure process. 2-(2-methoxyethoxy)ethyl methacrylate (MEO2MA) and oligo(ethylene glycol) methacrylate (OEGMA475) are selected as thermoresponsive monomers, while glycidyl methacrylate (GMA) is chosen as the linking monomer for copolymerization. The lower critical solution temperature (LCST) of P(MEO2MA-co-OEGMA475-co-GMA) can be precisely regulated by adjusting the dosage of OEGMA475. Furthermore, PMOG-cotton demonstrates a reversible transition between hydrophobic and hydrophilic states in response to variations in external temperature (T > LCST, hydrophobic; T < LCST, hydrophilic). This transition can be sustained for a minimum of 5 cycles and 50 rubbing cycles. PMOG-cotton exhibits superior control over breathability and moisture permeability compared to raw cotton in response to temperature fluctuations. Compared to raw cotton, PMOG-cotton offers a 2.4 °C heating effect in cold environments and a 1.3 °C cooling effect in hot environments. This adaptive thermal management textile shows promise for delivering human thermal comfort in complex and dynamic environments. [ABSTRACT FROM AUTHOR]

Poly(N-vinylcaprolactam-co-hydroxyethyl acrylate-co-phenyl vinyl sulfide) (poly(VC-co-HEA-co-PVS)) and poly(N-vinylcaprolactam-co-N-vinylpyrrolidone-co-phenyl vinyl sulfide) (poly(VC-co-VP-co-PVS)) were synthesized as thermos-sensitive oxidizable terpolymers. The copolymerization was confirmed by the 1H-NMR and FT-IR spectroscopy. VC homopolymer exhibited its lower critical solution temperature (LCST) around 32 ℃. The copolymerization of HEA with VC and of VP with VC decreased and increased the LCST of VC homopolymer, respectively. The inclusion of PVS (an oxidizable monomer) in the copolymers decreased the LCST. The PVS of the copolymers could be oxidized by H2O2, solution (0.1%), evidenced by 1H-NMR spectroscopy. Upon the oxidation, the LCST of poly(VC-co-PVS) and poly(VC-co-HEA-co-PVS) increased markedly possibly due to an increase in the hydrophilicity of PVS. However, the LCST of poly(VC-co-VP-co-PVS) was not markedly affected by the oxidation. The interface activity of poly(VC-co-PVS) and poly(VC-co-HEA-co-PVS) slightly decreased but that of poly(VC-co-VP-co-PVS) markedly increased by the oxidation. The critical micelle concentration of the copolymers was determined by a fluorescence method, and it was 0.087 to 0.105 mg/mL. The micelles of the copolymers were found as circular objects on a transmission electron microscope. The mean hydrodynamic diameters of micelles were 107.4 to 471.6 nm, depending on the polymer composition. The PVS-containing copolymers formed larger micelles than VC homopolymer, possibly because the monomer could enhance an intermolecular hydrophobic interaction due to its phenyl group. [ABSTRACT FROM AUTHOR]

It has been found that the thermoresponsive behavior of emulsions stabilized by block copolymer surfactants (BCSs) can induce either gelation or emulsion break‐up with mild temperature changes. A hydrophilic, steric‐stabilizing component of the BCS, polyethylene glycol methacrylate (PEGMA), is crucial to control the thermoresponsive behavior of the emulsions: longer PEG chains (950 g mol−1) lead to thermoregulation, whereas shorter PEGM chains (500 or 300 g mol−1) lead to emulsion break‐up upon mild heating. Additionally, the relative abundance of PEGMA to the thermoresponsive component in the BCS controls the gelation temperature of BCS‐stabilized emulsions. Small‐angle neutron scattering and transmission electron microscopy reveal that the BCS forms oblate ellipsoids which grow anisotropically with temperature. In samples that form a gel, there is evidence that these nano‐objects form supra‐colloidal structures, which are responsible for the gel mesophase formation. An optimal BCS can form emulsions that transition from a liquid to gel state when warmed above 32 °C. This makes the system ideal for in situ gelation upon contact with the body. Overall, this study highlights the great potential of BCSs in generating thermoresponsive emulsions for drug delivery and other healthcare applications. [ABSTRACT FROM AUTHOR]

Artificial Intelligence (AI) technology has been increasingly applied in the field of chemistry in recent years. For proof of concept for the application of AI technology to polymer research, a state‐of‐the‐art machine learning (ML) technique is employed to systematically elucidate the lower critical solution temperature (LCST) of N‐isopropylacrylamide (NIPAAm) copolymers using data collected from the literature. The information on 110 NIPAAm random copolymers is collected to extract their LCSTs and the chemical and physical parameters of the copolymers and comonomers. The ML analysis reveals that the copolymerized ratio, the elemental composition of carbon and oxygen in the comonomers, and the water solubility of the comonomers are crucial parameters affecting the LCST, and the constructed ML model successfully predicts the LCSTs of various NIPAAm copolymers. Furthermore, the genetic algorithm using symbolic regression identifies a simple and comprehensive descriptor for the LCST. This study demonstrates the usefulness of data‐driven ML techniques for polymer research with the rapid and accurate prediction of polymer properties. [ABSTRACT FROM AUTHOR]

