Search

Metal‐organic frameworks (MOFs) are considered as an ideal enzyme support because of their porous structural superiority. However, MOFs@enzyme composites have usually compromised their hydrolysis efficiency due to the narrow space inducing unfavourable enzyme conformations. Herein, a thermo‐responsive poly(N,N‐dimethylacrylamide) (PD) was fixed onto the surface of UiO‐66‐NH2 (UiO) through a post‐synthetic modification protocol. Using poly(2‐vinyl‐4,4 dimethylazlactone) (V) as a linker, PVD‐UiO@cellulase composites were fabricated after cellulase was immobilized onto the UiO surface through covalent bonding. The composites conferred favorable cellulase conformations, boosting hydrolysis efficiency and stability, which relied on the soft PVD shell and confinement effect yielded by the curled PVD chains at high temperatures. Compared with free cellulase, the proposed composites exhibited a 33.1‐fold enhancement of the Kcat values at 50 °C. The PVD‐UiO@cellulase composites were applied to the hydrolysis of cellulose in the stalks and leaves of Epipremnum aureum. The results highlight the potential of smart PVD‐UiO@cellulase composites in the hydrolysis of cellulose, affording a valuable platform for the preparation of unique MOFs@enzyme composites and their industrial applications. [ABSTRACT FROM AUTHOR]

Poly(N‐isopropyl acrylamide) (PNIPAm)‐based smart hydrogels are widely employed in emerging applications such as drug delivery and tissue engineering, because their lower critical solution temperature (LCST) is close to physiological conditions. However, the dense chain collapse during the thermo‐responsive phase transition restricts water diffusion, resulting in limited volumetric change. Here, a pure PNIPAm hydrogel that achieves a large‐scale volume transition by incorporating PNIPAm microgels, is presented. During its thermo‐responsive shrinkage, the microgels contract to 10% of their original volume, generating open macropores that serve as efficient water channels, thereby facilitating volume change of hydrogel bulk. In contrast to conventional PNIPAm hydrogels with static porous structures, these dynamic macropores disappear when the microgels return to their initial state at lower temperatures, preserving the mechanical integrity of the entire hydrogel. This enhanced deformability enables the bilayer hydrogel actuator to achieve bending angles exceeding 1150°, a sixfold increase over traditional PNIPAm‐based actuators, allowing it to function as an intelligent gripper capable of capturing small, mobile organisms. This approach, which addresses the inherent challenge of achieving large‐scale deformability in conventional bulk PNIPAm hydrogels, is distinct from existing strategies. [ABSTRACT FROM AUTHOR]

Shape-memory polyester films having functional groups were prepared and further grafted onto poly(N-isopropylacrylamide) (PNIPAAm) via atom-transfer radical polymerization. The grafting point of PNIPAAm was controlled by changing the composition of good and poor solvents. In the case of graft polymerization using only good solvents, the film swells, and polymerization proceeds not only from the surface but also from the internal polymerization initiation points. By increasing the proportion of poor solvents, PNIPAAm was grafted onto the surface of the film without swelling. The samples grafted to the interior regions of the film exhibited a decrease in the shape-memory recovery rate and recovery speed, whereas the samples grafted only to the surface of the film exhibited high shape-memory properties. Furthermore, contact-angle measurements revealed that the surface-grafted polymer exhibited changes in surface properties in response to film deformation. Because the deformation of the film is a large change, on the order of several millimeters, the deformation of the manually stretched film was shown to control molecular-level changes on the surface. [ABSTRACT FROM AUTHOR]

In this work, poly (N-isopropylacrylamide-b-lauryl acrylate) (PNIPAM-b-PLA) as an intelligent polymeric micelle, which is temperature-sensitive, was successfully synthesized via the RAFT polymerization method, allowing precise control over molecular weight. Initially, PNIPAM was synthesized and then applied as a macro chain transfer agent for the polymerization of lauryl acrylate. Subsequently, the block copolymer was decorated with gold nanoparticles (AuNPs) to produce PNIPAM-b-PLA/AuNPs. The catalytic activity of temperature-sensitive Au catalyst was examined in the hydrogenation of p-nitrophenol to p-aminophenol as a model reaction. Notably, the catalytic activity could be modulated during the reduction reaction by adjusting the temperature, below or above the lower critical solution temperature (LCST) of the polymeric micelle. The catalytic activity of this "smart" Au catalyst can be switched "on" and "off" below and above the LCST of the block copolymer, respectively. Furthermore, the catalytic system exhibited efficient recovery for up to five cycles with minimal Au leaching. [ABSTRACT FROM AUTHOR]

In recent times, there has been a significant surge in research interest surrounding thermo-responsive water-soluble polyacrylamides, primarily due to their intriguing capability to undergo significant solubility changes in water. These polymers exhibit the remarkable ability to shift from a soluble to an insoluble state in response to temperature variations. The capacity of these polymers to dynamically respond to temperature changes opens up exciting avenues for designing smart materials with tunable properties, amplifying their utility across a spectrum of scientific and technological applications. Researchers have been particularly captivated by the potential applications of thermo-responsive water-soluble polyacrylamides in diverse fields such as drug delivery, gene carriers, tissue engineering, sensors, catalysis, and chromatography separation. This study reports the construction and functionalization of polymer gels consisting of a polymer network of polyacrylamide derivatives with nano-sized structural units. Specifically, thermo-responsive polymer gels were synthesized by combining well-defined star-shaped polymers composed of polyacrylamide derivatives with a multifunctional initiator and linking method through a self-accelerating click reaction. The polymerization system employed a highly living approach, resulting in polymer chains characterized by narrow molecular weight distributions. The method’s high functionality facilitated the synthesis of a temperature-responsive block copolymer gel composed of N-isopropyl acrylamide (NIPA) and N-ethyl acrylamide (NEAA). The resulting polymer gel, comprising star-shaped block copolymers of NIPA and NEAA, showcases smooth volume changes with temperature jumps.

