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An ionic liquid is used as a new nitrogen and boron source to synthesize nitrogen–boron co-doped carbon-coated Na3V2(PO4)2F3 (NVPF-CNB).

Ionic liquid (IL)-decorated copolymers based on poly((ethylene glycol) methyl ether methacrylate)-co-(acrylic acid)-co-(1-vinyl-3-ethylimidazolium hexafluorophosphate) were prepared and used as bin...

Current olivine structure LiFePO4 possesses poor conductivity, which makes it unsuitable for unparalleled battery applications. This issue can be solved by improved design concepts of binder systems. Herein, an original waterborne binder polymer with efficient functional groups is designed and fabricated for LiFePO4 cathodes of lithium-ion batteries (LIBs). Compared to universal lithiated ionomer binders, the introduction of the zwitterionic structure of the ionomer enhances the ionic conductivity by nearly 100-fold. LiFePO4 cathodes assembled with limited 1.5 wt% lithiated zwitterionic ionomer (LZI) maintain markedly stable cycling performances with 95.62% retention at 1C after 250 cycles. Also, LZI-cathodes preserve good integrity structures after cycling, as confirmed by morphology analysis. In sum, LZI-cathodes look promising for potential applications in LIBs due to their numerous advantageous characteristics.

In this study, a liquid crystalline polyurethane that exhibits thermal- and light-responsive programmable shape-memory behavior was prepared via the quaternization reaction between a mesogenic azobenzene compound and a conventional polyurethane (PU). In the film, the variation in the configuration of mesogenic azobenzene units afforded the internal stress to actuate the motion of the polymer chains and induced the chains to adopt a coiled conformation, leading to the macroscopic deformation of the film under light stimulation. The hard segments of PU provided the skeleton that froze the conformation of the polymer chains and ensured that the temporary shape was maintained after removing the stimuli. The variation of the tensile stress required for maintaining the elongation of the film under different stimuli was measured, and a possible mechanism for the multiple stimuli-responsive shape deformation of the material from the point of view of the evolution of polymer chain conformations was also discussed. Moreover, flexible photomechanical devices based on the liquid crystalline polyurethane film were fabricated, and the soft devices could catch an object even in the absence of stimuli. This work can provide a creative route for the fabrication and practical application of novel photomechanical devices and soft robotics more in line with the requirements of energy-saving and intelligence.

In this study, liquid crystalline polyurethane was prepared by quaternization between ordinary polyurethane and mesogenic monomers. Meanwhile, a fast light-responsive actuator film with self-healing performance based on liquid crystalline polyurethane was successfully fabricated. In the film, the mesogenic units of the nematic compound were grafted on the polyurethane main chain, leading to liquid crystal phase of the polymer. The photoresponsive units of the liquid crystalline azobenzene were utilized as photosensitive components, and polyurethane was employed as the polymer matrix to endow the material with good film-forming and mechanical properties. The as-obtained actuator film not only showed a quick response and large shape deformation upon UV-irradiation but also exhibited temperature-induced self-healing performance. Moreover, the as-prepared light-responsive actuator film exhibited excellent properties coupled with easy fabrication, low cost, and good film-forming and relevant mechanical properties, showing promise for future practical applications in photo-driven and optomechanical devices.

Polyanion-type Na3V2(PO4)2F3 (NVPF) represents a new potential cathode material due to its sodium super ionic conductor (NASICON) structure. However, unmodified Na3V2(PO4)2F3 is restricted by its intrinsic properties, and its limitation of poor conductivity make it an unsatisfactory cathode material. Herein, a zwitterionic polymer is used as a new nitrogen and sulfur source to successfully synthesize nitrogen and sulfur co-doped carbon-coated Na3V2(PO4)2F3 (NVPF-NSC) through a sol–gel method combined with freeze-drying technology. The obtained three-dimensional framework both alleviates agglomeration between particles and improves the electrical conductivity and electrochemical performance of the material. Based on these advantages, NVPF-NSC-2 (the zwitterionic polymer was added at 25% of NVPF mass) exhibits a high specific discharge capacity (109 mA h g−1 at 0.5 C) and excellent cycle performance (with a capacity retention ratio of 92.1% after 500 cycles at 5 C and a capacity retention ratio of 87.6% after 500 cycles at 10 C with a retained capacity of 83 mA h g−1). Ex situ X-ray diffraction (ex-XRD) tests were performed to explore the charge/discharge deintercalation mechanism of Na+, with the results demonstrating the excellent cycle stability of the material. The results reported herein demonstrate that using zwitterionic polymers as a new heteroatom source is feasible and effective, providing a new idea for the future large-scale application of sodium ion batteries.