In this paper, the kinetic stability of Pickering emulsions stabilized by spherical silica particles (100 nm in diameter) was examined in the water – 2,6-lutidine mixture. In the close vicinity of the lower critical solution temperature, Pickering emulsions were unstable due to the ultra-low liquid-liquid interfacial tension but increased their stability with increasing the temperature. In this system, the interfacial tension obeys universal scale law and can be tuned by temperature without adding any surfaceactive agents. Owing to this unique feature, we elucidated the relation between the interfacial tension and the stability of Pickering emulsions. [ABSTRACT FROM AUTHOR]

Development of block copolymer (BCP) microparticles with switchable morphology in response to external stimuli is important for exploiting new intelligent materials. In this work, thermo/pH dual-responsive nanoparticles (NPs) were employed as a co-surfactant to modulate the self-assembly morphology of polystyrene-b-poly(2-vinylpyridine) (PS-b-P2VP) microparticles within confined emulsion droplets. The co-surfactant was synthesized by grafting poly(acrylic acid)-b-poly(N-isopropylacrylamide) onto the surface of Fe3O4 NP. The introduction of the dual-responsive co-surfactant enabled thermo/pH dual-responsive reversible morphology transition of the PS-b-P2VP microparticles by tailoring the hydrophobicity and interfacial affinity of the co-surfactant. By using this strategy, the thermo-inert PS-b-P2VP self-assembled into pupa-like microparticles at T = 10 °C and pH 7.5, which could transform into tulip-like microparticles when T was increased to 50 °C. When the pH value was increased to 11, the pupa-like particles turned into onion-like microparticles although the PS-b-P2VP was inert to alkali. However, the pupa-like microparticles remained unchanged when both T and pH were simultaneously increased. The PAA-b-PNIPAM-grafted Fe3O4 NP surfactants showed obvious advantages over the linear PAA-b-PNIPAM surfactants in modulating the morphology transition, since the linear PAA-b-PNIPAM could not induce the reversible shape transition of microparticles. Our work provides an efficient strategy to achieve reversible shape transformation of BCP microparticles while the internal phase structure is preserved, which may be utilized to switch the structural color properties of BCP microparticles. [ABSTRACT FROM AUTHOR]

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 It has been found that the thermoresponsive behavior of emulsions stabilized by block copolymer surfactants (BCSs) can induce either gelation or emulsion break‐up with mild temperature changes. A hydrophilic, steric‐stabilizing component of the BCS, polyethylene glycol methacrylate (PEGMA), is crucial to control the thermoresponsive behavior of the emulsions: longer PEG chains (950 g mol−1) lead to thermoregulation, whereas shorter PEGM chains (500 or 300 g mol−1) lead to emulsion break‐up upon mild heating. Additionally, the relative abundance of PEGMA to the thermoresponsive component in the BCS controls the gelation temperature of BCS‐stabilized emulsions. Small‐angle neutron scattering and transmission electron microscopy reveal that the BCS forms oblate ellipsoids which grow anisotropically with temperature. In samples that form a gel, there is evidence that these nano‐objects form supra‐colloidal structures, which are responsible for the gel mesophase formation. An optimal BCS can form emulsions that transition from a liquid to gel state when warmed above 32 °C. This makes the system ideal for in situ gelation upon contact with the body. Overall, this study highlights the great potential of BCSs in generating thermoresponsive emulsions for drug delivery and other healthcare applications.

[Display omitted] Schizophrenic copolymers are one type of the popular smart polymers that show invertible colloidal structures in response to temperature stimulus. However, the lack of principles to predict the phase transition temperature of a schizophrenic copolymer from its corresponding parent thermo-responsive polymers limits their development. Additionally, studies on their applications remain scarce. Herein, a series of schizophrenic copolymers were synthesized by polymerization of a RAFT-made polymer precursor poly(acrylamide- co - N -acryloxysuccinimide- co -acrylic acid) (P(AAm- co -NAS- co -AAc)) with the mixture of N -isopropylmethacrylamide (NIPAm) and acrylamide (AAm) in varying molar ratios. In aqueous solution, the block P(AAm- co -NAS- co -AAc) and the block poly(NIPAm- co -AAm) exhibited upper and lower critical solution temperature (UCST and LCST) behavior, respectively. The schizophrenic copolymers featured either UCST-LCST, LCST-UCST, or only LCST thermo-responsive transition. A preliminary correlation of phase transition between the schizophrenic copolymers and their parent polymers was summarized. Furthermore, the co-assembly of the schizophrenic copolymers and proteins were conducted and the kinetics of protein loading and protein activity were investigated, which showed that the schizophrenic copolymers were efficient platforms for protein co-assembly with ultra-high protein loading while preserving the protein bioactivities. Additionally, all the materials were non-toxic towards NIH 3T3 and MCF-7 cells. This work offers the prospects of the schizophrenic polymers in soft colloidal and assembly systems, particularly in guiding the design of new materials and their use in biomedical applications. [ABSTRACT FROM AUTHOR]