Stimuli-responsive or smart polymers are macromolecules that can change their physicochemical structure in response to environmental changes such as temperature, pH, UV irradiation, solvent exchange, magnetic field, and ionic factors. Thermo-responsive hydrogels benefit from temperature changes as a trigger for sol-gel transition. They are advantageous for some biomedical applications because they do not require organic solvents, chemical additives, or external fields. Biocompatible and biodegradable polymers that are liquid at room temperature and gel at physiological temperature can be utilized as injectable biomaterials with unique applications in drug delivery, cell encapsulation, and tissue engineering. Therapeutic agents or cells can be incorporated into the sol solution and injected into the target site, forming an in-situ gel with minimal invasiveness and pain. This review summarizes thermoresponsive hydrogels made from natural and synthetic polymers that are used in wound healing. The versatility, simplicity, and convenience of administration, along with the untapped potential of thermo-responsive polymeric materials, make them the most promising interfaces for chemistry and biology in tissue engineering applications. [ABSTRACT FROM AUTHOR]

A near-infrared light-triggered drug delivery system was designed and developed based on the tungsten disulfide nanosheet-coated temperature-sensitive polymer for photo-thermal therapy and letrozole delivery. The synthesized drug vesicle was characterized in terms of surface morphology, size, crystallinity, and thermal behavior using various techniques. Several main factors influencing drug adsorption efficiency were studied, including sample solution pH, contact time, and temperature. Response surface methodology and central composite design were employed to assist in the adsorption condition optimization with reliability. The nonlinear Langmuir isotherm model provided a better fit with the experimental results showing a maximum monolayer sorption capacity of 6.5 mg g−1. The nonlinear pseudo-second-order kinetic model was found to be appropriate for describing the adsorptive kinetics. Release behavior of letrozole as a chemotherapy drug was carried out at two pH levels and two different temperatures. The nanocarrier shows temperature and pH-dependent drug release curves with higher drug release at acidic media (99.37%; T = 45 °C) compared to natural conditions (28.02%; T = 45 °C). The nanocarrier released the drug faster under the near-infrared laser irradiation (80.50%) than without near-infrared laser irradiation (4%). The release of drug from nanocarrier in different environments obeyed the mechanism of non-Fickian diffusion and best fitted to the Korsmeyer–Peppas. [ABSTRACT FROM AUTHOR]

Thermo-responsive diblock copolymer, poly(N-isopropylacrylamide)-block-poly(N-vinylisobutyramide) was synthesized via switchable reversible addition–fragmentation chain transfer (RAFT) polymerization and its thermal transition behavior was studied. Poly(N-vinylisobutyramide) (PNVIBA), a structural isomer of poly(N-isopropylacrylamide) (PNIPAM) shows a thermo-response character but with a higher lower critical solution temperature (LCST) than PNIPAM. The chain extension of the PNVIBA block from the PNIPAM block proceeded in a controlled manner with a switchable chain transfer reagent, methyl 2-[methyl(4-pyridinyl)carbamothioylthio]propionate. In an aqueous solution, the diblock copolymer shows a thermo-responsive behavior but with a single LCST close to the LCST of PNVIBA, indicating that the interaction between the PNIPAM segment and the PNVIBA segment leads to cooperative aggregation during the self-assembly induced phase separation of the diblock copolymer in solution. Above the LCST of the PNIPAM block, the polymer chains begin to collapse, forming small aggregates, but further aggregation stumbled due to the PNVIBA segment of the diblock copolymer. However, as the temperature approached the LCST of the PNVIBA block, larger aggregates composed of clusters of small aggregates formed, resulting in an opaque solution. [ABSTRACT FROM AUTHOR]

The solid-state zinc-ion battery (ZIB) is environmentally friendly, cost effective, and extremely safe, which are essential features for alternative sustainable energy storage systems. Herein, a polymer composite electrolyte (PCE) is successfully developed through a facile solution-casting approach from a thermo-responsive copolymer-based electrolyte and layered ternary carbide (Ti3AlC2). The thermo-responsive copolymer demonstrated synergistic mechanical properties through the addition of an appropriate plasticizer and a zinc salt. This combination suggests that the material possesses thermal self-protection capabilities due to its anti-Arrhenius ionic-conducting behavior. However, parasitic reactions and dendrite formation hindered the achievement of its full potential. The incorporation of Ti3AlC2 or MAX phase can mitigate the above obstacles, enhancing electrochemical performance with excellent flexibility and maintainable self-extinguishing. The solid-state ZIB benefits from the well-designed PCE with the expanding layer interspacing, delivering a remarkably high capacity (336 mAh g−1 at 0.1 A g−1) and energy density of 242 Wh kg−1. This is achieved due to the Ti3AlC2′s ability to immobilize or entrap triflate anions via electrostatic forces. Therefore, the designed PCE is a promising step toward the development of flexible solid electrolytes in ZIBs.

The use of thermoresponsive smart polymers is the need of the hour and a matter of scientific interest in 3D printing applications such as sensors, drug delivery, scaffold manufacturing, tissue engineering, bio-separation, regenerative medicines, and tissue reconstructions. In the last decade, a variety of different thermoresponsive materials and their 3D printing processes have been developed for such applications. So, the novice researchers working in 3D printing of thermoresponsive materials are looking for the collective information of the processing, application, tools, and techniques requirement with future aspects of research. The applications of specific stimuli have been discussed in this paper with their effect on shape change behaviour. This research paper aims to provide state-of-the-art knowledge for the 3D printing of thermoresponsive polymers with knowledge of materials processing, a recent innovation, innovative 3D printing processes used for thermoresponsive materials, materials information of thermoresponsive polymers and targeted applications. The future scope for the 4D printing of thermoresponsive polymers have been provided throughout the manuscript for the extended applications and studies. Also, this study is supported by an innovative case study for the implementation 3D printing process as recycling of thermoresponsive materials for biomedical applications. [ABSTRACT FROM AUTHOR]

Polymer flooding depicts an interesting strategy to improve the enhanced oil recovery (EOR). This work aims with the synthesis of ionic thermo‐responsive copolymers able to be used as rheological modifiers for EOR under harsh conditions (250,000 ppm of NaCl at 150°C). Copolymers composed of different molar ratio of acrylamide, N‐isopropylacrylamide and 2‐acrylamide‐2‐methyl‐1‐propanesulfonic acid were prepared in aqueous media via free radical polymerization at 50°C using 4,4′‐azobis(‐4″‐cyanopentanoic) acid (ACPA) as initiator. Nuclear magnetic resonance analyses demonstrated the structure and molar composition of synthesized copolymers. Rheological measurements performed at different concentration from 1 to 8 wt% demonstrated an increase in the viscosity from 2000 to 600,000 mPa.s. Aqueous mixtures of polymer at 5 wt% and NaCl at different concentration (5, 10, 15, 20, and 25 wt%) was analyzed. Copolymer ([PAM]/[PNIPAM] = 50/50) displayed a phase separation at 15 wt% of NaCl. Solutions of polymer at 5 and 25 wt% of NaCl were heated at 150°C for 72 h. Results revealed both thermal stability and saline tolerance of copolymers [PAM]/[PNIPAM]/[PAMPS‐Na] = 25/25/50, 35/35/30, and 50/0/50 under harsh conditions with the absence of phase separation of the brine polymer solutions. [ABSTRACT FROM AUTHOR]

A highly selective molecularly imprinted polymer (MIP) to 4-Aminopyridine (4-Ap) target was synthesized starting with azobenzene monomers, which cross-linked initiated by 2, 2′‐azobisisobutyronitrile with the ethylene glycol dimethacrylate. The obtained sorbent, comprised of light-thermosensitive functions, was characterized using FTIR and SEM. The product was finally employed for the 4-AP target in solid-phase extraction. The effect of optimal parameters in the process was studied. The adsorption and release processes for 4-Ap drug delivery were investigated under various conditions, including temperature and radiation wavelengths. This study suggests a facile determination method high selectivity to 4-Ap adsorption/release in a real sample. [ABSTRACT FROM AUTHOR]