A crystalline iceplant-like nano-NaVPO4F@graphene composite is successfully synthesized by a freeze-drying process. Graphene forms a lamellar structure wherein NaVPO4F nanoparticles are uniformly adhered to the surface of graphene. The composite displays an intercalation-type reaction mechanism and excellent cycling and rate performance.

Carbon-coated VBO3 on graphene sheets (VBO3/C@G) composite synthesized by freeze-drying method is presented as anode material for lithium-ion batteries. In the final material, VBO3 nanoparticles, which are uniformly coated by amorphous carbon, are either adhered to the surface of graphene sheets or covered by graphene sheets. The amorphous carbon and graphene not only prevent the growth of VBO3 nanoparticles but also provide an excellent conductive 3D network, which is beneficial for the battery performance. The material delivers an initial charge capacity of 787 mAh g−1 at 0.1 C and maintains 697 mAh g−1 after 100 cycles at 0.1 C. It also exhibits an excellent rate performance with a charge capacity of 609 mAh g−1 at 10 C.

VBO3 nanoparticles on graphene sheets (VBO3@G) composite is synthesized by a freeze-drying method as anode material for lithium-ion batteries. After optimization of sintering temperature, reduced graphene oxide (rGO) forms a 3D-framework and VBO3 nanoparticles are adhered to the surface of rGO uniformly. The graphene sheets not only assist the formation of nanoparticles, but also provide an excellent conductive 3D network. It is found that the composite shows a good cycling performance with an initial charge capacity of 779 mAh g−1 at 0.1 C and maintains 610 mAh g−1 after 100 cycles. It also exhibits an excellent rate performance with charge capacities of 592 mAh g−1 at 5 C and 442 mAh g−1 at 10 C.

In this paper, a simple one-step doping spray method using liquid polyacrylonitrile (LPAN) is reported, for the preparation of LiNi0.8Co0.15Al0.05O2 (NCA) precursor, after calcination, to obtain a loose and porous sphere-shaped NCA (LPAN@NCA). The initial discharge specific capacity was found to be 227.9 mA h g−1 at 0.1C, which is 26.6% higher than that of the pristine sample. Its capacity retention rate was found to be 93.59% after 200 cycles, and the surface morphology of the material grains after the cycles remains intact. X-ray diffraction (XRD) analysis reveals that doping with LPAN can effectively decrease the amount of disorder of Ni2+ in Li + position that gets reduced by 2.72%. The X-ray photoelectron spectroscopy (XPS) analysis shows that after the carbonization of LPAN, the C atoms replace part of O atoms, effectively forming a new compound. The decrease in the impedance of the battery materials before and after the cycle and the increase of lithium ion mobility also confirms the effectiveness of LPAN doping. The LPAN@NCA prepared by in-situ doping of LPAN by spraying method is simple and effective, which exhibits high specific capacities, superior rate performance and excellent recycling stability, that has a good commercial application prospect.

A facile and simple electrospinning method was adopted to prepare a 3D network of Na3V2(PO4)3/C flexible fiber membrane as self-standing cathodes for sodium ion batteries. The physical and electrochemical performances are investigated by X-ray diffraction, scanning electron microscopy, transmission electron microscopy and electrochemical tests. The Na3V2(PO4)3/C nanorods displayed an excellent sodium storage performance. For example, it showed an initial capacity of 107 mA h g−1 at a current density of 0.1 C and retained almost 100% of the initial capacity at the 100th cycle. Moreover, the discharge capacity was up to 30 mA h g−1 at 30 C, suggesting a high rate capability.

There have been great developments in shape memory polymers in recent years. However, the permanent shape was usually predetermined and could not be changed during the shape memory process. This work reports a facile method for permanent shape reconfiguration of shape memory polymers using a water-soaking treatment. The impact of water molecules on the structure, morphology, and properties of zwitterionic polyurethanes (ZPUs) was carefully investigated. FT-IR, DSC, TGA, and DMA analysis revealed that polymer chains of ZPU can be easily activated by absorbing water molecules and was solidified again by removal of water molecules. Direct water-soaking treatment can eliminate previous shape recovery capability and then be used to reconfigure a new permanent shape for a new thermally induced shape memory process. Thus, this work provides an alternative approach for manufacturing complicated devices at room temperature and for easily regulating the thermally induced shape memory effect.