Degenerative intervertebral disc disease is a common source of chronic pain and reduced quality of life in people over the age of 40. While degeneration occurs throughout the disc, it most often initiates in the nucleus pulposus (NP). Minimally invasive delivery of NP cells within hydrogels that can restore and maintain the disc height while regenerating the damaged NP tissue is a promising treatment strategy for this condition. Towards this goal, a biohybrid ABA dimethacrylate triblock copolymer was synthesized, possessing a lower critical solution temperature below 37 °C and which contained as its central block an MMP-degradable peptide flanked by poly(trimethylene carbonate) blocks bearing pendant oligoethylene glycol groups. This triblock prepolymer was used to form macroporous NP cell-laden hydrogels via redox initiated (ammonium persulfate/sodium bisulfite) crosslinking, with or without the inclusion of thiolated chondroitin sulfate. The resulting macroporous hydrogels had water and mechanical properties similar to those of human NP tissue and were mechanically resilient. The hydrogels supported NP cell attachment and growth over 28 days in hypoxic culture. In hydrogels prepared with the triblock copolymer but without the chondroitin sulfate the NP cells were distributed homogeneously throughout in clusters and deposited collagen type II and sulfated glycosaminoglycans but not collagen type I. This hydrogel formulation warrants further investigation as a cell delivery vehicle to regenerate degenerated NP tissue. The intervertebral disc between the vertebral bones of the spine consists of three regions: a gel-like central nucleus pulposus (NP) within the annulus fibrosis, and bony endplates. Degeneration of the intervertebral disc is a source of chronic pain in the elderly and most commonly initiates in the NP. Replacement of degenerated NP tissue with a NP cell-laden hydrogel is a promising treatment strategy. Herein we demonstrate that a crosslinkable polymer with a lower critical solution temperature below 37 °C can be used to form macroporous hydrogels for this purpose. The hydrogels are capable of supporting NP cells, which deposit collagen II and sulfated glycosaminoglycans, while also possessing mechanical properties matching those of human NP tissue. [Display omitted] [ABSTRACT FROM AUTHOR]

This article reports the synthesis of poly(N-vinylcaprolactam-co-N-methylolacrylamide) (P(NVCL-co-NMA)) nanogels and investigates their thermo-/pH-responsive behavior. The formation of nanogels was synthesized using free radical emulsion polymerization by varying the monomer composition of NVCL:NMA, and their molecular structure was characterized by 1H-NMR and FTIR. It was found that the nanogels were successfully prepared, and the nanogels exhibited LCST-type phase transition behavior. Cloud point transition temperature (Tc) was studied as a function of copolymer composition, MBA concentration, and pH of the solution by exploring their changes in turbidity using UV–vis spectrophotometer. Our studies reveal that Tc nanogels increased with increasing concentration of NMA, which is due to the hydrophilicity of NMA. Our research also demonstrated that the increase in MBA percentage could decrease the Tc of the synthesized nanogels. Interestingly, P(NVCL-co-NMA) nanogels showed not only a thermoresponsive behavior but also a pH response with increasing Tc in a strong acidic environment owing to the H-bonds within the polymer chains. The results show that nanogels with initial monomer composition of NVCL and NMA of 75% and 25%, respectively, and using 4% of MBA showed Tc around 35°C at pH 7.4. In addition, DLS studies also confirmed this result since the particle sizes became much larger after surpassing the temperature of 35°C. Due to this founding, such nanogels might have potential application in controlled release. Nevertheless, further studies regarding the adjustment of Tc are still needed.

We theoretically study nematic-isotropic phase transitions and phase separations in aqueous rodlike polymer solutions, such as rigid DNA (or rodlike polymer) in water. By taking into the hydrogen bonding between a rodlike polymer and solvent molecules, we predict novel phase diagrams, such as overhang-type coexistence curves with isotropic-nematic ($$I + N$$ I + N) phase separations and re-entrant $$I + N$$ I + N separations. We demonstrate that the hydrogen bonding between molecules of different components stabilises the nematic phase at lower polymer concentrations and temperatures. [ABSTRACT FROM AUTHOR]

Sets of the nonionic polymers poly(N-vinyl isobutyramide) (pNVIBAm) and poly(N-isopropyl methacrylamide) (pNIPMAm) are synthesized by radical polymerization covering the molar mass range from about 20,000 to 150,000 kg mol−1, and their thermoresponsive and solvent-responsive behaviors in aqueous solution are studied. Both polymers feature a lower critical solution temperature (LCST) apparently of the rare so-called type II, as characteristic for their well-studied analogue poly(N-isopropyl acrylamide) (pNIPAm). Moreover, in analogy to pNIPAm, both polymers exhibit co-nonsolvency behavior in mixtures of water with several co-solvents, including short-chain alcohols as well as a range of polar aprotic solvents. While the cloud points of the aqueous solutions are a few degrees higher than those for pNIPAm and increase in the order pNIPAm < pNVIBAm < pNIPMAm, the co-nonsolvency behavior becomes less pronounced in the order pNIPAm > pNVIBAm > pNIPMAm. Exceptionally, pNIPMAm does not show co-nonsolvency in mixtures of water and N,N-dimethylformamide. [ABSTRACT FROM AUTHOR]

Gold nanoparticles (AuNPs) possess attractive electronic, optical, and catalytic properties, enabling many potential applications. Poly(N-isopropyl acrylamide) (PNIPAAm) is a temperature-responsive polymer that changes its hydrophilicity upon a slight temperature change, and combining PNIPAAm with AuNPs allows us to modulate the properties of AuNPs by temperature. In a previous study, we proposed a simpler method for designing PNIPAAm–AuNP hybrid microgels, which used an AuNP monomer with polymerizable groups. The size of AuNPs is the most important factor influencing their catalytic performance, and numerous studies have emphasized the importance of controlling the size of AuNPs by adjusting their stabilizer concentration. This paper focuses on the effect of AuNP size on the catalytic activity of PNIPAAm–AuNP hybrid microgels prepared via the copolymerization of N-isopropyl acrylamide and AuNP monomers with different AuNP sizes. To quantitatively evaluate the catalytic activity of the hybrid microgels, we monitored the reduction of 4-nitrophenol to 4-aminophenol using the hybrid microgels with various AuNP sizes. While the hybrid microgels with an AuNP size of 13.0 nm exhibited the highest reaction rate and the apparent reaction rate constant (kapp) of 24.2 × 10−3 s−1, those of 35.9 nm exhibited a small kapp of 1.3 × 10−3 s−1. Thus, the catalytic activity of the PNIPAAm–AuNP hybrid microgel was strongly influenced by the AuNP size. The hybrid microgels with various AuNP sizes enabled the reversibly temperature-responsive on–off regulation of the reduction reaction.