This paper introduces a new class of amphiphilic block copolymers created by combining two polymers: polylactic acid (PLA), a biocompatible and biodegradable hydrophobic polyester used for cargo encapsulation, and a hydrophilic polymer composed of oligo ethylene glycol chains (triethylene glycol methyl ether methacrylate, TEGMA), which provides stability and repellent properties with added thermo-responsiveness. The PLA-b-PTEGMA block copolymers were synthesized using ring-opening polymerization (ROP) and reversible addition–fragmentation chain transfer (RAFT) polymerization (ROP-RAFT), resulting in varying ratios between the hydrophobic and hydrophilic blocks. Standard techniques, such as size exclusion chromatography (SEC) and 1H NMR spectroscopy, were used to characterize the block copolymers, while 1H NMR spectroscopy, 2D nuclear Overhauser effect spectroscopy (NOESY), and dynamic light scattering (DLS) were used to analyze the effect of the hydrophobic PLA block on the LCST of the PTEGMA block in aqueous solutions. The results show that the LCST values for the block copolymers decreased with increasing PLA content in the copolymer. The selected block copolymer presented LCST transitions at physiologically relevant temperatures, making it suitable for manufacturing nanoparticles (NPs) and drug encapsulation-release of the chemotherapeutic paclitaxel (PTX) via temperature-triggered drug release mechanism. The drug release profile was found to be temperature-dependent, with PTX release being sustained at all tested conditions, but substantially accelerated at 37 and 40 °C compared to 25 °C. The NPs were stable under simulated physiological conditions. These findings demonstrate that the addition of hydrophobic monomers, such as PLA, can tune the LCST temperatures of thermo-responsive polymers, and that PLA-b-PTEGMA copolymers have great potential for use in drug and gene delivery systems via temperature-triggered drug release mechanisms in biomedicine applications. [ABSTRACT FROM AUTHOR]

Photothermal therapy has been extensively studied to improve the light-to-heat efficiency for tumor ablation, but could cause severe damage to adjacent healthy tissue due to the thermal transfer, the random distribution of photothermal agents (PTAs), or combination hereof. Herein, we solve this dilemma with a material design strategy to develop a P(AAm- co -AN)- b -P(NIPAM- co -DMAa)- b -P(AAm- co -AN) ABA triblock copolymer by RAFT polymerization, which exhibits both UCST and LCST dual thermo-responsive behaviors in aqueous solution. The P(AAm- co -AN) block with appropriate AN content allows to finely tune its UCST to ∼ 43°C, which can effectively co-assemble with camptothecin (CPT) and Cy7-TCF, a near-infrared (NIR) PTA, realizing the photo-activated "on-demand" release of CPT and Cy7-TCF. The LCST of P(NIPAM- co -DMAa) segment is adjusted to ∼ 53°C by varying DMAa content, enabling an irreversible sol-to-gel transition. The heat transfer in hydrogel and heat dissipation at the interface of hydrogel-adjacent tissue are limited, resulting in selectively cell killing in tumor, with little hyperthermia in adjacent tissues. Moreover, the hydrogel continues to release CPT to enhance the synergistic efficacy of PTT with chemotherapy. These results suggest that dual thermo-responsive polymer can contribute PTT with high selectivity and negligible side effects for precise medicine. Photothermal therapy exploits the susceptibility of tumor cells toward external light-induced hyperthermia, but can cause severe damage to adjacent healthy tissue due to thermal transfer, random distribution of photothermal agents (PTAs), or combination hereof. Here, we solve this dilemma by developing a P(AAm- co -AN)- b -P(NIPAM- co -DMAa)- b -P(AAm- co -AN) triblock copolymer with UCST and LCST dual thermo-responsive behaviors, realizing the sequential micelle-unimer-hydrogel phase transitions. The polymer can effectively encapsulate PTA/drug, achieve long systemic circulation, accumulate in tumor through EPR effect, regulate drug release by controlling tumor temperature above UCST via irradiation, and finally exhibit a sol-gel transition, eradicating the heat transfer to adjacent tissue. This represents a practicable strategy to guide the design of next-generation polymeric vector that can contribute PTT with negligible side effects. [Display omitted] [ABSTRACT FROM AUTHOR]

Fluid control on a paper channel is necessary for analysis with multiple reagents, such as enzyme-linked immunosorbent assay (ELISA) in microfluidic paper-based analytical devices (µPADs). In this study, a thermo-responsive valve was fabricated by polymerizing N-isopropylacrylamide on a PVDF porous membrane by plasma-induced graft polymerization. The polymerized membrane was observed by scanning electron microscopy (SEM), and it was confirmed that more pores were closed at temperatures below 32 °C and more pores were opened at temperatures above 32 °C. Valve permeability tests confirmed that the proposed polymerized membrane was impermeable to water and proteins at temperatures below 32 °C and permeable to water at temperatures above 32 °C. The valve could also be reversibly and repeatedly opened and closed by changing the temperature near 32 °C. These results suggest that plasma-induced graft polymerization may be used to produce thermo-responsive valves that can be opened and closed without subsequent loss of performance. These results indicate that the thermo-responsive valve fabricated by plasma-induced graft polymerization could potentially be applied to ELISA with µPADs. [ABSTRACT FROM AUTHOR]

This article overviews the polymer chemistry of acrylates designed for functional-group synergy among the vinyl group and ester- and α-substituents. α-Substituents have been incorporated to tune the reactivity of the vinyl group; for example, ethyl α-cyanoacrylate, known as instant adhesions, has high reactivity to initiate anionic polymerization using moisture. Moreover, α-acyloxyacrylates undergo radical polymerization, increasing the degree of polymerization in proportion to monomer conversions due to the stabilized radical species by the captodative effect. α-Arylacrylates produced alternating copolymers with methyl methacrylate (MMA) using anionic polymerization, which exhibited specific fluorescence. α-(Aminomethyl)acrylates stabilized by intramolecular hydrogen bonding yielded a pH-/thermo-responsive polymer. Anionic polymerization of α-(alkoxymethyl)acrylates resulted in high isotacticity due to the chelating effect at the propagating chain end. α-(Halomethyl)acrylates underwent a nucleophilic conjugate substation reaction, applied to end-functionalization, polycondensation, and polymer degradation. For a long time, ring-opening polymerization of cyclic acrylates has been considered difficult; however, it was recently achieved using sophisticated monomer design. [ABSTRACT FROM AUTHOR]