Shape-memory polymers with supramolecular switch have received increasing attention. This study reports the synthesis and characterization of supramolecular shape-memory polyurethane based on Cu(II)–pyridine coordination, obtained by mixing pyridine containing polyurethane with CuCl2. The results show that there are strong metal–ligand coordination interactions formed between Cu(II) and the pyridine ring in a series of CuCl2-doped polyurethane samples. The Cu(II)–pyridine coordination plays a crucial role in the enhanced physical netpoints for outstanding shape-memory properties. Indeed, the so-synthesized CuCl2-doped polyurethane exhibits not only a rapid tensile shape recovery but also excellent crimp shape recovery. The CuCl2-doped polyurethane containing suitable metal–ligand coordination interactions shows more than 99% shape fixation and more than 95% shape recovery. Our findings promote further applications of shape-memory polymers in multiple engineering fields.

In this study, a new type of a brush polyurethane containing long carbon side chains is prepared using hexamethylene diisocyanate (HDI), tetraethylene glycol (TEG), and a quaternized dihydroxyl glycol, which is previously synthesized from N-methyldiethanolamine (MDEA) and brominated alkanes. Results revealed that the brush-like polyurethane exhibits a good shape memory performance, with a shape recovery of 85%. The quaternization of long-chain alkanes onto tertiary ammonium nitrogen renders good self-healing properties to the brush polyurethane. Therefore, these thermal-induced self-healing properties are expected to make shape memory polyurethanes a good potential candidate for applications in smart coatings, smart surfaces, and other smart materials.

The advances in flexible electronics, soft robotics, and many other fields resulted in increased demands for high-performance self-healing elastomers (SHEs). In this work, novel SHEs were prepared by photo-initiated copolymerization of acrylic acid and alkyl acrylates. The as-obtained SHEs exhibited 100% autonomous self-healing efficiency at ambient temperature due to the formation of hydrogen bonding between the hydroxyl groups of acrylic acid unit and carbonyl groups of alkyl acrylate unit. The strong supramolecular interaction yielded SHEs with 3D printing capability, high stretchability, and remarkable adhesion properties. Meanwhile, biomimetic adhesion was developed by solvent-wetting method to enable convenient adherence of SHEs on various substrates. Furthermore, the introduction of carboxylic ionic liquid led to the formation of a nonleaking and attachable ionogel by 3D printing for strain sensing applications. The as-obtained strain sensor precisely detected various gestures of human fingers, and successfully recognized sign language through a comprehensive analysis of electronic signals. In sum, the high-performance SHEs look promising for future SHE-based intelligent products thanks to their common raw feedstocks, 3D printing capability, and multi-functional characteristics.

In this study, an Epoxy/POSS-liquid crystalline azobenzene-Poly (ethylene-co-vinyl acetate) (Epoxy/POSS-Azo-EVA) composite was prepared via the thermal curing of epoxy monomers and multi-functional thiol-containing Polyhedral oligomeric silsesquioxane (POSS) in an EVA matrix. The EVA matrix afforded the composite with shape memory performance. Epoxy/POSS polymer was uniformly dispersed in the matrix to act as a rigid skeleton, leading to the improvement of the mechanical properties and shape memory performance of the composite. Liquid crystalline azobenzene as the photosensitive component provided the inner stress to render the composite film with photo-induced shape-deformation behavior under UV light. The composite film not only exhibited thermal- and light-responsive programmable shape-memory behavior stimulated by heat and light, but also was recyclable and reprocessable. Moreover, the recycled composite film was processed into different functional devices. A flexible photomechanical device based on the recycled Epoxy/POSS-Azo-EVA composite film was fabricated, and the soft device deformed into a hook-shape under UV light and hooked an object whose weight is larger than that of the device. A smart wire was also prepared via assembling a stretched recycled Epoxy/POSS-Azo-EVA composite film and a copper foil by adhesive. The wire could control the status of a circuit via changing its shape under UV light and maintain the status after the removal of light. The functional devices described in this work only needed a short time of UV irradiation during a work cycle, and the devices still held the temporary shape in the absence of UV irradiation. The recyclable and reprocessable Epoxy/POSS-Azo-EVA composite film in this work could provide a creative approach for the fabrication of novel photomechanical devices and soft robotics with energy-saving, intelligence, recyclability, and sustainability.

