The thermoresponsive behaviour of cross-linked poly(
N
-isopropylacrylamide) (pNIPAm) nanogels makes these materials particularly attractive for a variety of applications. Literature data report the ...use of different methodologies for preparing nanogels, which can be divided into heterogeneous and homogeneous polymerisation approaches. Heterogeneous polymerisation occurs above the volume phase transition temperature (VPTT) of pNIPAm due to water expulsion from the network of the forming polymer. On the contrary, homogeneous polymerisation is conducted below the VPTT, so that the nanogel is in the swollen state during the polymerisation process. Here, we study the effect of phase separation during polymerisation, which reveals a significant influence on the particle size and internal structure, as well as on the thermoresponsive and interfacial behaviour of pNIPAm nanomaterials. We propose that heterogeneous polymerisation leads to preferential localisation of hydrophilic initiator residues on the particle surface, while during homogeneous polymerisation, the initiator groups are distributed within the nanogel network. These results highlight the importance of the choice of polymerisation temperature as well as initiator for the synthesis of pNIPAm gels, as this significantly affects their characteristics and application.
The choice of the polymerisation temperature and initiator in the synthesis of poly(
N
-isopropylacrylamide)-based nanogels can significantly influence their structure, morphology and thermoresponsive properties.
Developing the elastomer materials with high mechanical robustness through simple and environmentally friendly methods poses significant challenges. In this research, a simple solvent‐free ...polymerization method is reported to synthesize a transparent polyurea‐urethane elastomer using polycaprolactone (PCL) as soft segment and adjusting various hard segments. The target elastomer successfully combine acceptable mechanical performance and exceptional crack tolerance, whereby the notched samples can readily lift 25000 times (a rarely reported value) its weight. Moreover, the superhigh elastic restorability allow target elastomer recover to its original dimension from elongation over 5 times or to fracture. These results are attained due to the presence of densely and uniformly distributed hard microdomains within the elastomer, leading to effective energy dissipation. Furthermore, owing to the linear structure of the molecular chains and the reversible hydrogen‐bonding interactions between the chains, target elastomer can be conveniently healed and recycled under heating conditions. This research can provide a general and feasible strategy for the construction of elastomer materials with exceptional comprehensive properties, and the elastomers are expected to be applied in emerging fields such as protective elements and flexible electronics.
As shown, IPDI‐PCL‐DMTDA was obtained through an extremely simple and controllable solvent‐free polymerization method. The outstanding comprehensive performance of the target elastomer was mainly attributed to the unique hard domain structure formed by multiple hydrogen bonds in its polymer network, while its mechanical properties were at the forefront among the elastomers reported in the literature.
•A B15C5-based lithium ion-imprinted polymer was synthesized and characterized.•The adsorption equilibrium was reached within 30 min in a 300 mg•L-1 solution at pH = 8.5.•The maximum equilibrium ...adsorption capacity was 30.53 mg·g−1, with an imprinting factor of 1.71.•The prepared Li-IIP shows good selectivity, stability and reusability.
With the rapid development of electric vehicles and new energy industries, there has been a significant increase in demand for lithium resources. This study presents a novel approach using a lithium ion-imprinted polymer (Li-IIP) prepared through bulk polymerization, which can effectively adsorb lithium ions from salt lake brines. The Li-IIP was synthesized using Li+ as the template ion, methacrylic acid (MAA) as the functional monomer, and methanol/acetonitrile as the solvent. Crosslinking of the polymerization reaction was achieved with ethylene glycol dimethacrylate (EGDMA), initiated by azobisisobutyronitrile (AIBN). Additionally, benzo-15-crown-5 (B15C5) was introduced as a selective ligand to enhance immobilization of the template ion. Characterization techniques including Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), BET nitrogen adsorption analysis, thermogravimetric analysis (TG), and zeta potentiometry were employed to analyze Li-IIP properties. The effects of preparation conditions on Li-IIP synthesis and adsorption conditions on its capacity were investigated. Results showed that after 30 min of adsorption in a 300 mg·L-1 solution at pH = 8.5, the equilibrium adsorption capacities of imprinted material (IIP) and non-imprinted material (NIP) were found to be 30.53 mg·g−1 and 17.81 mg·g−1 respectively, resulting in an imprinting factor of 1.71. Moreover, Li-IIP displayed good selectivity towards Li+ in the presence of Na+, K+, Ca2+, and Mg2+, exhibiting an adsorption capacity retention rate of 89.20 % even after eight adsorption–desorption cycles. Therefore, the synthesized Li-IIP demonstrates good selective adsorption capacity for Li+, and provides a new approach for lithium extraction through adsorption from salt lake brines.