Thermo-responsive poly (N-isopropylacrylamide) (PNIPAM) polymer has been synthesized by free radical addition polymerization method. The chemical structure of the synthesized polymer has been clarified by FTIR spectroscopy and 1H NMR analyses. Turbidity test shows that the synthesized polymer exhibits thermo-responsive properties, depending on change in temperature. Its lower critical solution temperature (LCST) value is measured as 31°C by DSC analysis. The PNIPAM polymer is then applied onto the cotton fabric in two different concentrations using double-bath impregnation method. Change in hydrophilic character of the fabric, which is temperature dependent, has been revealed by drop and absorption capacity tests, contact angle measurement and surface energy calculation. The test results show that the fabrics exhibit thermoresponsive behavior. Their hydrophilic character is turned to the hydrophobic character above LCST of the polymer. The water vapor permeability of the polymer treated fabrics at temperatures above LCST increases as compared to the untreated fabric due to the increase in fabric porosity. Below LCST, water vapor permeability is increased because of the increasing hydrophility. Consequently, it is concluded that the water vapor permeability of the fabrics can be controlled by changing the temperaturedependent hydrophilic/hydrophobic characteristic and porosity, resulting from swelling or shrinkage of the polymer molecules. [ABSTRACT FROM AUTHOR]

[Display omitted] • Recyclable aqueous two-phase systems were constructed using EO 30 PO 70 and P ADB5.22. • Phase formation mechanism have been studied using Low-field NMR. • Lincomycin was better partitioned with partition coefficient of 5.94. • The recoveries of EO 30 PO 70 and P ADB5.22 reached 95.51 % and 96.18 %, respectively. Aqueous two-phase systems (ATPS) have been widely used in the laboratory separation and purification of antibiotics. However, its large-scale application is limited due to the difficulty in the recovery of the phase-forming polymers. In this study, we aimed to develop a thermo-pH responsive recyclable ATPS using thermo-responsive polymer EO 30 PO 70 and pH-responsive polymer P ADB5.22 for lincomycin partition. This ATPS can rapidly form two-phase interface in less than 5 min and can sustainably be reused. The phase separation mechanism was studied by low-field nuclear magnetic resonance (LF-NMR) and surface tension. The effects of polymer concentration, lincomycin content, pH, temperature and salts type and concentrations on lincomycin partition were investigated. The 25 % (w/v) EO 30 PO 70 /4.5 % (w/v) P ADB5.22 ATPS showed good partitioning at room temperature for lincomycin fermentation broth in the presence of 80 mM LiCl at pH 9.1, with a partition coefficient of 5.94 and extraction recovery of 94.68 %. In addition, the recycling of the two polymers showed a high efficiency, with 95.51 % and 96.18 % recoveries of EO 30 PO 70 and P ADB5.22 after four cycles, respectively. This recyclable ATPS has a promising industrial application in the separation and purification of antibiotics. [ABSTRACT FROM AUTHOR]

[Display omitted] • Thermo-responsive Si-PM-PN particles are engineered to tailor coffee-ring effect. • Si-PM-PN particles move inward along the droplet interface above the LCST of PNIPAM. • Coffee-ring effect is effectively mitigated by utilizing thermo-responsive polymers. Silica (Si) particles coated with poly(methyl methacrylate- b - N -isopropylacrylamide) (PMMA- b -PNIPAM) block copolymers (Si-PM-PN particles) were engineered to mitigate the coffee-ring effect (CRE) frequently encountered during the drying process of particulate suspensions. Leveraging the thermo-responsive transition between the hydrophilic and hydrophobic states of PNIPAM, with its lower critical solution temperature (LCST) around 32 °C, enabled precise adjustment of the CRE. Through microrheological analysis using multi-speckle diffusing wave spectroscopy and observation under an optical microscope, the dynamic behaviors of Si-PM-PN particles in sessile suspension droplets during drying were scrutinized both below and above the LCST. Above the LCST, the Si-PM-PN particles exhibited hydrophobic characteristics, with some migrating toward the center along the droplet interface, resulting in a more uniform particle distribution post-drying. Conversely, below the LCST, the homogeneously dispersed Si-PM-PN particles displayed rapid Brownian motion, contributing to a pronounced CRE. This approach, involving the surface treatment of particles with thermo-responsive polymers, effectively altered the droplet pattern by modulating particle interactions with the air–water interface. [ABSTRACT FROM AUTHOR]

In the field of stimuli-responsive polymer research, poly-N-isopropylacrylamide (PNIPAAm) has been widely studied, because this material has unique properties which respond to temperatures near to that of the human body, approximately 36 °C. In this study, a nano-patterned PNIPAAm hydrogel was prepared using UV-irradiation and soft lithography. Chemical changes in the C–C double bonds of the PNIPAAm hydrogel were confirmed by FT-IR analysis. The thermal properties of the hydrogel were analyzed by differential scanning calorimetry (DSC), which confirmed its low critical solution temperature (LCST). The highest gel content of approximately 46% was achieved at 120 min UV-irradiation. The nano-patterned morphology of the PNIPAAm hydrogel exhibited temperature-dependent reversible shape transformation. This study shows that the reversible shape transformation of the PNIPAAm hydrogel was due to swelling and shrinking. [ABSTRACT FROM AUTHOR]

Fluid control on a paper channel is necessary for analysis with multiple reagents, such as enzyme-linked immunosorbent assay (ELISA) in microfluidic paper-based analytical devices (µPADs). In this study, a thermo-responsive valve was fabricated by polymerizing N-isopropylacrylamide on a PVDF porous membrane by plasma-induced graft polymerization. The polymerized membrane was observed by scanning electron microscopy (SEM), and it was confirmed that more pores were closed at temperatures below 32 °C and more pores were opened at temperatures above 32 °C. Valve permeability tests confirmed that the proposed polymerized membrane was impermeable to water and proteins at temperatures below 32 °C and permeable to water at temperatures above 32 °C. The valve could also be reversibly and repeatedly opened and closed by changing the temperature near 32 °C. These results suggest that plasma-induced graft polymerization may be used to produce thermo-responsive valves that can be opened and closed without subsequent loss of performance. These results indicate that the thermo-responsive valve fabricated by plasma-induced graft polymerization could potentially be applied to ELISA with µPADs.

Abstract Background The recovery characteristics of phase-forming polymers are essential for aqueous two-phase systems (ATPS) to recycle in bioseparation engineering. Results A new thermo-responsive copolymer (P VBAm) is suggested based on N-vinylcaprolactam, acrylamide, and butyl methacrylate. Together with another thermo-responsive polymer, poly (N-isopropyl acrylamide) (P N), it has been applied to form a recyclable ATPS. P VBAm and P N were designed to obtain structures and molecular weights allowing a lower critical solution temperature (LCST). By polymerization optimization, both P N and P VBAm were obtained with recoveries 98.5% and 95% above their LCST (i.e., P N 32.5 °C and P VBAm 40.5 °C), respectively, which allows each ATPS phase to be effectively recycled. The recycled ATPS based on P VBAm and P N was applied to the partitioning of vitamin B12. Under optimized conditions (5% PVBAm/3.5 %PN ATPS, in the presence of 0.8 M KCl, pH 4.0), the partition coefficient of vitamin B12 reached a value of 5.81. Conclusion The new ATPS based on the thermo-responsive copolymer P VBAm/P N possessed appropriate recycling characteristics regarding LCST, as well as recovery and phase separation characteristics.