Shape memory polymers (SMP) and zwitterionic polymers both have great applications in biomedical fields. This works successfully combines functionalities of zwitterionic polymers and SMP, developing new kind of zwitterionic copolymers having a multi-shape memory effect (SME) and a moisture-sensitive SME. The results demonstrate that a series of zwitterionic multi-SMPs, coded as p(DMAPS-co-AA), were synthesized from DMAPS and acrylic acid (AA). A micro-phase separated structure is formed in the resulting p(DMAPS-co-AA). The strong hydrogen bonding between AA segments serves as a reversible switch, while the strong electrostatic forces among DMAPS segments serve as physical crosslinkers. Therefore, shape memory testing demonstrates that p(DMAPS-co-AA) shows not only dual-SME, but also triple-SME and quadruple-sSME. Moreover, in addition to the thermally-induced SME, p(DMAPS-co-AA) also shows moisture-sensitive SME. It is thus proposed that this zwitterionic multi-SMP could find great potential applications in smart biomedical fields.

In this contribution, shape memory polymers (SMPs) of chemically-crosslinked zwitterionic polyurethanes (CZPUs) were fabricated by crosslinking of the N,N-bis(2-hydroxyethyl) isonicotinamide (BINA)/hexamethylene diisocyanate (HDI) polyurethanes system by using pentaerythritol (PER), followed by zwitterionization with 1, 3-propanesultone (PS). As the zwitterionic units increased, it was found that the glass transition of hard phase in CZPUs remains constant while that of soft phase shifted at lower temperature, and a broad glass transition was obtained. The broad glass transition enables CZPUs to display triple, quadruple, and quintuple shape memory behaviours. Meanwhile, due to the chemically-crosslinked structure, the CZPUs exhibited an excellent shape fixation and recovery. Furthermore, the CZPU also exhibited good moisture-induced shape memory effect (SME) with a fast and high shape recovery observed below 70% RH and at 37 °C. The excellent thermally-induced multi-shape memory effect and moisture-induced shape memory effect enable CZPUs to be applied as smart materials for many applications among them the biomedical fields.

Shape memory polymers (SMPs) have received significant attention from scientists in recent years. This paper presents a simple route to design light-thermo stage-responsive SMPs. A novel series of liquid crystalline shape memory polymer composites (coded as PSMPU-Azom) exhibiting stage-responsive shape memory properties were successfully prepared by incorporating 4-(4-oxyalkyl chain carbonyl) azodibenzoic acid (Azo11) into the PCL-based SMPs (PSMPU). The effect of Azo11 on the structure, morphology, and shape memory properties was carefully investigated. The results demonstrate that the incorporated Azo11 promotes the crystallizability of PSMPU. The obtained PSMPU-Azom composites form a two-phase structure comprising the PSMPU phase and Azo11 phase, while the polyurethane matrix even shows hard–soft phase separation structure. Therefore, the PSMPU-Azom composites retain the intrinsic liquid crystalline properties of Azo11. Moreover, the PSMPU-Azom composites have stage-responsive shape memory properties and hence, demonstrate unique features such as independent UV light-responsive deformation and thermal-responsive shape recovery. These composites display a rare combination of light- and thermal-responsiveness, which not only allows instantaneous shape-deformation under UV irradiation, but can also be temporarily fixed to a particular shape on stopping the UV irradiation at room temperature. The composites have good potential applications in smart optical devices, smart electronic devices, smart sensors, and robotic fingers.

Li 4 Ti 5 O 12 particles are synthesized coated with very thin graphene-like sheets in situ using liquid-polyacrylonitrile (LPAN) as the carbon source and added utilized conductivity additives to improve the conductivity of the electrode materials. The crystalline structures of Li 4 Ti 5 O 12 with 20% LPAN and different conductivity additives composites were examined by XRD. The structure and electrochemical performance of the graphene-like sheets coated Li 4 Ti 5 O 12 , with conductivity additives added, was systematically investigated. The electrochemical performance also revealed that the graphene-like sheets significantly improved the discharge capacity and cycling stability of Li 4 Ti 5 O 12 . In particular, the coated Li 4 Ti 5 O 12 with 20 wt% LPAN and 1% acetylene black (CB) reached 166.2 mAh g −1 at 10C. The performance improvement is a result of the graphene-like nanosheet conformal coating, which creates an electrically conductive network for the electrode.

