- Abstract：Functional hyperbranched polymers, as an important class of materials, are widely applied in diverse areas. Therefore, the development of simple and efficient reactions to prepare hyperbranched polymers is of great significance. In this work, trialdehydes, diamines, and trimethylsilyl cyanide could easily undergo multicomponent polymerization under mild conditions, producing hyperbranched poly(α-aminonitrile)s with high molecular weights (Mw up to 48700) in good yields (up to 85%). The hyperbranched poly(α-aminonitrile)s have good solubility in commonly used organic solvents, high thermal stability as well as morphological stability. Furthermore, due to the numerous aldehyde groups in their branched chains, these hb-poly(α-aminonitrile)s can undergo one-pot, two-step, four-component post-polymerization with high efficiency. This work not only confirms the efficiency of our established catalyst-free multicomponent polymerization of aldehydes, amines and trimethylsilyl cyanide, but also provides a versatile and powerful platform for the preparation of functional hyperbranched polymeric materials.Keywords：Catalyst-free;multicomponent polymerization;Hyperbranched polymer;Post-polymerization4|0|0
Updated：2025-01-08 -
Multi-Cyclic Swelling for Self-Regulated Growth of Covalently Crosslinked Polymers Enhanced Publication
Abstract：Organisms are capable of self-growth through the integration of the nutrients provided by the external environment. This process slows down when they grow. In this study, we mimicked this self-regulated growth via a simple swelling-polymerization strategy in which the stretching polymer chains in the original networks provide entropic elasticity to restrict growth in high growth cycles. Using typical covalently crosslinked polymers, such as acrylamide-based hydrogels and HBA-based elastomers, as examples, we demonstrate that the crosslinked polymers can absorb polymerizable compounds through a swelling-polymerization process to expand their sizes, but the growth extent becomes smaller with increasing growth cycle until reaching a plateau. In addition to their size, these materials become stiffer and exhibit less swelling ability in solvents. Our work not only provides a new growing mode to tune the properties of crosslinked polymers but also discloses the underlying mechanism of crosslinked polymers in multi-cyclic swelling conditions.Keywords：Crosslinked Polymers;Swelling;Self-growing;Mechanical property100|37|0Updated：2024-12-06 - Abstract：Due to the rapid development and potential applications of iron(III)-alginate (Fe-Alg) microgels in biomedical as well as environmental engineering, this study explores the preparation and characterization of spherical Fe-Alg microgels using droplet microfluidics combined with an external ionic crosslinking method. This study focused on the role of Fe3+ and examined its effects on the physical/chemical properties of microgels under different ionic conditions and reduced or oxidized states. The pH-dependent release behavior of Fe3+ from these microgels demonstrates their potential biomedical and environmental applications. Furthermore, the microgels can exhibit magnetism simply by utilizing in situ oxidation, which can be further used for targeted drug delivery and magnetic separation technologies.Keywords：Fe-alginate microgels;Droplet microfluidics;In situ oxidation;Magnetism55|54|0Updated：2024-12-06
- Abstract：Polymer fibers are an important class of materials throughout human history, evolving from natural fibers such as cotton and silk to modern synthetic fibers such as nylon and polyester. With the advancement of materials science, the development of new fibers is also advancing. Polymer fibers based on dynamic covalent chemistry have attracted widespread attention due to their unique reversibility and responsiveness. Dynamic covalent chemistry has shown great potential in improving the spinnability of materials, achieving green preparation of fibers, and introducing self-healing, recyclability, and intelligent response properties into fibers. In this review, we divide these fiber materials based on dynamic covalent chemistry into monocomponent fibers, composite fibers, and fiber membranes. The preparation methods, structural characteristics, functional properties, and application performance of these fibers are summarized. The application potential and challenges of fibers based on dynamic covalent chemistry are discussed, and their future development trends are prospected.Keywords：Dynamic covalent chemistry;Monocomponent fibers;Composite fibers;Fiber membranes43|90|0Updated：2024-11-25