Thermo-responsive textiles with moisture/thermal management characteristics have attracted extensive attention for the purpose of improving human comfort or special job requirements. In this study, a thermo-responsive cotton (TR-cotton) fabric for moisture/thermal management was prepared by horseradish peroxidase/acetylacetone (ACAC)/hydrogen peroxide (H2O2)-initiated "graft from" polymerization on the fiber surface. Enzymatic graft polymerization is a new environmentally friendly method to prepare thermo-responsive textiles. Diethylene glycol monomethyl ether methacrylate (MEO2MA) and poly(ethylene glycol) methyl ether methacrylate (OEGMA500) were selected as thermosensitive monomers for graft copolymerization. The lower critical solution temperature (LCST) of P(MEO2MA-co-OEGMA500) was 29 °C. TR-cotton was hydrophilic at ambient temperature below the LCST and hydrophobic at a temperature above the LCST. The air/moisture permeability of TR-cotton at a high temperature (> LCST) was better than that at a low temperature (< LCST). In a cold environment, the fabric exhibited a heat preservation effect (~ 1.5 °C warmer than that observed for unmodified cotton fabric). This study could provide an enzyme catalysis method for the development of "smart textiles". [ABSTRACT FROM AUTHOR]

The recyclable aqueous two-phase systems (ATPS) responding to environmental stimuli have been widely studied in the purification of biologics. In this study, a thermo-responsive polymer PNE was copolymerized after optimization of monomer ratio. In addition, its lower critical solution temperature (LCST, 31 °C) and first recovery (99.43%) were determined. Then, PNE was used to form two recyclable ATPS with another thermo-responsive polymer PNDBN and a pH-responsive polymer PADB4.91, which were polymers already prepared in the lab. Meanwhile, the partition behavior of microbial transglutaminase (MTG) was explored using these two ATPS. The result showed that the PNE/PADB4.91 ATPS was superior to PNDBN/PNE ATPS owing to its faster phase formation and better partition performance. In order to optimize the partition behavior, several parameters were investigated based on PNE/PADB4.91 ATPS. In the ATPS constructed with 2.5% (w/v) PNE and 3.5% (w/v) PADB4.91, the maximal partition coefficient (1/KE) and enzymatic recovery (ERB) of MTG were 12.9 and 95.21% in the presence of 10 mM KCl when the temperature, pH, and the addition amount of MTG were 25 °C, 7.0, and 2 mg/mL, respectively. [ABSTRACT FROM AUTHOR]

Thermo-responsive polymer films have enabled the development of various functional surfaces with switchable interfacial properties. Assessing the surface forces and friction on such films is of paramount importance. On the one hand, it allows us to extract a great deal of information on the interfacial properties of the films, e.g., adhesiveness and lubricity, and how they could be tuned using different stimuli. On the other hand, surface force measurements complement other thin-film analysis methods, e.g., ellipsometry, to better perceive the correlation between the molecular properties of the polymer chains and the interfacial properties of the film. On this basis, we will, herein, provide a concise review of some recent studies on surface forces and friction tuned by thermo-responsive polymer films. This outline comprises a summary of several research works addressing the effects of temperature, solvent composition, and salts on surface forces and friction. In the end, we briefly discuss a few select studies in which the regulation of surface forces by thermo-responsive polymers is examined with an emphasis on the potential applications. Image 1 [ABSTRACT FROM AUTHOR]

Membrane technology is commonly used to treat wastewater in the food industry. However, membrane fouling remains a major problem. This research aims to study the development of composite membranes with antibacterial properties and self-cleaning ability to solve the membrane fouling problem for fish ball industrial wastewater treatment. Polyethersulfone (PES) membrane was modified with poly(N-isopropyl acrylamide) (PNIPAM), sodium acrylate (SA), and [2-(methacryloyloxy)ethyl]trimethylammonium chloride (DMC), followed by adsorbing silver nanoparticles (AgNPs) onto the membrane surface. The results demonstrate that PNIPAM-SA and PNIPAM-DMC hydrogels at 100-0, 90-10, and 80-20 concentration ratios exhibit thermo-responsive properties. This thermo-responsive effect facilitates the self-cleaning of the membrane at 40 °C (higher than LCST). PES/PNIPAM-SA (80-20) membrane modified with AgNPs exhibited the highest antibacterial properties. For BSA filtration, it was found that the PES/PNIPAM-SA/Ag membrane had a flux that was twice as high as that of the PES/PNIPAM-DMC/Ag membrane. For the filtration of fish ball industrial wastewater, the PES/PNIPAM-SA/Ag membrane is capable of reducing COD, BOD, TKN, and TSS values by 96.64%, 98.13%, 74.68%, and 70.48% respectively. The wastewater quality of permeate passed the standard requirements. Membranes with self-cleaning and antibacterial properties are good candidates to develop for use in further wastewater treatment. [Display omitted] • PES/PNIPAM-SA (80-20) membrane modified with AgNPs exhibited the highest antibacterial properties. • The thermo-responsive effect facilitates the self-cleaning of the membrane at 40 °C. • Modified membrane with SA had a higher BSA flux compared to modified membrane with DMC. • The modified membrane can reduce COD, BOD, TKN, and TSS values by 96.64%, 98.13%, 74.68%, and 70.48%, respectively, for fish ball industrial wastewater filtration. [ABSTRACT FROM AUTHOR]

The combination of natural and synthetic polymers to form hybrid hydrogels offers the potential of fabricating new materials that possess a combination of properties resulting from both types of polymer classes. Within this work, two alkene-functionalized poly(2-alkyl/aryl–2-oxazoline) (PAOx) copolymers and one gelatin derivative, thiolated gelatin (gel-SH), are synthesized as precursors for hybrid hydrogels through a photo-induced radical thiol-ene crosslinking process. In-situ photo-rheology revealed an increased mechanical stability for hydrogels that possess an excess amount of PAOx precursor. A final qualitative investigation of the thermo-responsive properties of a P(EtOx270–norbornenOx30):gel-SH (2:1) hydrogel film revealed a cloud point temperature (Tcp) in the same range as the Tcp of the P(EtOx270–norbornenOx30) polymer precursor, which is around 30 °C. This promising result demonstrates that thermo-responsive hybrid poly(2-oxazoline)-gelatin hydrogels could be prepared with predictable Tcps and that further investigation into this appealing feature might be of interest. Ultimately, this work shows a proof-of-concept of using PAOx as potential hybrid hydrogel precursor in combination with cell-interactive gelatin derivatives to potentially improve the mechanical stability of the final scaffolds and introduce additional features such as thermo-responsiveness for the purpose of drug delivery.

