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In recent years, π-conjugated liquid crystalline molecules with optoelectronic functionalities have garnered considerable attention, and integrating these molecules into side-chain liquid crystalline polymers (SCLCPs) holds potential for developing devices that are operational near room temperature. However, it is difficult to design SCLCPs with excellent processability because liquid crystalline mesogens are rigid rods, have low solubility in organic solvents, and have a high isotropization temperature. Recently, we developed near-room-temperature π-conjugated nematic liquid crystals based on “bridged stilbene”. In this work, we synthesized a polyacrylate SCLCP incorporating a bridged stilbene that exhibited a nematic phase near room temperature and could maintain liquid crystallinity for more than three months. We conducted a thorough phase structure analysis and evaluated the optical properties. The birefringence values of the resulting polymers were higher than those of the corresponding monomers because of the enhanced order parameters due to the polymer effect. In addition, the synthesized polymers inherited mesogen-derived AIE properties, with high quantum yields (Φfl = 0.14–0.35) in the solid state. It is noteworthy that the maximum fluorescence wavelength exhibited a redshift of greater than 27 nm as a consequence of film formation. Thus, several unique characteristics of the SCLCPs are unattainable with small molecular systems.

Additive manufacturing allows for the production of complex components using various types of materials such as plastics, metals and ceramics without the need for molding tools. In the field of high-performance polymers, semi-crystalline polymers such as polyetheretherketone (PEEK) or amorphous polymers such as polyetherimide (PEI) are already successfully applied. Contrary to semi-crystalline and amorphous polymers, thermotropic liquid crystalline polymers (LCPs) do not change into an isotropic liquid during melting. Instead, they possess anisotropic properties in their liquid phase. Within the scope of this work, this special group of polymers was investigated with regard to its suitability for processing by means of fused filament fabrication. Using an LCP with a low melting temperature of around 280 °C is compared to processing an LCP that exhibits a high melting temperature around 330 °C. In doing so, it was revealed that the achievable mechanical properties strongly depend on the process parameters such as the direction of deposition, printing temperature, printing speed and layer height. At a layer height of 0.10 mm, a Young’s modulus of 27.3 GPa was achieved. Moreover, by employing an annealing step after the printing process, the tensile strength could be increased up to 406 MPa at a layer height of 0.15 mm. Regarding the general suitability for FFF as well as the achieved uniaxial mechanical properties, the LCP with a low melting temperature was advantageous compared to the LCP with a high melting temperature.

Bonded permanent NdFeB magnets are useful in numerous applications, including electric vehicles, and the demand is steadily increasing. A major drawback is corrosion due to inadequate wetting of the magnetic particles by liquid polymers such as polyphenylene sulfide or polyamide. Recently reported methods for corrosion inhibition are summarized, and their applicability is critically evaluated. The phosphorylation of magnetic particles inhibits corrosion but does not enable appropriate properties in harsh environments. The same applies to metallic coatings, which usually contain aluminum and zinc. Advanced epoxy adhesives are a promising solution, although some authors have reported inadequate corrosion resistance. The application of composite coatings seems like an appropriate solution, but the exact mechanisms are yet to be studied.

Circularly polarized luminescence (CPL) materials have shown great application potential in the fields of three-dimensional displays, bioimaging, and information encryption and decryption. The chirality enhancement of CPL by a physical chiral environment, involving the delivery of structural asymmetry from helical architectures to luminescent molecules through electromagnetic field resonance, represents an innovative approach for constructing high-performance CPL materials. Liquid crystal polymers (LCPs), possessing helical superstructures, show great potential in constructing CPL systems. By modulating the chirality transfer from the helical structural environment of LCPs to luminescent sources via distinct strategies, the CPL properties of LCP-based composites are readily generated and tailored. This review summarizes the newest construction strategies of LCP-based CPL materials and provides a perspective on their emerging applications and future opportunities. This review can deepen our understanding of the fundamentals of chirality transfer and shed light on the development of functional chiral luminescent materials.

Fibre-reinforced polymer structures are often used when stiff lightweight materials are required, such as in aircraft, vehicles and biomedical implants. Despite their very high stiffness and strength 1 , such lightweight materials require energy- and labour-intensive fabrication processes 2 , exhibit typically brittle fracture and are difficult to shape and recycle 3 , 4 . This is in stark contrast to lightweight biological materials such as bone, silk and wood, which form by directed self-assembly into complex, hierarchically structured shapes with outstanding mechanical properties 5 – 11 , and are circularly integrated into the environment. Here we demonstrate a three-dimensional (3D) printing approach to generate recyclable lightweight structures with hierarchical architectures, complex geometries and unprecedented stiffness and toughness. Their features arise from the self-assembly of liquid-crystal polymer molecules into highly oriented domains during extrusion of the molten feedstock material. By orienting the molecular domains with the print path, we are able to reinforce the polymer structure according to the expected mechanical stresses, leading to stiffness, strength and toughness that outperform state-of-the-art 3D-printed polymers by an order of magnitude and are comparable with the highest-performance lightweight composites 1 , 12 . The ability to combine the top-down shaping freedom of 3D printing with bottom-up molecular control over polymer orientation opens up the possibility to freely design and realize structures without the typical restrictions of current manufacturing processes. 3D printing of liquid-crystal polymers can create lightweight hierarchical structures with very high stiffness and toughness.