- Abstract：It is urgent to develop high-performance polyimide (PI) films that simultaneously exhibit high transparency, exceptional thermal stability, mechanical robustness, and low dielectric to fulfil the requirements of flexible display technologies. Herein, a series of fluorinated polyimide films (FPIs) were fabricated by the condensation of 5,5′-(perfluoropropane-2,2-diyl) bis(isobenzofuran-1,3-dione) (6FDA) and the fluorinated triphenylmethane diamine monomer (EDA, MEDA and DMEDA) with heat-crosslinkable tetrafluorostyrene side groups, which was incorporated by different numbers of methyl groups pendant in the ortho position of amino groups. Subsequently, the FPI films underwent heating to produce crosslinking FPIs (C-FPIs) through the self-crosslinking of double bonds in the tetrafluorostyrene. The transparency, solvent resistance, thermal stability, mechanical robustness and dielectric properties of FPI and C-FPI films can be tuned by the number of methyl groups and crosslinking, which were deeply investigated by virtue of molecular dynamics (MD) simulations and density functional theory (DFT). As a result, all the films exhibited exceptional optically colorless and transparent, with transmittance in the visible region of 450−700 nm exceeding 79.9%, and the cut-off wavelengths (λoff) were nearly 350 nm. The thermal decomposition temperatures at 5% weight loss (Td5%) for all samples exceeded 504 °C. These films exhibited a wide range of tunable tensile strength (46.5–75.1 MPa). Significantly, they showed exceptional dielectric properties with the dielectric constant of 2.3–2.5 at full frequency (107–20 Hz). This study not only highlights the relationship between the polymer molecular structure and properties, but offer insights for balancing optical transparency, heat resistance and low dielectric constant in PI films.Keywords：Crosslinkable fluorinated polyimide;Methyl group;Triphenylmethane;Transparency;Thermal stability;Low dielectric constant36|62|0Updated：2024-11-25
- Abstract：Stimuli-responsive shape-changing materials, particularly hydrogel and liquid crystal elastomer (LCE), have demonstrated significant potential for applications across various fields. Although intricate deformation and actuation behaviors have been obtained in either hydrogels or LCEs, they typically undergo reversible shape change only once (e.g., one expansion plus one contraction) during one heating/cooling cycle. Herein, we report a study of a novel liquid crystalline hydrogel (LCH) and the achievement of dual actuation in a single heating/cooling cycle by integrating the characteristics of thermoresponsive hydrogel and LCE. The dual actuation behavior arises from the reversible volume phase transition of poly(N-isopropylacrylamide) (PNIPAM) and the reversible order-disorder phase transition of LC mesogens in the LCH. Due to a temperature window separating the two transitions belonging to PNIPAM and LCE, LCH actuator can sequentially execute their respective actuation, thus deforming reversibly twice, during a heating/cooling cycle. The relative actuation degree of the two mechanisms is influenced by the mass ratio of PNIPAM to LCE in the LCH. Moreover, the initial shape of a bilayer actuator made with an active LCH layer and a passive polymer layer can be altered through hydration or dehydration of PNIPAM, which further modifies the dual actuation induced deformation. This work provides an example that shows the interest of developing LCH actuators.Keywords：Liquid crystalline hydrogel;Dual actuation;Thermoresponsive hydrogel;Liquid crystal elastomer19|22|0Updated：2024-11-25
- Abstract：Insulin is an essential and versatile protein taking part in the control of blood glucose levels and protein anabolism. However, under prolonged storage or high temperature stress, insulin tends to unfold and aggregate into toxic amyloid fibrils, leading to loss of physiological function. Inspired by natural chaperones, a series of temperature-sensitive polycaprolactone-based micelles were designed to prevent insulin from deactivation. The micelles were fabricated through the self-assembly of amphiphilic copolymers of methoxy poly(ethylene glycol)-poly(4-diethylformamide caprolactone-co-caprolactone) (mPEG17-P(DECL-co-CL)), which had a regular spherical morphology with particle sizes of about 100 nm. In addition, the lower critical solution temperature (LCST) of the micelles could be tuned to 9 and 29 °C by changing the ratio of DECL to CL. Benefiting from the temperature-sensitivity of DECL segment, the binding ability of micelles to insulin could be modulated by changing the temperature. Above LCST, micelles effectively inhibited insulin aggregation and protected it from thermal inactivation due to the strong binding ability between the hydrophobic segment DECL and insulin. Below LCST, DECL segment returned to hydrophilic and bound weakly with insulin, leading to the release of insulin and assisting in its recovery of secondary structure. Thus, these temperature-sensitive micelles provided an effective strategy for insulin protection.Keywords：Temperature-sensitive;Insulin;Micelles;Chaperones12|17|0Updated：2024-11-25