Specific ion effects in aqueous polymer solutions have been under active investigation over the past few decades. The current state-of-the-art research is primarily focused on the understanding of the mechanisms through which ions interact with macromolecules and affect their solution stability. Hence, we herein first present the current opinion on the sources of ion-specific effects and review the relevant studies. This includes a summary of the molecular mechanisms through which ions can interact with polymers, quantification of the affinity of ions for the polymer surface, a thermodynamic description of the effects of salts on polymer stability, as well as a discussion on the different forces that contribute to ion–polymer interplay. Finally, we also highlight future research issues that call for further scrutiny. These include fundamental questions on the mechanisms of ion-specific effects and their correlation with polymer properties as well as a discussion on the specific ion effects in more complex systems such as mixed electrolyte solutions. [ABSTRACT FROM AUTHOR]

Background/Aims: Different approaches have been considered to improve heart reconstructive medicine and direct delivery of pluripotent stem cell-derived cardiomyocytes (PSC-CMs) appears to be highly promising in this context. However, low cell persistence post-transplantation remains a bottleneck hindering the approach. Here, we present a novel strategy to overcome the low engraftment of PSC-CMs during the early post-transplantation phase into the myocardium of both healthy and cryoinjured syngeneic mice. Methods: Adult murine bone marrow mesenchymal stem cells (MSCs) and PSC-CMs were co-cultured on thermo-responsive polymers and later detached through temperature reduction, resulting in the protease-free generation of cell clusters (micro-tissues) composed of both cells types. Micro-tissues were transplanted into healthy and cryo-injured murine hearts. Short term cell retention was quantified by real-time-PCR. Longitudinal cell tracking was performed by bioluminescence imaging for four weeks. Transplanted cells were further detected by immunofluorescence staining of tissue sections. Results: We demonstrated that in vitro grown micro-tissues consisting of PSC-CMs and MSCs can increase cardiomyocyte retention by >10-fold one day post-transplantation, but could not fully rescue a further cell loss between day 1 and day 2. Neutrophil infiltration into the transplanted area was detected in healthy hearts and could be attributed to the cellular implantation rather than tissue damage exerted by the transplantation cannula. Injected PSC-CMs were tracked and successfully detected for up to four weeks by bioluminescence imaging. Conclusion: This approach demonstrated that in vitro grown micro-tissues might contribute to the development of cardiac cell replacement therapies. [ABSTRACT FROM AUTHOR]

Thermo-responsive polymers have attracted much attention in recent years because they can provide a variety of applications for smart devices, but the lack of sufficient mechanical properties and late response rate of the polymers limit their applications. In the current work, we fabricated polymer nanocomposites made from poly(vinyl methyl ether) and nanofillers with photothermal conversion property such as graphene oxide, antimony tin oxide nanoparticles, and silver nanoplates. The prepared nanocomposites showed rapidly reversible and reliable transparent-opaque transitions during the repeated heating and cooling processes, suggesting that they can be applied to smart window applications. [ABSTRACT FROM AUTHOR]

• Crosslinking of chitosan oligomer by a di-aldehyde produces CrCs microparticle. • Modified magnetite nanoparticles were covalently deposited on CrCs microparticle. • PNIPAm copolymer was reacted with remained sites of magnetite nanoparticles. • By core de-crosslinking, two-face Janus nanovehicle was synthesized. • Doxorubicin molecules were chemically linked to nanovehicles via imine reaction. In this study, we developed a novel method to fabricate "Janus" nanoparticles with asymmetric surface chemistry through masking method in three steps which included the covalent deposition of modified magnetic iron oxide nanoparticles on the crosslinked substrate, modification of unprotected site with P(NIPAm-co-NMA) and then removing of the crosslinkages of the substrate. In continuum, the "mixed" nanoparticles with homogeneous surface chemistry were prepared through one-pot reaction of modified iron oxide nanoparticles with chitosan and P(NIPAm-co-NMA). In this process, the two types of polymers were simultaneously reacted with the surface of modified iron oxide nanoparticles. Both nanoparticles were reacted with Doxorubicin via imine reaction. The in vitro release was performed at two temperatures (37 and 40 °C) and pH values (5.8 and 7.4). Results of the comparison between the two formulations revealed that the Janus nanoparticles provided the more controllable release rather than the mixed ones. In addition, rat C6 glioma cells and OLN-93 cells were used to evaluate the cell cytotoxicity at 37 °C, the results demonstrated that Dox-loaded Janus nanoparticles had the desirable performance in inhibition of cancerous cells while they had less toxicity for normal cells rather in comparison to the Dox-loaded mixed ones. [ABSTRACT FROM AUTHOR]

Organic fouling causes the filtration property and serve life decrease of the PVDF membrane and is the challenge for filtration applications. Therefore, it is an urgency desire to construct a PVDF membrane with good filtration and antifouling for researchers. To this end, a based PVDF and poly(N-isopropyl acrylamide)(PNIPA) semi-interpenetrating network polymer was synthesized and used as membrane matrix for preparing semi-interpenetrating network/block copolymers blend membrane. The membrane composition, structure and performance were systematically characterized and investigated by FTIR spectrum, XPS, SEM, contact angle instrument and the other experimental techniques etc. Results indicate that the prepared membrane contains PVDF, PNIPA and block copolymer poly(ethylene oxide)-b-poly(propylene oxide)-b- poly(ethylene oxide) (F127) components, shows a porous cross section comprising a thin top surface layer with small pores, a finger-shape lower layer and a sponge-shape pore bottom layer. When the membrane are used for the filtration of bovine serum albumin(BSA) in aqueous solution at 25 ℃, the rejection can exceed 95.0% at a high flux of 307 L/(m2·h·bar). Simply raising filtration temperature to 60 °C, the flux can reach 606 L/(m2·h·bar) while the rejection barely changes, significantly improving the filtration ability of the membrane. Furthermore, the flux can recover above 93% of the original value after a BSA filtration and a subsequent water washing. Undoubtedly, the prepared membrane displays great potential for filtering BSA aqueous solution and the reason can be ascribed to the synergy between PNIPA and F127 of the membrane. [Display omitted] • PVDF membrane is prepared from semi-interpenetrating network and block copolymers. • High filtration flux and high rejection are obtained simultaneously. • Excellent antifouling is obtained by the introduction of block copolymers. • Filtration ability can be enhanced by simply raising filtration temperature. [ABSTRACT FROM AUTHOR]