This paper reports novel antimicrobial properties and shape memory properties of zwitterionic copolymers synthesized with 3-dimethyl(methacyloyloxyethyl) ammonium propane sulfonate (DMAPS) and acrylic acid (AA). The results demonstrate that the DMAPS- co -AA copolymer successfully integrates the antimicrobial properties and shape memory properties. The zwitterionic copolymer has good antimicrobial activity with bacteriostasis mechanism. Though the minimal inhibition concentration (MIC) of DMAPS- co -AA copolymer is much higher, zwitterionic copolymer is a good candidate of environmental friendly antimicrobial agent due to its nontoxic and biocompatibility. The shape memory properties of zwitterionic copolymer further encourage them many smart biomedical applications, such as suture and drug release.

This paper reports a novel humidity-responsive self-healing material based on zwitterionic polyurethanes. The material was synthesized from N,N-bis(2-hydroxylethyl) isonicotinamide (BINA), hexamethylene diisocyanate (HDI) and 1,3-propanesultone (PS). The self-healing of its structure, its mechanical properties and shape memory properties were carefully investigated. Results demonstrate that self-healing zwitterionic polyurethanes contain pyridine type sulfobetaines and that strong electrostatic interactions are formed between zwitterions acting as physical crosslinkers. The aggregation of zwitterions strongly influences the phase transition behavior of polyurethane. Bulk polyurethane shows a phase-separated structure with an amorphous soft phase. The damaged zwitterionic polyurethane structure can self-heal several times in the presence of moisture without any additive or external energy. As the proportion of zwitterions increases, the self-healing efficiency increases. The self-healing efficiency results are higher when the relative humidity is increased. The self-healing mechanism is ascribed to the improved ionic mobility upon hydration and to electrostatic forces which occur during drying. Furthermore, pyridine based zwitterionic polyurethanes also show good self-healing of their shape memory properties. Self-healed polyurethanes show both a good shape fixity and recovery. This work paves the way to develop stimulus-responsive self-healing materials for renewable shape memory applications.

This paper provides a biomaterial derived from zwitterionic polymer for controlling macrophage phagocytosis of bacteria. A series of zwitterionic copolymers, named DMAPS-co-AA, are synthesized with 3-dimethyl (methacryloyloxyethyl) ammonium propane sulfonate (DMAPS) and acrylic acid (AA). The biocompatibility of DMAPS-co-AA copolymers can be adjusted by adjusting the DMAPS-content or pH value. As the DMAPS-content increases, the biocompatibility of zwitterionic copolymer increases. The zwitterionic copolymers with DMAPS content above 30 wt% have higher biocompatibility. Moreover, the biocompatibility also increases significantly as the pH increases from 3.4 to 7.2. By adjusting the pH above 5.8, the zwitterionic copolymer with lower DMAPS-content also shows higher biocompatibility. Importantly, after incubation with the DMAPS-co-AA copolymer solutions at different pH values, phagocytosis behavior of macrophage RAW264.7 cells can also be adjusted. The phagocytosis of bacteria is enhanced at pH = 7.2. Thus, it is proposed that zwitterionic copolymers can be used for controlling phagocytosis of bacteria.

In this study, a series of novel shape memory polyurethanes (SMPUs) containing tertiary amine groups are prepared by designing hexamethylene diisocyanate (HDI)–N-methyldiethanolamine (MDEA) as soft segments and HDI-BDO as hard segments. The structure and properties of the MDEA-based SMPUs are investigated using FT-IR, NMR, DSC, TGA, DMA, POM and AFM. The results demonstrate that the MDEA-based SMPU is composed of an amorphous soft phase and hard phase. The hard phase is amorphous below 20 wt% hard segment content (HSC), whereas the HDI-BDO segments form a semi-crystalline hard phase above 30 wt% HSC. This morphology exhibits good thermally induced SMEs with 100 % shape fixity and more than 80 % shape recovery. Moreover, the MDEA-based polyurethanes are expected to be further multifunctionalized for antibacterial activity, biocompatibility, multi-responsiveness and many other properties. This work provides a new strategy for designing multifunctional shape memory polymers with amine-containing polyurethanes.