In this study, pH and thermally responsive P(PFPHM9‐b‐DMAEMA‐b‐PEGMEA480) was prepared by atom transfer radical polymerization (ATRP) using perfluoropolyether hydroxyethyl methacrylate (PFPHM) as hydrophobic core, 2‐(Dimethylamino) ethyl methacrylate as pH and thermal response function segment, and poly (ethylene glycol) methyl ether acrylate480 as hydrophilic shell, respectively. The chemical structure, critical micelle concentration (CMC), lower critical solution temperature (LCST), biological toxicity, stability of micelles, drug‐loading performance and cumulative drug release rate of prepared P(PFPHM9‐b‐DMAEMA‐b‐PEGMEA480) were analyzed by 19F NMR, 1H NMR, FTIR, DLS, UV–Vis, laser confocal microscopy and fluorescence spectrophotometer. The results show that P(PFPHM9‐b‐DMAEMA‐b‐PEGMEA480) exhibites a CMC of 7.5 g/L, LCST of 37.6°C and excellent micelle stability. Moreover, the analysis of drug‐loading indicates that the polymer displayed drug loading efficiency (DL) is 21.3% and the encapsulation efficiency (EE) is 90.0%. Its cumulative drug release rates at pH = 6.5 (42°C) is almost double of those at pH = 7.4 (42°C), pH = 6.5 (37°C) and pH = 7.4 (37°C). These results suggeste that the P(PFPHM9‐b‐DMAEMA‐b‐PEGMEA480) at pH ranging from 6.5 to 7.4 and temperature ranging from 37 to 42°C are pH and temperature sensitive. It has great potential application as a drug loading for DOX. [ABSTRACT FROM AUTHOR]

Four-dimensional printing is primarily based on the concept of 3D printing technology. However, it requires additional stimulus and stimulus-responsive materials. Poly-N-vinylcaprolactam is a temperature-sensitive polymer. Unique characteristics of poly-N-vinylcaprolactam -based hydrogels offer the possibility of employing them in 4D printing. The main aim of this study is to alter the phase transition temperature of poly-N-vinylcaprolactam hydrogels. This research focuses primarily on incorporating two additional monomers with poly-N-vinylcaprolactam: Vinylacetate and N-vinylpyrrolidone. This work contributes to this growing area of research by altering (increasing and decreasing) the lower critical solution temperature of N-vinylcaprolactam through photopolymerisation. Poly-N-vinylcaprolactam exhibits a lower critical solution temperature close to the physiological temperature range of 34–37 °C. The copolymers were analysed using various characterisation techniques, such as FTIR, DSC, and UV-spectrometry. The main findings show that the inclusion of N-vinylpyrrolidone into poly-N-vinylcaprolactam increased the lower critical solution temperature above the physiological temperature. By incorporating vinylacetate, the lower critical solution temperature dropped to 21 °C, allowing for potential self-assembly of 4D-printed objects at room temperature. In this case, altering the lower critical solution temperature of the material can potentially permit the transformation of the 4D-printed object at a particular temperature. [ABSTRACT FROM AUTHOR]

[Display omitted] PNIPAM as a stimuli-responsive polymer has generated extreme interests due to its versatile applications. However, there is no research report on whether PNIPAM micro/nano-particles can be extracted from its suspension after phase separation. In the present work, LCST-type phase separation in self-synthesized PNIPAM/water system was investigated in depth by dividing the DLS testing process into four stages. In addition to quenching duration, temperature rise process, quenching temperature and PNIPAM concentration all have a great influence on particle size of the suspension. Meanwhile, the steady-state rheology and dynamic viscoelasticity results show that PNIPAM micro/nano-particles in the suspension are "soft" that can deform. Finally, FE-SEM was used to observe the morphology of dehydrated PNIPAM extracted by sessile droplet evaporation under different conditions. The results indicate that these "soft" particles are easier to fuse together, do not have sufficient mechanical strength to maintain their spherical morphology after dehydration. But the above fusion can be suppressed by adjusting evaporation conditions to acquire smaller PNIPAM particles which have sufficient mechanical properties to keep their basic particle morphology. Further, by changing evaporation pressure to positive or negative pressure, dehydrated PNIPAM micro/nano-particles with excellent uniformity and separation can be obtained. This work will provide guidance for extracting micro/nano-particles from polymer/diluent systems with LCST. [ABSTRACT FROM AUTHOR]