Although poly (ether ether ketone) (PEEK) exhibits excellent solvent resistance, it could not be prepared directly by non-solvent induced phase separation (NIPS) method due to its poor solubility. Herein, PEEK porous membranes were successfully fabricated by combining NIPS and acid hydrolysis. The superhydrophilic thermo-responsive poly (N-isopropylacrylamide) (PNIPAm) polymer was in-situ grafted on the PEEK membrane surface via the UV grafting polymerization and improved the membrane interface hydrophilicity, making the membrane water contact angle changed from 89.5° to 0° at 25 °C. After heating the membrane surface to 40 °C, the membrane exhibited hydrophobicity (100°), realizing the thermo-responsiveness via switching the temperature. Furthermore, due to the transferred membrane wettability at different temperatures, PEEK-g-PNIPAm could separate different types of oil-bearing systems with high rejection above 99.0 %. What's more, the PNIPAm layer also enhanced the membrane anti-fouling capacity. Benefiting from the extraordinary solvent resistance of the PEEK matrix, PEEK-g-PNIPAm maintains its intact morphology after 6 h immersion in various organic solvents, addressing the commonly reported problem of polymer membranes having certain solubility in solvents. The PEEK-based membranes with excellent solvent resistance could be useful in the oil-bearing separation. [Display omitted] • PEEK membranes were fabricated via the combination of NIPS and acid treatment. • Facile UV polymerization was proposed for fabricating PEEK-g-PNIPAm membranes. • PEEK-g-PNIPAm membranes exhibited thermo-responsiveness by switching temperature. • PEEK-g-PNIPAm membranes could separate different types of oil-bearing systems. • The PEEK separation membranes featured benign solvent resistance. [ABSTRACT FROM AUTHOR]

In this manuscript, we present a novel computational method to quantify the responsive behaviors of thermo-responsive polymers, focusing on the specific case of Poly-N-isopropyl acrylamide (PNIPAm). By considering both structural parameters (excess entropy) and dynamic properties (diffusivity), we precisely estimate Lower Critical Solution Temperature (LCST) for the NIPAm monomer-water system at varying NIPAm fractions. Our approach, validated through all-atom Molecular Dynamics simulations, successfully reproduces the LCST within the concentration range of 0.17–0.25 mol fractions. This work contributes to a deeper understanding of the responsive behavior of polymers and has implications for improving their applications in different fields, such as cell engineering and protein attachment. [Display omitted] Poly- N -isopropyl acrylamide (PNIPAM) is a widely studied thermo-responsive polymer with unique properties and numerous applications, including cell engineering and protein attachment. However, quantifying the responsive behavior of such polymers is challenging due to the vast configurational space. Existing methods for quantification are either focused on dynamic properties or structural properties, but the changes in structural parameters are small, while those in dynamic properties are significantly larger. This study proposes a new computational method considering non-equilibrium-activity-driven segregation to quantify responsive behaviors using structure (excess entropy) and dynamic (diffusivity) properties. We have calculated the Lower Critical Solution Temperature (LCST) for the N -Isopropyl propionamide (NIPPAm) -water system for different solute fractions by scaling excess entropy with diffusivity obtained by performing all-atom Molecular Dynamics simulations. Our method can precisely reproduce the LCST temperature in the 0.17–0.25 mol fraction concentration range. This approach can be used to study the responsive behavior of other polymers at different stimuli and improve our understanding of their applications. [ABSTRACT FROM AUTHOR]

Foodborne pathogens are a major concern for public health. We demonstrate for the first time a partially automated sensing system for rapid (~17 min), label-free impedimetric detection of Escherichia coli spp. in food samples (vegetable broth) and hydroponic media (aeroponic lettuce system) based on temperature-responsive poly(N-isopropylacrylamide) (PNIPAAm) nanobrushes. This proof of concept (PoC) for the Sense-Analyze-Respond-Actuate (SARA) paradigm uses a biomimetic nanostructure that is analyzed and actuated with a smartphone. The bio-inspired soft material and sensing mechanism is inspired by binary symbiotic systems found in nature, where low concentrations of bacteria are captured from complex matrices by brush actuation driven by concentration gradients at the tissue surface. To mimic this natural actuation system, carbon-metal nanohybrid sensors were fabricated as the transducer layer, and coated with PNIPAAm nanobrushes. The most effective coating and actuation protocol for E. coli detection at various temperatures above/below the critical solution temperature of PNIPAAm was determined using a series of electrochemical experiments. After analyzing nanobrush actuation in stagnant media, we developed a flow through system using a series of pumps that are triggered by electrochemical events at the surface of the biosensor. SARA PoC may be viewed as a cyber-physical system that actuates nanomaterials using smartphone-based electroanalytical testing of samples. This study demonstrates thermal actuation of polymer nanobrushes to detect (sense) bacteria using a cyber-physical systems (CPS) approach. This PoC may catalyze the development of smart sensors capable of actuation at the nanoscale (stimulus-response polymer) and macroscale (non-microfluidic pumping).

Carbon dots (CDs), the youngest member in the carbon nanomaterial family, have drawn considerable attention due to their interesting optical, physicochemical and electronic properties as well as broad promising applications. Here, we developed a facile and effective strategy for the preparation of Au nanoparticles stabilized by thermo-responsive poly(N-isopropylacrylamide) (PNIPAM) functionalized carbon dots (Au@CD@P) under the gentle water media. The as-designed dopamine(DA)-terminated PNIPAM can be easily anchored to CDs via mussel-inspired chemistry route. Both CD@P and CDs could well stabilize the Au nanoparticles with interesting assembled structure. The as-prepared Au@CD and Au@CD@P nanohybrids with good dispersibility and stability exhibited the intriguing catalytic activity for reduction of p -nitrophenol ( p -NP). Especially, Au@CD@P as catalyst also played a switching role in regulating the catalytic rate by temperature. In addition, Au@CD@P exhibited excellent recyclability which may have potential in green chemical industry for developing high-activity catalysts and easy production methods. [ABSTRACT FROM AUTHOR]

Abstract: A thermoresponsive Poly(N‐isopropylacrylamide) (PNIPAAm)‐modified nylon membrane was fabricated via hydrothermal route. Combining rough structure, proper pore size, and thermoresponsive wettability, the membrane can separate at least 16 types of stabilized oil‐in‐water and water‐in‐oil emulsions at different temperatures. Below the LCST (ca. 25 °C), the material exhibits hydrophilicity and underwater superoleophobicity, which can be used for the separation of various kinds of oil‐in‐water emulsions. Above the LCST (ca. 45 °C), the membrane shows the opposite property with high hydrophobicity and superoleophilicity, and it can then separate stabilized water‐in‐oil emulsions. The material exhibits excellent recyclability and high separation efficiency for various kinds of emulsions and the hydrothermal method is facile and low‐cost. The membrane shows good potential in real situations such as on‐demand oil‐spill cleanup, industrial wastewater treatment, remote operation of oil/water emulsion separation units, and fuel purification. [ABSTRACT FROM AUTHOR]

