As high-performance thermoplastic engineering plastics, polyamides (PAs) are characterized by excellent mechanical strength and good wear resistance; hence, they are commonly used as triboelectric layers in triboelectric nanogenerators (TENGs). However, most conventional PAs are derived from petrochemical monomers, and their production processes generate greenhouse gas emissions, which poses a challenge to the sustainable advancement of TENGs. In this work, a highly heat-resistant biobased polyamide (PA56T) was synthesized using biobased 1,5-diaminopentane, 1,6-diaminohexane and terephthalic acid. To enhance the processability of PA56T, aliphatic PA46 was incorporated to prepare high-performance and readily processable copolyamides (P-CoPAs) through screw processing. After three rounds of processing, P-CoPA-3 showed significantly improved melt flowability and processability, while its thermal properties (Tm = 273 °C and T5%d = 400 °C) and triboelectric output performance (Voc ∼ 30 V) remained almost unchanged, with the fabricated P-TENG maintaining robust performance even at temperatures of up to 200 °C. Furthermore, the device attained a peak power density of 2380 µW m-2, which is adequate to light up 10 LEDs and charge capacitors to 9 V within 60 s. Overall, this work offers a sustainable strategy for reliable energy devices and wearable self-powered sensors.

With the rapid development of high-frequency electronic devices toward greater integration and power density, electronic packaging materials that simultaneously offer high thermal conductivity and low dielectric loss are urgently needed. However, constructing an effective thermal conduction network typically requires high filler loadings, which in turn increase interfacial thermal resistance and raise dielectric loss. To address this challenge, a strategy is proposed that utilizes the liquid crystal orientation behavior of thermotropic liquid crystal polyarylate (LCP) to control the ordered arrangement of functionalized boron nitride (BN-G). During melt processing, highly oriented LCP molecular chains form in-situ microfibrillar structures along the shear flow direction, which align BN-G and facilitate continuous thermal conduction pathways at low filler loadings. These results demonstrate that BN-G is uniformly distributed in an ordered fashion along the in-plane direction within the LCP matrix. The LCP-BN-G composite with 20 wt% filler loading achieved an in-plane thermal conductivity of 1.45 W·m-1·K-1, representing a 196.5% increase over pure LCP, while maintaining a low dielectric constant of 3.36 and dissipation factor of 0.014 at 1 MHz. In summary, a feasible approach is provided herein for designing high-performance thermally conductive composites tailored for high-frequency and low-loss applications.

Polymers are playing important roles in the rapid development of triboelectric nanogenerators (TENGs); However, most polymers cannot meet the high requirements of thermomechanical performance; Thus, various polymeric composites are developed for triboelectric layer. These composites are hardly recycled since their reinforcements are unevenly distributed after reprocessing, which limits the sustainable development of TENGs. To solve the above challenges, in situ generated nanofiber reinforced composites (NFRCs) based on single-component liquid crystal polyarylate (LCP) are designed and prepared via a one-step polycondensation. Nonlinear naphthalene (NDA) widens the processing window of LCP without destabilizing the liquid crystal phase. The NDA-rich domains act as a matrix while the NDA-poor domains with higher rigidity form oriented nanofibers to achieve self-reinforcement. The resultant NFRCs possess high glass transition temperature (T-g > 220 degrees C) and storage modulus (E ' = 0.1 GPa at 350 degrees C), which are far beyond existing triboelectric polymers, typically T-g < 110 degrees C and E ' < 0.1 MPa (flowable) at 350 degrees C. Furthermore, NFRC-based TENG exhibits superior electrical output performance and retention rate (>90%) after reprocessing; Overall, this work offers a new design principle to prepare self-reinforced composites, which paves a way to explore high performance materials.