This article is devoted to the study of the phenomenon of superheating of partially miscible mixtures having a lower critical solution temperature and the thermal effect accompanying the relaxation of an unstable mixture, within the framework of the problem of high-density heat flux removal. The study was carried out by using the method of the controlled pulse heating of a platinum wire probe. The characteristic heating time was from 0.2 to 180 ms. The superheating degree of the mixture relative to the diffusion spinodal exceeded 100 K. The heat flux density from the heater surface reached 13.7 MW/m2. The object of research was an aqueous solution of polypropylene glycol-425 (PPG-425). The obtained results clearly indicate that such mixtures can be used as coolants in processes where the possibility of powerful local heat release cannot be excluded. They also form the basis for expanding the phase diagram by involving in the study not-fully-stable and unstable states of the mixture. [ABSTRACT FROM AUTHOR]

Temperature-responsive polymers are often characterized by an abrupt change in the degree of swelling brought about by small changes in temperature. Polymers with a lower critical solution temperature (LCST) in particular, are important as drug and gene delivery vehicles. Drug molecules are taken up by the polymer in their solvent swollen state below their LCST. Increasing the temperature above the LCST, typically physiological temperatures, results in desolvation of polymer chains and microstructure collapse. The trapped drug is released slowly by passive diffusion through the collapsed polymer network. Since diffusion is dependent on many variables, localizing and control of the drug delivery rate can be challenging. Here, we report a fundamentally different approach for the rapid (seconds) tumor-specific delivery of a biomacromolecular drug. A copolymer nanoparticle (NP) was engineered with affinity for melittin, a peptide with potent anti-cancer activity, at physiological temperature. Intravenous injection of the NP-melittin complex results in its accumulation in organs and at the tumor. We demonstrate that by local cooling of the tumor the melittin is rapidly released from the NP-melittin complex. The release occurs only at the cooled tumor site. Importantly, tumor growth was significantly suppressed using this technique demonstrating therapeutically useful quantities of the drug can be delivered. This work reports the first example of an in vivo site-specific release of a macromolecular drug by local cooling for cancer therapy. In view of the increasing number of cryotherapeutic devices for in vivo applications, this work has the potential to stimulate cryotherapy for in vivo drug delivery. [Display omitted] [ABSTRACT FROM AUTHOR]

Bioinspired thermoresponsive polymers have received increasing attention for many applications. Here, we report a series of thermoresponsive polypeptoid block copolymers containing o‐nitrobenzyl groups, that is, poly(ethylene glycol)‐b‐poly[N‐[2‐[N‐(o‐nitrobenzyloxycarbonyl)‐amino]‐ethyl]‐glycine] (PEG‐b‐PN[oNB]G), prepared by ring‐opening polymerization. The polypeptoid block copolymers show reversible lower critical solution temperature (LCST)‐type behavior in water with tunable phase transition properties dependent on the pH values, chemical compositions, and concentrations of the copolymers. The dynamic light scattering results reveal the formation of spherical micelles and temperature‐induced aggregation of PEG‐b‐PN(oNB)G. Notably, the phase transition of the block copolymer solution upon heating appears extremely sharp (∆T < 1°C), superior to bench mark poly(N‐isopropylacrylamide). In addition, we present the removal of photo‐responsive o‐nitrobenzyl groups can result in the increased clouding point and even the loss of phase transition properties, acting as an excellent regulator to tune the LCST behavior. We demonstrate that the hydrogen‐bonding interaction may play a critical part on the LCST behavior. The prepared diblock copolymers show great potential for many applications and its structure–property may shed light on highly designable stimuli‐responsive polymeric materials. [ABSTRACT FROM AUTHOR]

Stimuli-responsive hydrogels have recently gained interest within shapeshifting applications due to their capabilities to expand in water and their altering swelling properties when triggered by stimuli, such as pH and heat. While conventional hydrogels lose their mechanical strength during swelling, most shapeshifting applications require materials to have mechanical strength within a satisfactory range to perform specified tasks. Thus, stronger hydrogels are needed for shapeshifting applications. Poly (N-isopropylacrylamide) (PNIPAm) and poly (N-vinyl caprolactam) (PNVCL) are the most popular thermosensitive hydrogels studied. Their close-to-physiological lower critical solution temperature (LCST) makes them superior candidates in biomedicine. In this study, copolymers made of NVCL and NIPAm and chemically crosslinked using poly (ethylene glycol) dimethacrylate (PEGDMA) were fabricated. Successful polymerisation was proven via Fourier transform infrared spectroscopy (FTIR). The effects of incorporating comonomer and crosslinker on the LCST were found minimal using cloud-point measurements, ultraviolet (UV) spectroscopy, and differential scanning calorimetry (DSC). Formulations that completed three cycles of thermo-reversing pulsatile swelling are demonstrated. Lastly, rheological analysis validated the mechanical strength of PNVCL, which was improved due to the incorporation of NIPAm and PEGDMA. This study showcases potential smart thermosensitive NVCL-based copolymers that can be applied in the biomedical shapeshifting area. [ABSTRACT FROM AUTHOR]