This paper reports a new type of zwitterionic polyurethane containing pyridine type zwitterionic segments for shape memory materials. The pyridine type zwitterionic shape memory polyurethanes (SMPUs) were synthesized using polyurethane polymerization from N,N-bis(2-hydroxylethethyl)isonicotinamide (BINA), hexamethylene diisocyanate (HDI), diphenylmethane diisocyanate (MDI) and 1,4-butanediol (BDO), followed by a ring-opening reaction with 1,3-propanesultone (PS). The structure and properties of the pyridine-type zwitterionic SMPUs (PyZPUs) were investigated systematically. The results demonstrate that the PyZPUs form phase-separation structures composed of a hard phase and an amorphous soft phase with a broad glass transition. The shape memory tests show that the PyZPUs have thermal-induced dual-shape memory effects (SMEs), triple-SMEs and quadruple-SMEs and also moisture-sensitive SMEs. Comparatively, the samples with PS/BINA molar ratios of 0.6–0.8 have more than 86% shape recovery and more than 95% shape fixity with a heat stimulus. Under moisture conditions, these samples also show the quickest moisture-sensitive strain recovery, up to 86%. Moreover, the PyZPUs show good biocompatibility when the content of pyridine type zwitterionic segments is beyond 21 wt%. Thus, the PyZPUs are expected to have many promising applications in smart biomedical fields.

Nano-NaVPO4F enwrapped in reduced graphene oxide is obtained via the modified freeze-drying method. In the composite, reduced graphene oxide constitutes a 3D conductive framework, and NaVPO4F particles less than 100 nm are uniformly enwrapped in the graphene sheets. The composite exhibits not only excellent cycle stability but also extraordinary rate capability in sodium-ion batteries. The corresponding discharge capacities at 10, 20, 50, and 100 C are 113.9, 112.1, 106.9, and 86.6 mAh g−1, respectively. In particularly, it delivers an initial discharge specific capacity of 110.6 mAh g−1 while obtains 100.0 mAh g−1 with the capacity retention of 90.4% at 10 C after 3000 cycles. Such superior performance can be ascribed to the uniform nanometer-sized particles and the 3D conductive graphene framework. This work implies that graphene-modified NaVPO4F can be a promising cathode material for long-cycle and high-rate sodium-ion batteries.

Both liquid crystalline polymers and shape memory polymers are attractive to researchers. This paper describes the development of a supramolecular liquid crystalline complex exhibiting a multi-shape memory effect and liquid crystalline properties. 4-n-Octyldecyloxybenzoic acid (OOBA) is connected to a pyridine-containing polyurethane (PySMPU), forming a new PySMPU/OOBA complex. The results of this study demonstrate that the complex maintains the intrinsic crystallization and liquid-crystalline properties of OOBA and combines the shape memory effects of PySMPUs. Shape memory investigations demonstrate that the PySMPU/OOBA complexes have a good multi-shape memory effect, exhibiting triple- and quadruple-shape memory behaviours. For the triple-shape memory behaviours, the strain fixity at the first stage is lower than that at the second stage, while the strain recovery at the first stage is higher than that at the second stage. Overall, increasing the OOBA content improves the strain fixity but reduces the strain recovery due to the lubrication of the OOBA long chains. The successful combination of the liquid crystalline properties and multi-shape memory effect makes the PySMPU/OOBA complexes potentially applicable in smart optical devices, smart electronic devices and smart sensors.

This study reports a novel shape memory copolymer synthesized with 2-(dimethylamino)-ethyl-methacrylate (DMAEMA) and methyl-allyl-polyethenoxy-ether (TPEG) for potential biological applications. In the DMAEMA–TPEG copolymers, TPEG segments form a semi-crystalline phase that serves as the reversible phase, while DMAEMA segments form an amorphous phase containing physical interactive networks that serve as the hard phase. As the TPEG content increases, the crystallinity and the rate of crystallization increase, and the TPEG phase changes from dispersed small spherical crystals to a continuous crystalline phase. Additionally, good crystallinity of the TPEG phase endows the copolymers with good shape fixity, whereas the shape recovery decreases as the TPEG content decreases. DMAEMA–TPEG copolymers also exhibit the multi-shape memory effect with a good triple-shape memory effect. Finally, the investigation of the water contact angle illustrates that all DMAEMA–TPEG copolymers have good hydrophilicity. Thus, it is proposed that DMAEMA–TPEG copolymers might have great potential for biological applications.