- Abstract：Polymer adsorption at solid interfaces plays an important role in the dynamics of nanoscale polymer films. We investigated the influence of the interfacial chain adsorption on the glass transition temperature (Tg) and dewetting of polystyrene (PS) thin films on a graphene substrate that has strong interaction with PS. We found that the Tgs of PS films show a non-monotonic trend with increasing amount of polymer adsorption at the interface—first increasing and then decreasing, and this change in Tg is accompanied by a wetting-dewetting transition of the PS films. Film morphological analysis showed that the PS films dewet from the interfacially adsorbed layers rather than from the substrate, i.e., autophobic dewetting, indicating the presence of an unfavorable interaction between the adsorbed and free PS chains. We ascribed the repulsive interaction to the formation of a dense adsorbed layer on graphene due to the π-π interaction between PS and graphene, which prevents the non-adsorbed PS chain from penetrating into the adsorbed layer. This may lead to drops in Tg at high adsorption extent.Keywords：Polymer adsorption;Interfacial dynamics;Graphene;Autophobic dewetting;Thin films43|72|0Updated：2024-11-14
- Abstract：Fibers with deformation-triggered responses are essential for smart textiles and wearable electronics. Here, smart core-shell elastomer fibers with a conductive core and a liquid crystal elastomer shell showing simultaneous resistance and color responses are designed and prepared. The conductive core is consisted of interconnected liquid metal nanodroplets dispersed in a polymer matrix and the elastomer shell is made of cholesteric liquid crystals. When stretched, the fiber resistance increases as the interconnected pathways of liquid metal nanodroplets along the fiber axis become narrower, and the selective reflection color from the fiber surface blueshifts since the cholesteric pitch decreases. The smart elastomer fibers could be woven into smart textiles and respond to various mechanical deformations, including stretching, bending, compression and twisting. The average resistance change is 51% under 100% strain and its variation is smaller than 4% over 500 cycles, showing remarkable fatigue resistance. The simultaneous resistance and color responses to mechanical deformations make the fibers attractive for broad applications, such as flexible electronics.Keywords：Elastomer fiber;Core-shell;Simultaneous responses;Resistance;Color31|106|0Updated：2024-11-14
- Abstract：Chemical recycling/upcycling of plastics has emerged as one of the most promising strategies for the plastic circular economy, enabling the depolymerization and functionalization of plastics into valuable monomers and chemicals. However, studies on the depolymerization and functionalization of challenging super engineering plastics have remained in early stage and underexplored. In this review, we would like to discuss the representative accomplishments and mechanism insights on chemical protocols achieved in depolymerization of super engineering plastics, especially for poly(phenylene sulfide) (PPS), poly(aryl ether)s including poly(ether ether ketone) (PEEK), polysulfone (PSU), polyphenylsulfone (PPSU) and polyethersulfone (PES). We anticipate that this review will provide an overall perspective on the current status and future trends of this emerging field.Keywords：Super engineering plastics;Chemical recycling/upcycling;Depolymerization;Functionalization69|88|0Updated：2024-11-08
- Abstract：As a powerful synthetic tool, ruthenium-catalyzed ring-opening metathesis polymerization (ROMP) has been widely utilized to prepare diverse heteroatom-containing polymers. In this contribution, we report the synthesis of the novel imine-based polymer through the copolymerization of cyclooctene with cyclic imine comonomer via ROMP. Because of the efficient hydrolysis reactions of the imine group, the generated copolymer can be easily degraded under mild condition. Moreover, the generated degradable product was the telechelic polymer bearing amine group, which was highly challenged for its direct synthesis. And this telechelic polymer could also be used for the further synthesis of new polymer through post-transformation. The introduction of imine unit in this work provides a new example of the degradable polymer synthesis.Keywords：Degradable polymer;Ring-opening metathesis polymerization;Imine-based polymer;Copolymerization25|81|0Updated：2024-11-07