Responsive materials have garnered increasing attention in the membrane separation field. However, fabricating smart gating membranes with tunable pore sizes to separate complex systems remains challenging. Herein, gating membranes with boroxine skeleton and temperature-tunable pores were successfully fabricated by fixing lower critical solution temperature (LCST)-type organoboron polymers (poly(N-isopropylacrylamide- co -glycidyl methacrylate/3-aminophenylboronic acid), PNG-APBA) onto the membrane surface via "impregnation-dehydration-crosslinking" strategy. The conformational behavior of the NIPAM-containing polymer chains (shrinking above LCST-stretching below LCST) serves as a functional gate, enabling the membranes to achieve reversibly tunable pore sizes and surface properties. The modified membranes exhibit gradient separation capabilities for small/medium/large molecules in complex polymer systems through temperature-tunable channels. The tunable pores also provided a potential tool for the high-selectivity separation of mixed proteins, such as lysozyme (LZM) and hemoglobin (Hb). Notably, the conformational behavior of the polymer chains endowed the membranes with excellent self-cleaning ability (FRR > 99.5 %), while the boroxine network enhanced the grafting stability of the polymer chains, ensuring effective reversibility and repeatability of membranes. [Display omitted] • Smart gating membranes were prepared via an impregnation-dehydration-crosslinking strategy. • The pore size and surface properties of the membranes exhibit thermal-sensitive tunability. • Modified membranes exhibited excellent multimolecular gradient separation capability and self-cleaning performance. • Boroxine endowed membranes with improved grafting stability and thermoresponsive reversibility. [ABSTRACT FROM AUTHOR]

Photothermal nanoparticles can convert absorbed light, particularly in the near-infrared region, into heat, which can be utilized in various applications, including sterilization and wound care. This study developed a thermoresponsive hydrogel composite fabricated using poly(N-isopropylacrylamide) (PNIPAM) and hollow gold nanoparticles (HAuNPs) and evaluated its photothermal performance and sterilization effects under near-infrared irradiation. HAuNPs were synthesized using a galvanic replacement reaction and incorporated into the PNIPAM matrix. The HAuNPs@PNIPAM film demonstrated significant photothermal conversion efficiency, reaching temperatures of 68 and 83.8 °C for 0.018-wt% and 0.036-wt% HAuNP films, respectively. The 0.018-wt% HAuNPs@PNIPAM film completely eradicated E. coli after seven cycles, whereas the 0.036-wt% film achieved an approximately 70 % bacterial reduction in one cycle and full sterilization in two cycles. Furthermore, the film exhibited reversible swelling–shrinkage behavior and maintained thermal stability over repeated cycles. These results suggest that the HAuNPs@PNIPAM film can serve as an effective multifunctional wound dressing material, combining wound contraction and antibacterial properties, with a potentially significant impact on wound care applications. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • Thermoresponsive polymers (TRPs) were synthesized with property characterization. • TRPs were studied for microalgae (Chlorella vulgaris) harvesting. • The physicochemical properties of TRPs affected algae harvesting efficiency. • Using TRPs achieved approx. 92% algae harvesting efficiency. Algal biomass harvesting is one of key technical hurdles impeding the commercialization of algae-based biorefinery. The goal of this work is to develop an innovative technology for algae cell harvesting. Thermoresponsive polymers (TRPs) such as poly(N-isopropylacrylamide) (PNIPAM) and its derivatives were studied on their properties and potential applications for microalgae harvesting. Various PNIPAM was synthesized, and the effects of charge, molecular weight (MW), amine content, and polymer concentration on the polymer phase transition temperature, the degree of phase separation, and the harvesting of microalgae (Chlorella vulgaris) were investigated. The lower critical solution temperature (LCST) of PNIPAM decreased with the increase of polymer concentration, while the decline rate reduced under high MW. The amine content didn't significantly affect the LCST of TRPs. Approx. 92 % of algae cells were harvested by PNIPAM-300 kDa. Modified TRPs showed few benefits in enhancing algae harvesting. TRPs are a promising class of polymers for microalgae harvesting. [ABSTRACT FROM AUTHOR]

All-atom molecular dynamics (MD) simulations are employed to compare the lower critical solution temperature (LCST) behaviors of poly(N-isopropylacrylamide) (PNIPAM) and elastin-like polypeptides (ELPs) with the canonical Val-Pro-Gly-Val-Gly ((VPGVG)n) sequence over a range of temperatures from 280 K to 380 K. Our simulations suggest that the structure of proximal water dictates the conformation of both the (VPGVG)n ELPs and PNIPAM chains. Specifically, the LCST transition in ELPs can be attributed to a combination of thermal disruption of the network of the proximal water near both hydrophilic and hydrophobic groups in the backbone and side-chain of (VPGVG)n, resulting in a reduction in solvent accessible surface area (SASA). This is accompanied with an increase in the secondary structure above its LCST. In the case of PNIPAM, the LCST transition is a result of a combination of a reduction in the hydrophobic SASA primarily due to the contributions of isopropyl side-chain and less to the backbone and the formation of intra-chain hydrogen bonds between the amide groups on the side-chain above its LCST.

Amphiphilic fluorinated copolymers PEGMAx‐co‐FAy and TEGMAx‐co‐FAy are prepared by activators regenerated by electron transfer atom transfer radical polymerization (ARGET‐ATRP). All polymers present a reversible thermoresponsive lower critical solution temperature‐type behavior, and a cloud point temperature (Tc) in the range of 30–60 °C strictly dependent on the length of the oxyethylene side chain, the content of the hydrophobic counits, and the concentration of the solution. Combined small angle X‐ray scattering (SAXS) and dynamic light scattering measurements are used to study the self‐assembly behavior in water, organic solvents (tetrahydrofuran [THF] and dimethylformamide [DMF]), and a fluorinated solvent (hexafluorobenzene [HFB]). SAXS confirms the formation of compact‐globular single‐chain self‐folded unimer micelles in water below Tc, which generally presents small hydrodynamic diameters (Dh ≤ 8 nm) as a result of the folding of the hydrophobic perfluorohexylethyl acrylate counits. The copolymers are also able to form reverse unimer micelle in HFB. The copolymers are not able to self‐assemble in unimer micelles in THF or DMF solutions, in which they adopt conventional random coil conformations. [ABSTRACT FROM AUTHOR]