Thermotropic liquid crystalline polymers (TLCPs) usually act as reinforcement to prepare composites; however, poor interfacial adhesion between two materials leads to restricted enhancement in performance. Although adding a flame retardant is an effective method to extend the application fields of composites, it results in serious phase separation. To address the above challenges, a new strategy to design high-performance in-situ-reinforced composites with intrinsic flame retardancy is presented in this work. A naphthalene monomer with a kinked structure reduces the regularity of molecular chains, which improves the processability and forms a relatively flexible polymer bulk. The rest of the domains are more rigid and peculiarly form nanofiber reinforcement. The resultant composites possess high glass transition temperature (T-g > 200 degrees C), excellent processability (minimum complex melt viscosity similar to 6.4 x 10(3) Pas), and great intrinsic flame retardancy. This would be an effective solution to reconcile the contradictory processability, phase separation, and flame retardancy of composites

The notorious issue of high fire hazards, including the generation of considerable heat and melt dripping, is recognized as the bottleneck of extensive use of polyethylene terephthalate (PET). Although various techniques have been adopted for the fabrication of flame retardant PET, how to address the contradiction of flame retardancy and anti-dripping while maintaining its good processability in an environment-friendly method is still challenging. Hence, we design and prepare an intrinsic flame retardant copolyester based on PET and thermo-tropic liquid crystalline polymer (PET/TLCPx) via a simple and efficient one-step melt copolymerization to address the above challenges. On the one hand, the mesogen units not only allow copolyesters to show a typical liquid crystalline behavior with excellent processability but also constructs a highly rigid main chain to endow PET/TLCPx with outstanding thermal stability, fire resistance, and non-dripping. Furthermore, the resultant PET/TLCP3 exhibits a much lower (by 72 %) peak heat release rate than that of PET, which is attributed to the formation of a denser char layer (char yield similar to 37 %) for excellent fire resistance. Meanwhile, the melt dripping of PET/TLCPx is suppressed with the increase of complex viscosity and the growth of molecular weight due to the post-condensation during combustion. The resultant high-performance copolyesters are highly valuable for high -end applications that have strict requirements for fire safety and thermal stability, such as fire alarm and rescue systems based on triboelectric effect and shape memory behaviors.

Through the effective combination of photothermal conversion agent polydopamine (PDA) nanoparticles and epoxy acrylate polymer (EA), a new kind of near-infrared (NIR) light-triggered shape memory polymer (PDA/EA) is developed. Due to the outstanding photothermal effect of PDA, even with a very low concentration of PDA (0.1 wt.%), when exposed to an 808 nm NIR light with a power of 1 W/cm2, the temporary shapes can be fully light-responsive, recovered in 60 s. Based on dynamic thermomechanical analysis and thermal gravimetric analysis, it can be seen that the introduction of PDA is beneficial for improving dynamic mechanical properties and thermal resistance compared to EA. As an environmentally friendly and highly efficient photoactive SMP, PDA/EA has a great application prospect.

Two trifunctional phenylethynyl-terminated imide oligomers, m-TPEPA and p-TPEPA, were systematically compared with the corresponding bifunctional phenylethynyl-terminated imide oligomer, BPEPA. The non-isothermal curing kinetics, Master Plots method, and rheological behaviour of the three high performance oligomers were systematically studied by dynamic DSC, small amplitude oscillatory shear rheometry, and infrared spectroscopy. The results show that the activation energy ( E a ) depended on the extent of conversion evaluated with three different methods, and the lower E a values of the trifunctional oligomers, which may lead to different curing reactions, compared with the sustained growth of E a values of BPEPA. The chemorheological properties of the oligomers were measured and fit numerically with the dual Arrhenius model and gel model. Moreover, the degree of cure (a gel ) at the gel time (t gel ) was calculated by the value of glass transform temperature at different curing temperature combined with rheological and isothermal DSC results. According to structural changes during the curing reaction characterised using FTIR spectra, it was inferred that the structures of the cured trifunctional imide resins have cis-configurations, which may change the part of the configuration from cis to trimerisation with the lower activation energies found in the later part of the conversion, while the difunctional imide structure is trans.