Copyright of Kobunshi Ronbunshu is the property of Society of Polymer Science and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Despite the fact that some progress has been made in the self-assembly of H-shaped polymers, the corresponding self-assemblies that respond to external stimulus and are further utilized to adjust the release of drugs are still deficient. The stimuli-responsive segments with amphiphilic H-shaped structure are generally expected to enhance the controllability of self-assembly process. The synthesis and self-assembly behavior of thermo-responsive amphiphilic H-shaped polymers with poly(ethylene glycol) (PEG), polytetrahydrofuran (PTHF) and poly(N-isopropyl acrylamide) (PNIPAM) as building blocks are reported in this paper. The inner architecture structure and size of complex micelles formed by H-shaped self-assemblies were effectively adjusted when the solution temperature was increased above the lower critical solution temperature of PNIPAM segments. Furthermore, it was found that the architecture of self-assemblies underwent a transition from the complex micelles based on primary micelles with hybrid PEG/PNIPAM shells to large complex micelles based on primary micelles with hybrid PTHF/PNIPAM cores and PEG shells during the thermal-induced self-assembly process. The adjustable release rate of doxorubicin (DOX) from the DOX-loaded complex micelles and basic cell experiments further proved the feasibility of these self-assemblies as the thermal-responsive drug delivery system. [ABSTRACT FROM AUTHOR]

A novel smart catalyst of Au nanoparticles supported on EDTA (ethylenediaminetetraacetic acid) functionalized temperature-sensitive copolymer consists of N -isopropyl acrylamide (NIPAM) and allylamine onto silica-modified Fe 3 O 4 MNP (Fe 3 O 4 @Si@P(NIPAM- co -allylamine)-EDTA@Au) was prepared. Initially, Fe 3 O 4 was synthesized and modified with silica particles, and then P(NIPAM- co -allylamine) was grafted onto it via conventional free radical polymerization. Afterwards, polymer grafted MNPs were functionalized with EDTA and decorated with Au NPs to produce an organized heterogenous catalytic structure. Easy separation and recycling, high dispersion of catalytic sites, as well as good thermal stability, and superior efficiency in water as a green solvent are among the great advantages of this system. The novel heterogeneous catalyst showed remarkable catalytic activity for the reduction of numerous aryl-nitro derivatives containing electron-poor, electron-rich, and ortho-substituted. This catalytic system performed excellently for at least 8 repeated cycles without significant degradation in catalytic activity, structure change, and leaching. Furthermore, the temperature responsiveness feature of the catalyst causes the catalyst's switchable on/off behavior. [Display omitted] • AuNPs supported on modified thermo-responsive polymer grafted Fe 3 O 4. • The catalyst applied for reduction of nitroarenes. • Easy separation and superior efficiency in water are among the great advantages of this system. • The thermo-responsiveness feature of the catalyst causes its switchable on/off behavior. [ABSTRACT FROM AUTHOR]

In order to construct the artificial cells and to understand the physicochemical properties of living cells, it is important to clarify the cell-sized confinement effect on the behaviours of bio-inspired polymers. We report the dynamic behaviours of aqueous hydroxypropyl cellulose (HPC) solution coated with phospholipids in oil (water-in-oil droplets, W/O droplets), accompanied by an increase in the temperature. We directly observed the beginning of phase separation of HPC solution using a fluorescence microscope and confirmed the dependence of such phenomena on droplet size. The results indicate that the start time of phase separation is decreased with an increase in droplet size. The experimental results suggest that the confinement situation accelerates the phase separation of aqueous HPC solutions. [ABSTRACT FROM AUTHOR]

ε-Poly- l-lysine ( ε-PL) is a natural preservative for food processing industry. A thermo-responsive polymer, attached with Cu or Ni, was prepared for metal-chelate affinity precipitation for purification of ε-PL. The low critical solution temperatures (LCSTs) of these polymers were close to the room temperature (31.0-35.0 °C). The optimal adsorption conditions were as follows: pH 4.0, 0 mol/L NaCl, ligand density 75.00 μmol/g, and 120 min. The ligand Cu showed a stronger affinity interaction with ε-PL and the highest adsorption amount reached 251.93 mg/g polymer. The elution recovery of ε-PL could be 98.42% with 0.50 mol/L imidazole (pH = 8.0) as the eluent. The method could purify ε-PL from fermentation broth and the final product was proved as electrophoretic pure by SDS-PAGE. Moreover, these affinity polymers could be recycled after the purification of ε-PL and the recoveries were above 95.00%. [ABSTRACT FROM AUTHOR]

Naturally occurring osmolytes are small organic compounds that affect the functioning of the macromolecule and ever-present in the living systems. Trimethylamine N-oxide (TMAO), betaine and sarcosine are among the family of methylamines which are a class of osmolytes that may lead to the alteration in the transition behaviour of thermo-responsive polymers (TRPs). In this context, we have extended our work in the direction of exploring influence of various methylamines on the lower critical solution temperature (LCST) of poly (vinyl methyl ether) (PVME). Herein this study, we used various biophysical techniques to explore the impactful aspect of methylamines on the PVME polymer. The structural integrity of the additive is found to play a major role in altering the phase transition temperature of PVME. These additives are observed to have high binding affinity for water as compared to the polymer which result in the swollen to collapsed transition of PVME at the lower temperatures than the typical LCST of the polymer. One of the common aspects in all the three additives is their positive and negative charges separation that allows their effective binding with the water molecules. Although, each osmolytes decreases the LCST of the PVME, however, highest decrease is observed with sarcosine and lowest for TMAO. In case of sarcosine, less sterically hindered N atom may directs the possibility of its H-bonding ability towards water as compared to that for TMAO and betaine containing sterically hindered N atom. [ABSTRACT FROM AUTHOR]

A thermo-responsive polymer with hydrophilic to hydrophobic transition behavior, poly(vinyl caprolactam-co-hydroxyethyl acrylamide) P(VCL-co-HEAA), was prepared by copolymerization of vinyl caprolactam and N-hydroxyethyl acrylamide via free radical solution polymerization. The resulting copolymer was characterized by Fourier transform infrared spectroscopy (FTIR), 1 H nuclear magnetic resonance (NMR), gel permeation chromatography (GPC), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). The lower critical solution temperature (LCST) of P(VCL-co-HEAA) was determined at 34.5 °C. This thermo-responsive polymer was then grafted onto cotton fabrics using 1,2,3,4-butanetetracarboxylic acid (BTCA) as crosslinker and sodium hypophosphite (SHP) as catalyst. FTIR and energy dispersive X-ray spectroscopy (EDS) studies confirmed the successful grafting reaction. The modified cotton fabric exhibited thermo-responsive behavior as evidenced by water vapor permeability measurement confirming decreased permeability at elevated temperature. This is the first demonstration that a PVCL based copolymer is grafted to cotton fabrics. This study provides a new thermo-responsive polymer for fabrication of smart cotton fabrics with thermally switchable hydrophilicity. [ABSTRACT FROM AUTHOR]