[Display omitted] The shape and quantity of hydrophilic silica nanoparticles (NPs) can be used to tune the microstructure, rheology, and stability of phase-separating polymer solutions. In thermoresponsive polymer systems, silica nanospheres are well-studied whereas anisotropic NPs have little literature precedent. Here, we hypothesize that NP shape and concentration lower the onset of rheological and turbidimetric transitions of aqueous poly(N-isopropyl acrylamide) (PNIPAM) solutions. Differential scanning calorimetry (DSC), Fourier-transform infrared spectroscopy (FTIR), turbidimetry, and oscillatory rheology are utilized to examine interactions between NPs, PNIPAM, and water and to track changes in phase separation and rheological properties due to NP concentration and shape. NP addition reduces phase separation enthalpy due to PNIPAM-NP hydrogen bonding interactions, the degree to which depends on polymer content. While NP addition minorly impacts thermodynamic and optical properties, rheological transitions and associated rheological properties are dramatically altered with increasing temperature, and depend on NP quantity, shape, and polymer molecular weight. Thus NP content and shape can be used to finely tune transition temperatures and mechanical properties for applications in stimuli-responsive materials. [ABSTRACT FROM AUTHOR]

Infection associated with biomedical implants remains the main cause of failure, leading to reoperation after orthopedic surgery. Orthopedic infections are characterized by microbial biofilm formation on the implant surface, which makes it challenging to diagnose and treat. One potential method to prevent and treat such complications is to deliver a sufficient dose of antibiotics at the onset of infection. This strategy can be realized by coating the implant with thermoregulatory polymers and triggering the release of antibiotics during the acute phase of infection. We developed a multi-layered temperature-responsive polymer brush (MLTRPB) coating that can release antibiotics once the temperature reaches a lower critical solution temperature (LCST). The coating system was developed using copolymers composed of diethylene glycol methyl ether methacrylate and 2-hydroxyethyl methacrylate by alternatively fabricating monomers layer by layer on the titanium surface. LCST was set to the temperature of 38–40 °C, a local temperature that can be reached during infection. The antibiotic elution characteristics were investigated, and the antimicrobial efficacy was tested against S. aureus species (Xen29 ATCC 29 213) using one to four layers of MLTRPB. Both in vitro and in vivo assessments demonstrated preventive effects when more than four layers of the coating were applied, ensuring promising antibacterial effects of the MLTRPB coating. [ABSTRACT FROM AUTHOR]

This article reports the synthesis of poly(N-vinylcaprolactam-co-N-methylolacrylamide) (P(NVCL-co-NMA)) nanogels and investigates their thermo-/pH-responsive behavior. The formation of nanogels was synthesized using free radical emulsion polymerization by varying the monomer composition of NVCL:NMA, and their molecular structure was characterized by 1H-NMR and FTIR. It was found that the nanogels were successfully prepared, and the nanogels exhibited LCST-type phase transition behavior. Cloud point transition temperature (Tc) was studied as a function of copolymer composition, MBA concentration, and pH of the solution by exploring their changes in turbidity using UV–vis spectrophotometer. Our studies reveal that Tc nanogels increased with increasing concentration of NMA, which is due to the hydrophilicity of NMA. Our research also demonstrated that the increase in MBA percentage could decrease the Tc of the synthesized nanogels. Interestingly, P(NVCL-co-NMA) nanogels showed not only a thermoresponsive behavior but also a pH response with increasing Tc in a strong acidic environment owing to the H-bonds within the polymer chains. The results show that nanogels with initial monomer composition of NVCL and NMA of 75% and 25%, respectively, and using 4% of MBA showed Tc around 35°C at pH 7.4. In addition, DLS studies also confirmed this result since the particle sizes became much larger after surpassing the temperature of 35°C. Due to this founding, such nanogels might have potential application in controlled release. Nevertheless, further studies regarding the adjustment of Tc are still needed. [ABSTRACT FROM AUTHOR]

Thermosensitive copolymers P1–P5 of N-isopropylacrylamide (NIPA) and poly(ethylene glycol) methyl ether methacrylates (PEGMEMs) were synthesized via surfactant-free precipitation polymerization (SFPP) using ammonium persulfate (APS) at 70 °C. The polymerization course was evaluated by the conductivity. The hydrodynamic diameters and the polydispersity indexes (PDI) of P1–P5 in the 18–45 °C range, which were assessed via dynamic light scattering (DLS), were at 18° (nm): 26.07 ± 0.54 (PDI 0.65 ± 0.03), 68.00 ± 1.10 (PDI 0.56 ± 0,02), 45.12 ± 0.57 (PDI 0.51 ± 0.03), 62.78 ± 0.40 (PDI 0.53 ± 0.003), and 92.95 ± 1.56 (PDI 0.60 ± 0.04), respectively. The lower critical solution temperatures ranged from 31 to 33 °C. The electrophoretic mobilities estimated the zeta potential in the 18–45 °C range, and at 18 °C, they were (mV): −4.64 ± 1.30, −6.91 ± 2.67, −5.85 ± 3.17, −2.28 ± 0.30, and −3.60 ± 0.96 for P1–P5, respectively. The polymers were characterized by Attenuated Total Reflectance Fourier-Transform Infrared spectroscopy (ATR-FTIR), H nuclear magnetic resonance (1H NMR), thermogravimetric analysis (TGA/DTA), Differential Scanning Calorimetry (DSC), and powder X-ray diffraction analysis (PXRD). Stable amorphous polymers were obtained. We conclude that the length of the co-monomer chain nonlinearly influences the properties of the obtained thermosensitive polymer nanostructures. [ABSTRACT FROM AUTHOR]