A practical modifier, 4,4-bis[2-(1-propenyl)phenoxy]benzophenone (MT), has been synthesized and copolymerized with 4,4-bismaleimidodiphenylmethyene (4,4-BMI) to yield a low-temperature cure bismaleimide resin. Structural information of MT was obtained using Fourier transform infrared spectroscopy and nuclear magnetic resonance (proton and carbon) spectroscopy, elemental, and mass spectrometry analyses. The differential scanning calorimetric curve of the MT/4,4-BMI system shows two exothermic peaks at 164 degrees C and 210 degrees C, respectively. This value was compared with other polymerization reactions involving diallyl bisphenol A (DP) and diallyl bismaleimide (DBMI), with an exothermic peak at around 257 degrees C. Unlike normal bismaleimide resins with DP postcured at 250 degrees C for about 4-8 h, the MT/4,4-BMI resin was cured at 230 degrees C for a total of 6 h (i.e. MBMI-230) or at 200 degrees C for 6 h (i.e. MBMI-200). Furthermore, the resins exhibit high thermal resistance, excellent mechanical properties, and exceptionally low dielectric loss. For MBMI-230 and MBMI-200, the dielectric loss values are all in the range of 0.0024-0.0054 from 7 GHz to 18 GHz and feature excellent thermal stabilities (5% weight loss temperature (T-d5) > 415 degrees C under nitrogen atmosphere) and thermo-oxidative stabilities (T-d5 > 425 degrees C in air atmosphere). Additionally, the cured resins also display a high bending modulus (>3.2 GPa) at room temperature and an excellent mechanical stability at high temperature.

High-performance bismaleimide resin systems (here coined LBMI resin series) based on 4,4-bismaleimidodiphenylmethane, 2,4-bismaleimidotoluene, bisphenol A bisallyl ether, 4,4′-bis[2-(1-propenyl)phenoxy]benzophenone, 2-allylphenol, and cumene hydroperoxide for resin transfer molding (RTM) process with low cure and post-cure temperatures (≦180°C) have been developed. Considering the optimum formulation conditions, the injection temperature is in the range of 70–160°C, and the pot life at 100°C is determined to be approximately 100 min. After curing at 180°C for 6 h, the resins exhibit high thermal resistances, excellent mechanical properties, and exceptionally low dielectric loss. Among others, these findings render the materials suitable for the use as high-performance resins for the production of advanced composites via RTM technique and with low cure temperatures.

A series of novel modifiers for bismaleimide, bearing propenyl and phenoxy functional groups has been synthesized. Structural information of the monomers was obtained through Fourier transform infrared spectroscopy (FT-IR), nuclear magnetic resonance (NMR) spectroscopy and elemental analysis. Polymerization characteristics demonstrate that all four systems prepared have a cure temperature below 210 degrees C. This remarkably lower cure temperature compared to that of other polymerization reactions involving diallyl bisphenol A and bismaleimide (DBMI) originates from propenyl groups being present in the structures as well as their larger free volume. The rheological behaviors leading to low melt viscosities and the wide process window of the prepolymer are particularly suitable characteristics for the production of performance resin-based composite materials via resin transfer molding processes. The dynamic mechanical analysis of the materials reveals glass transition temperatures in a range between 260 degrees C and 293 degrees C. Thermal stabilities show a 5% weight loss at temperatures ranging from 363 degrees C to 428 degrees C with the production of char ranging from 38.5% to 57.6% at 800 degrees C under nitrogen. The latter is a clear indication for the excellent thermal stabilities featured by the cured resins. Furthermore, the dielectric properties exhibit a significantly lower dielectric constant and dissipation factors of the propenyl-modified cured systems compared to those of DBMI resins at 10 GHz. Copyright (C) 2015 John Wiley & Sons, Ltd.