This work aimed at elucidating the influence of zwitterionic hard segments on the structures and properties of shape memory polyurethanes (SMPUs). A series of zwitterionic SMPUs was successfully prepared with N-methyldiethanolamine (MDEA), 1,3-propanesultone (1,3-PS), 1,6-hexamethylene diisocyanate (HDI) and polyethylene glycol (PEG6000). The influence of MDEA-PS-based zwitterionic hard segment on structure, morphology, thermal property, shape memory property and cytocompatibility were systematically investigated. The results demonstrated that the PEG-based zwitterionic SMPUs (PEG-ZSMPUs) formed phase separation structure consisting of crystalline soft phase and amorphous hard phase. The MDEA-PS zwitterionic segments showed a tendency to form ionic clusters in hard segments, which served as reinforced net points. Shape memory analysis showed that zwitterionic PEG-ZSMPUs containing a high content of zwitterionic segments had thermal-induced shape memory effects. Finally, cytotoxic assays demonstrated that MDEA-PS zwitterionic segment improved the biocompatibility of PEG-ZSMPUs. The zwitterionic PEG-ZSMPUs could thus have a promising application in smart biomedical fields.

In this paper, we developed a photo-thermo staged-responsive shape-memory polymer network which has a unique ability of being spontaneously photo-responsive deformable and thermo-responsive shape recovery. This new type of shape-memory polyurethane network (A-SMPUs) was successfully synthesized with 4,4-azodibenzoic acid (Azoa), hexamethylenediisocyanate (HDI) and polycaprolactone (PCL), followed by chemical cross-linking with glycerol (Gl). The structures, morphology, and shape-memory properties of A-SMPUs have been carefully investigated. The results demonstrate that the A-SMPUs form micro-phase separation structures consisting of a semi-crystallized PCL soft phase and an Azoa amorphous hard phase that could influence the crystallinity of PCL soft phases. The chemical cross-linking provided a stable network and good thermal stability to the A-SMPUs. All A-SMPUs exhibited good triple-shape-memory properties with higher than 97% shape fixity ratio and 95% shape recovery ratio. Additionally, the A-SMPUs with higher Azoa content exhibited interesting photo-thermo two-staged responsiveness. A pre-processed film with orientated Azoa structure exhibited spontaneous curling deformation upon exposing to ultraviolet (UV) light, and curling deformation is constant even under Vis light. Finally, the curling deformation can spontaneously recover to the original shape by applying a thermal stimulus. This work demonstrates new synergistically multi-responsive SMPUs that will have many applications in smart science and technology.

In recent years, modifying cathode materials' surfaces become a popular pursuit. This paper reveals a novel spinel LiMn 2 O 4 in situ coated with graphene-like membrane prepared using liquid-polyacrylonitrile (LPAN) as the carbon source. The structure and electrochemical performance of graphene-like membrane-coated spinel LiMn 2 O 4 are investigated systematically. The membrane has a typical graphene-like layer carbon structure that can be applied the LiMn 2 O 4 particles' surfaces in situ without affecting their crystal structure. Moreover, the graphene-like membrane helps to increase the particle size. The electrochemical performance reveals that coating the graphene-like membrane in situ significantly improves the discharge capacity and cycling stability of the spinel LiMn 2 O 4 . In particular, the spinel LiMn 2 O 4 coated with a calcined 20 wt% LPAN graphene-like membrane in situ reached 131.1 mAh g −1 at room temperature, and up to 96% capacity is retained after 50 cycles at 0.1 C. The cyclic voltammetry and electrochemical impedance spectra analyses indicate that the graphene-like membrane does not influence the insertion or desertion of Li + . The improved electrochemical performance is attributed to the decreased manganese dissolution in the electrolyte and the smaller charge transfer resistance generated by the graphene-like membrane coating.

Carbon coating is an effective approach to improve the cycling stability of silicon (Si) anodes for lithium-ion batteries. In this research, we report a facile one-step carbon-thermal method to coat Si nanoparticles with nitrogen-doped (N-doped) graphene-like nanosheets derived from a liquid-polyacrylonitrile (LPAN) precursor. The coated Si anode displays an initial coulombic efficiency of 82%, which is about three times greater than its pristine counterpart, as well as superior cycling stability. The performance improvement is a result of the N-doped graphene-like nanosheet conformal coating, which not only creates an electrically conductive network for the electrode, but also provides a buffering matrix to accommodate the volume change of Si during charging and discharging processes.