- Abstract：Achieving continuous motions typically requires dynamic external stimuli for cyclic deformation, or crafted geometries with intricate modules to form a self-regulated feedback loop upon static stimulation. It is still a grand challenge to realize self-sustained motion in soft robots subject to unchanging environment, without complex geometry or a control module. In this work, we report soft robots based on an anisotropic cylindrical hydrogel showing self-regulated, continuous rolling motions under constant light irradiation. The robots are animated by mirror-symmetry-breaking induced by photothermal strain gradient. The self-sustained motion is attributed to the fast and reversible deformation of the gel and the autonomous refresh of the irradiated region during the rolling motion. The hydrogel robots can reach a rolling speed of 1.27 mm·s−1 on a horizonal surface and even climb a ramp of 18° at a speed of 0.57 mm·s−1 in an aqueous environment. Furthermore, the hydrogel robots can overcome an obstacle, with rolling direction controllable through irradiation angle of the light and local irradiation on selective regions. This work suggests a facile strategy to develop hydrogel robots and may provide unforeseen inspirations for the design of self-regulated soft robots by using other intelligent materials.Keywords：Self-sustained motions;Light-driven;Rolling;Anisotropic hydrogels;Soft robots114|80|0Updated：2024-10-23
- Abstract：Designing the kinetic pathways of assembling macromolecules such as block copolymers and DNA strands is crucial not only for an achievement of thermodynamically equilibrium nanostructures over macroscopic areas, but also for a better understanding of formation process of higher-level superstructures where well-tailored assemblies act as mesoscopic building units. Theoretical analysis and computer simulations provide excellent opportunities to microscopically reveal the kinetics and mechanism of structural evolution as well as the collective behaviors of building units. In this perspective, we summarize our efforts of theoretical and computational modelling to understand the long-range ordering mechanisms and the organization kinetics of assembling macromolecules along designable pathways. First, we present the computational modelling and recent strategies of designable pathways for the achievement of long-range ordering. Then, from the computational views, we give the applications of pathway-designed strategies to explore the ordering mechanism and kinetics in the course of structural evolution, covering the block copolymers and their nanocomposites under zone annealing as well as the hierarchical self-assembly of mesoscopic building units (e.g., patchy micelles and DNA-functionalized nanoparticles). Finally, we outlook future directions in the field of designable pathways for the achievement of long-range ordered nanostructures. This perspective could promote further efforts towards the wide applications of theoretical and computational modelling in the construction of soft hybrid metamaterials.Keywords：Dynamic self-consistent field theory;Structural evolution;Block copolymers;Hierarchical self-assembly;Polymerization61|59|0Updated：2023-03-03
- Abstract：The integration of high mechanical toughness, impact strength as well as excellent flame-retardant properties toward epoxy resins (EPs) have always been a dilemma. The inadequate overall performance of EPs severely restricts their sustainable utilization in engineering aspects over long-term. Herein, a new bio-based agent (diglycidyl ether of magnolol phosphine oxide, referred as DGEMP) derived from magnolol (classified as lignan), extracted from natural plants Magnolia officinalis, was successfully synthesized and further employed as a flame-retardant reactive additive to diglycidyl ether of bisphenol A (DGEBA). As demonstration, the composite resin, DGEBA/15DGEMP (15 wt% DGEMP), achieved an Underwriters Laboratories-94 V-0 rating with a high limiting oxygen index (LOI) value (41.5%). In cone calorimeter tests, it showed that heat release and smoke production were effectively inhibited during combustion, wherein the peak heat release rate (PHRR) value of DGEBA/15DGEMP was reduced by 50% compared to neat DGEBA. Additionally, it exhibited a superior tensile strength (82.8 MPa), toughness (5.11 MJ/m3) and impact strength (36.5 kJ/m2), much higher than that of neat DGEBA (49.7 MPa, 2.05 MJ/m3 and 20.9 kJ/m2). Thus, it is highly anticipated that DGEMP imparts significantly improved mechanical and fire-retarded properties to conventional EPs, which holds a great potential to address the pressing challenges in EP thermosets industry.Keywords：Epoxy resin;Magnolol;Phosphine oxide;Toughness;Flame retardant240|67|1Updated：2023-02-21