In the present work, the in situ incorporation of curcumin was carried out in a polymer matrix through bulk polymerization to improve its photostability. It was found that extraction of curcumin from ...turmeric extract by the precursor monomer methyl methacrylate (MMA) can be performed immediately before the polymerization in order to reduce the degradation of the fluorescent species by the initiator system, although the obtained results also showed that incorporation of the turmeric extract into monomer can retard the polymerization kinetics. Despite that, the fluorescence properties of curcumin were preserved after incorporation in a solid polymeric matrix, which also enhanced the fluorophore photostability, avoiding the rapid degradation of the fluorophore observed when it is dispersed in solvents. Furthermore, it was also observed that addition of acrylic acid (AA) as a comonomer enhanced the photochemical stability of the turmeric extract incorporated into the polymer matrix and promoted the bathochromic effect, when compared to the spectroscopic behavior of the extract obtained from MMA, both in solution and solid state. It was possible to optimize the synthesis condition with help of a standard factorial experimental design, allowing the simultaneous attainment of high monomer conversion and fluorescence properties of the obtained material.
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•Fluorescent polymers are versatile materials due to their accumulating properties.•The photochemical stability of curcumin is higher when incorporated into a polymer matrix.•Fluorescent polymers can be used as biomarkers in biomedical applications.
The fabrication of crystalline 2D conjugated polymers with well-defined repeating units and in-built porosity presents a significant challenge to synthetic chemists. Yet they present an appealing ...target because of their desirable physical and electronic properties. Here we report the preparation of a 2D conjugated aromatic polymer synthesized via C-C coupling reactions between tetrabromopolyaromatic monomers. Pre-arranged monomers in the bulk crystal undergo C-C coupling driven by endogenous solid-state polymerization to produce a crystalline polymer, which can be mechanically exfoliated into micrometre-sized lamellar sheets with a thickness of 1 nm. Isothermal gas-sorption measurements of the bulk material reveal a dominant pore size of ~0.6 nm, which indicates uniform open channels from the eclipsed stacking of the sheets. When employed as an organic anode in an ambient-temperature sodium cell, the material allows a fast charge/discharge of sodium ions, with impressive reversible capacity, rate capability and stability metrics.
Degradation of the kinetically trapped bulk heterojunction film morphology in organic solar cells (OSCs) remains a grand challenge for their practical application. Herein, we demonstrate highly ...thermally stable OSCs using multicomponent photoactive layer synthesized via a facile one-pot polymerization, which show the advantages of low synthetic cost and simplified device fabrication. The OSCs based on multicomponent photoactive layer deliver a high power conversion efficiency of 11.8% and exhibit excellent device stability for over 1000 h (>80% of their initial efficiency retention), realizing a balance between device efficiency and operational lifetime for OSCs. In-depth opto-electrical and morphological properties characterizations revealed that the dominant PM6-b-L15 block polymers with backbone entanglement and the small fraction of PM6 and L15 polymers synergistically contribute to the frozen fine-tuned film morphology and maintain well-balanced charge transport under long-time operation. These findings pave the way towards the development of low-cost and long-term stable OSCs.
In the present review, we focused on the fundamental concepts of hydrogels—classification, the polymers involved, synthesis methods, types of hydrogels, properties, and applications of the hydrogel. ...Hydrogels can be synthesized from natural polymers, synthetic polymers, polymerizable synthetic monomers, and a combination of natural and synthetic polymers. Synthesis of hydrogels involves physical, chemical, and hybrid bonding. The bonding is formed via different routes, such as solution casting, solution mixing, bulk polymerization, free radical mechanism, radiation method, and interpenetrating network formation. The synthesized hydrogels have significant properties, such as mechanical strength, biocompatibility, biodegradability, swellability, and stimuli sensitivity. These properties are substantial for electrochemical and biomedical applications. Furthermore, this review emphasizes flexible and self-healable hydrogels as electrolytes for energy storage and energy conversion applications. Insufficient adhesiveness (less interfacial interaction) between electrodes and electrolytes and mechanical strength pose serious challenges, such as delamination of the supercapacitors, batteries, and solar cells. Owing to smart and aqueous hydrogels, robust mechanical strength, adhesiveness, stretchability, strain sensitivity, and self-healability are the critical factors that can identify the reliability and robustness of the energy storage and conversion devices. These devices are highly efficient and convenient for smart, light-weight, foldable electronics and modern pollution-free transportation in the current decade.