A 2 × 2 ultra-wideband MIMO flexible antenna with a low profile and good isolation was designed for Internet of Things (IoT) realms and wearable devices. The antenna elements were placed on a novel flexible substrate of liquid crystal polymer (LCP) with compact dimensions fed by a coplanar waveguide (CPW). In order to ameliorate isolation, the cross-shaped decoupling branches were placed among the antenna elements. The proposed UWB antenna can operate from 2.9 GHz to 10.86 GHz with a good reflection coefficient of S11 < −10 dB as well as a high isolation better than 22 dB. Its operating bands include 5G, WiFi, X-band, etc. Moreover, the parameters of diversity performance were also tested. These parameters included an average gain of approximately 4 dB, a low ECC of less than 0.01, and good diversity gain of 9.999. The flexible MIMO antenna performs well in bending and on-body conditions. To sum up, the antenna has good prospects in IoT applications and wearable fields.

Fiber-shaped electrical heaters with high flexibility and excellent adaptability make an ideal candidate for the application of wearable electronics but still suffer from low strength and poor durability. Herein, an all-in-one Joule-heating fiber capable of outstanding mechanical properties, good heating efficiency, and long-term stability is reported by using polymer-assisted metal deposition to firmly coat Cu nanoparticles on high-performance liquid crystal polymer (LCP) fibers. Taking advantage of LCP, the resultant fibers exhibit a satisfying temperature threshold (up to 200 °C) and immense strength (2.94 GPa). By virtue of dense and continuous Cu film, these fibers show low electrical resistance (5.51 Ω/cm) and an ultrafast response rate (12.6 °C·s−1) at low supplied voltages (0.5–3.5 V). Benefiting from the levodopa/polyethyleneimine interface design, such fibers maintain nearly constant resistance after repeatable bending, folding, and even washing (50 cycles). Based on the above-mentioned merits, a wearable patch with a Joule-heating function is knitted by using as-made fibers to offer therapeutic benefits for human body joints. This work demonstrates prospective potential for enriching the challenging applications of fiber-shaped electrical heating systems.

It is highly expected to develop a simple and effective method to reinforce polyamide 6 (PA6) to enlarge its application potential. This is challenging because of frequently encountered multi-component phase separations. In this paper, we propose a novel method to solve this issue, essentially comprising two steps. Firstly, a kind of poly (amide-block-aramid) block copolymers, i.e., thermotropic liquid crystalline polymer (TLCP)-polyamide 6 (TLCP-PA6), that contains both rigid aromatic liquid crystal blocks, and flexible alkyl blocks were synthesized. It is unique in that TLCP is chemically linked with PA6, which is advantageous in excellent chemical and physical miscibility with the precursors of monomer casting polyamide 6 (MCPA6), i.e., ε-caprolactam. Secondly, such newly synthesized block copolymer TLCP-PA6 was dissolved in the melting ε-caprolactam, and followed by in situ polymerization to obtain composite polymer blends, i.e., MCPA6/TLCP-PA6. The thermodynamic, morphological, and crystalline properties of MCPA6/TLCP-PA6 can be easily manipulated by tailoring the loading ratios between TLCP-PA6 and ε-caprolactam. Especially, at the optimized condition, such MCPA6/TLCP-PA6 blends show an excellent miscibility. Systematic characterizations, including nuclear magnetic resonance (NMR), Fourier-transform infrared spectroscopy (FT-IR), differential scanning calorimeter (DSC), and polarizing optical microscope (POM), were performed to confirm these statements. In view of these results, it is anticipated that the overall mechanical properties of such PA6-based polymer composites will be satisfactory, which should enable applications in the modern plastic industry and other emerging areas, such as wearable fabrics.

An aromatic copolyester liquid crystal polymer (LCP) was introduced into carbon-fiber-reinforced polyamide–polyurethane (CF/PA-PU) composites through melt blending to improve the tribological properties of the composites. The effects of LCP on the mechanical, processing, and thermal properties of CF/PA-PU composites were compared to those of commonly-used graphite (Gr). The results showed that at 5 wt.% LCP content, the coefficient of friction (COF) was decreased by 16.06%, and the wear rate by 32.22% in the LCP/CF/PA-PU composite compared to the CF/PA-PU composite. Furthermore, using LCP instead of Gr showed significantly improved mechanical properties and reduced processing viscosity. The tensile strength of 5%LCP/CF/PA-PU composite could reach 99.08 MPa, while the equilibrium torque was reduced, being 26.85% higher and 18.37% lower than those of CF/PA-PU composite, respectively. The thermal stability of LCP/CF/PA-PU composites was also enhanced. The addition of 5 wt.% LCP to CF/PA-PU composite increased the initial decomposition temperature by 14.19% compared to CF/PA-PU. In sharp contrast, the addition of Gr increased equilibrium torque and actual processing temperature leading to processing difficulties and instability. This approach offers a novel strategy for tribological applications and tackles the problem of high viscosity in CF/PA-PU composites.

Vividly colored cholesteric liquid crystal polymer network (CLCN) patterns based on epoxy resin are used in decorative and anti-counterfeiting applications. These films are typically prepared via cationic photopolymerization and post-polymerization to achieve a high cross-linking degree. In this work, the cross-linking degree is controlled by varying the UV irradiation dosage during photopolymerization. Following this, the reflection band of the CLCN film changes after removing non-cross-linked compounds with acetone. Leveraging the low cationic polymerization rate and the chain termination capability of methanol, a structurally colored CLCN film with regionally tailored cross-linking was fabricated. With the treatment of acetone, a colorful pattern was observed. Moreover, upon immersion in methanol, the film swelled, revealing a colorful pattern. After the evaporation of methanol, the pattern disappeared. Consequently, this CLCN film holds significant potential for information encryption applications.