Supramolecular liquid crystalline polymers and shape memory polymers are attracting increasing interest as materials. In this paper, we describe the development of a supramolecular liquid crystalline shape memory polyurethane (SLCSMPU) complex that exhibits both liquid crystalline properties and shape memory properties. The complex is formed by incorporating 4-hexadecyloxybenzoic acid (HOBA) into a pyridine-containing shape memory polyurethane (PySMPU). The HOBA is tethered to the PySMPU by strong hydrogen bonding between the pyridine rings and the COOH of the HOBA, forming a SLCSMPU complex. Heat treatment plays an important role in the formation of hydrogen-bonded supramolecular liquid crystalline structures in these SLCSMPU complexes. Thus, the SLCSMPU complex not only maintains the intrinsic liquid-crystalline properties of HOBA, but can also form a stable polymeric film for various shape memory applications. Additionally, the SLCSMPU complex forms a two-phase separated structure composed of an amorphous polyurethane matrix and a HOBA crystalline phase, which includes the hydrogen-bonded crystalline HOBA phase and the free HOBA crystalline phase. Therefore, a simple one-step programming process is developed that produces SLCSMPU complexes with excited triple-shape functionalities due to their multiple phase transitions, especially when the molar ratio of HOBA/BINA is less than 0.8.

Liquid-crystalline polymers and shape-memory polymers are attractive to many researchers. This paper proposes a strategy to prepare liquid-crystalline shape-memory polyurethane (LC-SMPU) composites having both liquid-crystalline properties and shape-memory properties. A series of LC-SMPU composites are successfully prepared by doping different concentrations of 4-hexadecyloxybenzoic acid (HOBA) into shape-memory polyurethanes (SMPUs). The results show that the HOBA is physically mixed with the polyurethane matrix. The doped HOBA is categorised as HOBA captured by the polyurethane chains and free HOBA in the LC-SMPU composite. A higher content of HOBA results in a higher fraction of free HOBA, and more HOBA molecules enter into the polyurethane matrix at higher annealing temperatures. The resulting LC-SMPU composites keep their intrinsic liquid-crystalline properties and the crystallisation properties of HOBA. The LC-SMPU composites contain a two-phase, separated structure: a HOBA crystalline phase and the polyurethane matrix. Thus, the LC-SMPU composites show a two-stage decrease in modulus. Finally, shape-memory tests show that the LC-SMPU composites exhibit a triple shape-memory effect; in the first step, strain recovery is associated with the glass transition of the amorphous polyurethane matrix, and in the second step, strain recovery results from the melting transition of the HOBA crystal dopants.

Shape memory materials and self-healing materials have attracted considerable attention in recent years. This paper reports the development of a liquid-crystalline shape-memory-polyurethane (LC-SMPU) composite based on SMPU and hexadecyloxybenzoic acid (HOBA) for self-healing applications. The results demonstrate that HOBA is physically mixed with SMPU resulting in a semi-crystalline reversible phase and forming LC-SMPU composites. The two-phase separated structure comprises an SMPU matrix and a HOBA phase. The HOBA phase exhibits a reversible nematic phase within a temperature range of 101–130 °C, while the SMPU matrix acts as a stable polymeric film for various applications. Both the semi-crystalline soft phase of the SMPU matrix and the HOBA crystalline phase can be used to trigger shape memory effects. The LC-SMPU composites display not only triple-shape memory behaviours but also self-healing behaviours due to the heating-induced “bleeding” behaviour of HOBA in the liquid crystalline state and their subsequent recrystallisation upon cooling.

Photo-responsive polymers attracted a great deal of interest in recent years. This paper reports a facile preparation of supramolecular shape memory polyurethane complexes from the pyridine-containing polyurethanes and azobenzene-containing mesogens. The results showed that the azobenzene-containing mesogens are grafted on the polyurethane networks via hydrogen bonds between pyridine rings and carboxyl of mesogens. The addition of azobenzene-containing mesogens greatly affected the intermolecular interactions, increasing the glass transition temperature, thermal stability, and storage modulus while promoting the micro-phase separation. The complexes exhibited multi-shape memory properties and excellent photo-thermal staged-responsive shape memory properties showing photo-responsive deformation, temporary shape fixation under visible light irradiation at room temperature and thermal-responsive shape recovery. Particularly, the photo-deformation was achieved even at 2 wt % mesogens added to the polymer network. However, the photo-response greatly increased when the content of mesogen reached 6 wt%. Finally, the proposed mechanism of photo-deformation revealed that this property is due to the photo-isomerization of azobenzene groups of the mesogens, whereas the shape recovery was ascribed to the thermal-responses of polymer networks. It is thus anticipated that these supramolecular polyurethane complexes could be widely applied in smart devices, photo-thermal sensors, and other fields.