- Abstract：Dissipative particle dynamics (DPD) with bond uncrossability shows a great potential in studying entangled polymers, however relatively little is known of applicability range of entangled DPD model to be use as a model for ideal chains and properly describe the full dynamics of entangled melts. Therefore, we perform a comprehensive study on structure, dynamics and linear viscoelasticity of a typical DPD entangled model system, semiflexible linear polymer melt. These polymers obey Flory’s ideality hypothesis in chain dimensions, but their local structure exhibits nonideal behavior due to weak correlated hole effect. Both monomer motion and viscoelasticity relaxation reproduce the full pictures as predicted by reptation theory. The stronger chain length dependent diffusion coefficient and relaxation time as well as dynamic moduli are in close agreement with predictions of modern tube model that accounts for additional relaxation mechanisms besides chain reptation. However, an anomalous sub-diffusive center of mass motion is observed both before and after the intermediate reptation regime and the cross-correlation between chains is not negligible even these polymers obey stress-optical law, indicating limitations of the reptation theory. Hence semiflexible linear entangled DPD model can correctly describe statics and dynamics of entangled polymer melts.Keywords：Entangled polymer melts;Dynamics;Linear viscoelasticity;Dissipative particle dynamics42|55|1Updated：2023-02-07
- Abstract：A deep neural network model generally consists of different modules that play essential roles in performing a task. The optimal design of a module for use in modeling a physical problem is directly related to the success of the model. In this work, the effectiveness of a number of special modules, the self-attention mechanism for recognizing the importance of molecular sequence information in a polymer, as well as the big-stride representation and conditional random field for enhancing the network ability to produce desired local configurations, is numerically studied. Network models containing these modules are trained by using the well documented data of the native structures of the HP model and assessed according to their capability in making structural predictions of unseen data. The specific network design of self-attention mechanism adopted here is modified from a similar idea in natural language recognition. The big-stride representation module introduced in this work is shown to drastically improve network's capability to model polymer segments of strong lattice position correlations.Keywords：Deep neural network;Self-attention mechanism;Big-stride representation;Conditional random methods8|33|0Updated：2023-01-31
- Abstract：Entropic elasticity of single chains underlies many fundamental aspects of mechanical properties of polymers, such as high elasticity of polymer networks and viscoelasticity of polymer liquids. On the other hand, single chain elasticity is further rooted in chain connectivity. Recently, mechanically interlocked polymers, including polycatenanes and polyrotaxanes, which are formed by connecting their building blocks (cyclic and linear chains) through topological bonds (e.g., entanglements), emerge as a conceptually new kind of polymers. In this work, we employ computer simulations to study linear elasticity of single linear polycatenane (or [n]catenane), in which n rings are interlocked through catenation into a chain of linear architecture. Aim of this work is to illuminate the specific role of catenation topology in the elastic moduli of linear polycatenanes by comparing with those of their [n]bonded-ring counterparts, which are formed by connecting the same number of rings but via covalent bonds. Simulation results lead to a conclusion that topological catenation makes [n]catenanes exhibit larger elastic moduli than their linear and [n]bonded-ring counterparts,i.e., larger elastic moduli in the case of [n]catenanes. Furthermore, it is revealed that those [n]catenanes composed of a smaller number of rings (smaller n) possesses larger elastic moduli than others of the same total chain lengths. Molecular mechanisms of these findings are discussed based on conformational entropy due to topological constraints.Keywords：Single chain elasticity;Polycatenane;Computer simulation25|45|0Updated：2023-01-31
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