With the deepening of the research on the conversion of cellulose biomass to furfural, there is no green and efficient method to separate sugars and 5-HMF. This study utilized a thermoreversible aqueous two-phase system (ATPS) coupled with tetrabutylammonium bromide ([N 4444 ]Br)- based deep eutectic solvents (DES) and inorganic salts for separating glucose and 5-HMF. The thermal characteristics of DESs were analyzed by thermogravimetry (TGA) and differential scanning calorimetry (DSC). The thermoreversible phase behavior of ATPS was determined by phase diagram. Furthermore, the process factors were optimized, such as the type and concentration of DES and phosphate, the temperature, and the time of ATPS were investigated, to maximize the separation of glucose and 5-HMF. Finally, the ATPS was a successful integrated catalytic reaction of glucose involving CrCl 3 and 5-HMF separation. The results showed that the ATPS consist of 30 wt% [N 4444 ]Br-EG and 25 wt% K 2 HPO 4 had the most efficient extraction rate, 5-HMF reached 96.0 ± 0.6%, and mainly existed in the DES phase, while glucose was enriched in salt phase, and the extraction rate reached 99.9 ± 0.03%. And the 5-HMF yield reached 25.6 ± 1.1% in the production separation integrated platform. This thermoreversible ATPS may provide a guide for the effective extraction of furfural from biomass-derived glucose. [Display omitted] [ABSTRACT FROM AUTHOR]

Three series of thermo- and/or pH-responsive polymer-grafted SiO2 nanoparticles, SiO2-graft-poly(oligo(ethylene glycol) methacrylate) (SiO2-g-POEGMA), SiO2-graft-poly(acrylic acid) (SiO2-g-PAA) and SiO2-graft-poly(oligo(ethylene glycol) methacrylate-state-acrylic acid (SiO2-g-P(OEGMA-stat-AA)), were prepared by grafting POEGMA and/or PAA onto the surface of silica nanoparticles through the surface-initiated atom transfer radical polymerization (SI-ATRP). The lower critical solution temperature (LCST) of SiO2-g-POEGMA (MOEGMA = 300 g/mol) was found to be 64 °C. For SiO2-g-PAA nanoparticles, at the pH range from 8 to 12, the hydrodynamic diameter of the nanoparticles increases with increasing pH, and the zeta potential of SiO2-g-PAA nanoparticles is negatively charged and decreases with increasing pH. Owing to the thermo- and pH-responsive, the hydrodynamic diameters of SiO2-g-P(OEGMA-stat-AA) nanoparticles increase with the increasing pH, and the LCSTs of those nanoparticles increase with the increase of POEGMA content. [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]

Abstract The combination therapy based on multifunctional nanocomposites has been considered as a promising approach to improve cancer therapeutic efficacy. Herein, we report targeted multi-functional poly(N-isopropylacrylamide) (PNIPAM)-based nanocomposites for synergistic chemo-photothermal therapy toward breast cancer cells. To increase the transition temperature, acrylic acid (AAc) was added in synthetic process of PNIPAM, showing that the intrinsic lower critical solution temperature was changed to 42 °C . To generate the photothermal effect under near-infrared (NIR) laser irradiation (808 nm), polypyrrole (ppy) nanoparticles were uniformly decorated in PNIPAM-AAc. Folic acid (FA), as a cancer targeting ligand, was successfully conjugated on the surplus carboxyl groups in PNIPAM network. The drug release of PNIPAM-ppy-FA nanocomposites was efficiently triggered in response to the temperature change by NIR laser irradiation. We also confirmed that PNIPAM-ppy-FA was internalized to MDA-MB-231 breast cancer cells by folate-receptor-mediated endocytosis and significantly enhanced cancer therapeutic efficacy with combination treatment of chemo-photothermal effects. Therefore, our work encourages further exploration of multi-functional nanocarrier agents for synergistic therapeutic approaches to different types of cancer cells.

In this study, a simple method was used to synthesize novel thermosensitive hydroxybutyl chitosan oligosaccharide (HBCOS) by introducing hydroxybutyl groups to C6–OH of chitosan oligosaccharide (COS) chain. The variation in light scattering demonstrated that HBCOS had good thermosensitive properties and the particle size of HBCOS changed from 2.21–3.58 to 281.23–4,162.40 nm as the temperature increased to a critical temperature (LCST). The LCST of HBCOS (10 mg/ml) decreased from 56.25°C to 40.2°C as the degrees of substitution (DSs) increased from 2.96 to 4.66. The LCST of HBCOS with a DS of 4.66 decreased to 33.5°C and 30°C as the HBCOS and NaCl concentrations increased to 50 mg/ml and 4% (w/v), respectively. Variable-temperature FTIR spectroscopy confirmed that dehydration of hydrophobic chains and the transition of hydrogen bonds were the driving forces for the phase transition of HBCOS. Moreover, HBCOS was not cytotoxic at different concentrations. This work generated a novel thermosensitive HBCOS with tunable thermoresponsive properties and excellent biocompatibility, which may be a potential nanocarrier for the biomedical application.