This article reviews the current state of the art with respect to RAFT alcoholic dispersion polymerization processes that proceed with polymerization-induced self-assembly (PISA) and covers the bulk ...of the literature up to mid-2016. The article is arranged according to suitable comonomers that may employed in such copolymerizations. Where appropriate we have highlighted unusual nanoparticle morphologies that are accessible, and formulation specific, as well as interesting properties associated with certain final nano-objects.
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•RAFT dispersion polymerization with polymerization-induced self-assembly (PISA) proceeds in a range of alcoholic solvents.•Nanoparticles of ‘common’ and complex morphology are readily accessible.•Nano-objects responsive to changes in temperature and/or pH can be prepared.•Reversible order-order and order-disorder transitions have been observed.
The poor electronic and ionic conductivities of covalent organic frameworks (COFs) severely restrict the development of COF‐based electrodes for practical rechargeable batteries, therefore inspiring ...more research interest from the direction of both material synthesis and technology. Herein, a dual‐porous COF, USTB‐6, with good crystallinity and rich redox‐active sites is conceived and fabricated by the polymerization of 2,3,8,9,14,15‐hexa(4‐formylphenyl)diquinoxalino 2,3‐a:2′,3′‐cphenazine and 2,7‐diaminopyrene‐4,5,9,10‐tetraone. In particular, the heterogeneous polymerization of the same starting materials in the presence of graphene affords uniformly dispersed COF nanosheets with a thickness of 8.3 nm on a conductive carbon substrate, effectively enhancing the electronic conductivity of the COF‐based electrode. Such a graphene‐supported USTB‐6 nanosheets cathode when used in a lithium‐ion battery exhibits a specific capacity of 285 mA h g−1 at a current density of 0.2 C and excellent rate performance with a prominent capacity of 188 mA h g−1 at 10 C. More importantly, a capacity of 170 mA h g−1 is retained by using the USTB‐6 nanosheets cathode after 6000 cycles charge and discharge measurement at 5 C.
A sophisticated covalent organic framework (COF) predesign and synthetic strategy, with the assistance of materials processing technology, results in a new COF‐based high‐performance organic cathode for practical lithium‐ion batteries, with a specific capacity of 285 mA h g−1 at current density of 0.2 C, and retained capacity of 170 mA h g−1 after 6000 cycles at 5 C.
Graphitic carbon nitride (g-C3N4) is a promising metal-free photocatalyst for artificial photosynthesis and renewable solar-to-fuel conversion. However, the bulk g-C3N4 (GCN-B) powders derived from ...thermal polymerization only exhibit low photocatalytic efficiency. To this end, herein, we developed a precursor-reforming protocol to prepare the unique curly architectured g-C3N4 (GCN-CLA) by the direct calcination of the formed melamine-based precursor from a nitric acid-induced hydrothermal approach. Compared to the GCN-B, the GCN-CLA having thin-layer nanosheets with an average thickness of 10 nm possesses faster photogenerated electron–hole transport, larger specific surface area, fewer defect density, and stronger hydrogen proton thermodynamic driving force. Eventually, the GCN-CLA shows a superior photocatalytic H2 improved rate of 1949 μmol g−1 h−1 under visible light, as well as a notable apparent quantum yield of 10.8% at 420 nm. Simultaneously, the photocatalytic activity of the as-fabricated GCN-CLA photocatalyst is not only much higher than that of the top-down acid treated g-C3N4 (GCN-AT) but also displays excellent photostability. Our work provides a new bottom-up precursor-reforming strategy for designing high performance g-C3N4 nanomaterials towards sustainable photocataysis applications.
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