Anisotropic and binary colloids self‐assemble into a variety of novel supracolloidal structures within the thermo‐switchable confinement of molecular microtubes, achieving structuring at multiple length scales and dimensionalities. The multistage self‐assembly strategy involving hard colloidal particles and a soft supramolecular template is generic for colloids with different geometries and materials as well as their binary mixtures. The colloidal architectures can be controlled by colloid shape, size, and concentration. Colloidal cubes align in chains with face‐to‐face arrangement, whereas rod‐like colloids predominantly self‐organize in end‐to‐end configurations with their long axis parallel with the long axis of the microtubes. The 1D microconfinement imposed on binary mixtures of anisotropic and isotropic colloids further increases the diversity of colloid‐in‐tube structures. In cube–sphere mixtures, cubes may act as additional confiners, locking in colloidal sphere chains, while a “colloidal Morse code” is generated where rods and spheres alternate in the case of rod–sphere mixtures. The versatile confined colloidal superstructures including their thermoresponsive assembly and disassembly are relevant for the development of stimulus–responsive materials where controlled release and encapsulation are desired.

Structural transformations of superparamagnetic colloids confined within self-assembled microtubes are studied by systematically varying tube-colloid size ratios and external magnetic field directions. A magnetic field parallel to microtubes may stretch non-linear chains like zigzag chains into linear chains. Non-parallel fields induce new structures including repulsive chains of single colloids, kinked chains and repulsive dimers, which are not observed for unconfined magnetic colloids in the bulk. The formed colloidal structures are confirmed via model calculations which account for tube-colloid size ratio effects and their reconfigurability with the field direction. Furthermore, structures are formed that allow controllable switching between a helical and a non-helical state. All observed field-induced transformations in microtubes are reversible provided the microtubes are not completely filled with colloids. In addition, we demonstrate magnetic field-responsive 2D crystallization by extending control over colloidal configurations in single microtubes to multiple well-aligned microtubes.

Hierarchical, bottom-up, self-organization processes of nano- and microscale building blocks constitute an important design route for stimulus-responsive materials. On page 313, Andrei V. Petukhov and co-workers demonstrate that a rich variety of novel supracolloidal structures emerge from the self-organization of various shape-anisotropic colloids and binary mixtures of isotropic and anisotropic colloids in 1D microconfinement.

High curing temperature and big brittleness are two disadvantages of heat resistant thermosetting resins. To simultaneously resolve these problems, surface functionalized fibrous attapulgite (N-ATT) was used to modify 4,4'-bismaleimidodiphenylmethane (BDM)/2,2'-diallyl bisphenol A (DBA) resin, and then a new kind of high performance nanocomposites (BD/N-ATT) were developed. The structure and properties of BD/N-ATT nanocomposites with different loadings of N-ATT were intensively studied. Results prove that the surface functionalization of attapulgite endows N-ATT has multi-effects with BD resin, and thus change the chemical and aggregation state (including crosslinking density and free volume) structures of the cross linked network, and consequently, the composites have obviously different properties from BD resin. For the composite with only 0.5 wt% N-ATT, its impact strength is about 1.6 times the value of BD resin, while the glass transition temperature and initial degradation temperature are about 25 and 20 degrees C higher than those of BD resin, respectively. The attractive properties of BD/N-ATT composites with a small loading of N-ATTs suggest that the composites have great potential in many cutting-edge fields; besides, interestingly, the method developed herein suggests a new way to develop high performance resins and related composites with simultaneously improved curing feature, toughness and thermal resistance. (C) 2013 Elsevier B.V. All rights reserved.

Three composites based on CE resin,aluminum nitride(AlN),nano AlN(n-AlN) and silicon dioxide(SiO2),and silane coupling agent(KH560) modified AlN and SiO2,coded as AlN/CE,n-AlN/CE,AlN-SiO2/CE and AlN(KH560)-SiO2(KH560)/CE composite,respectively,were prepared.The influences of the sort,size and surface nature of fillers on the thermal conductivity and dielectric properties of composites were investigated in detail.The results show that properties of fillers have great influence on the thermal conductivity of composites.When CE resin was filled by n-AlN and AlN,the resultant composites increased thermal conductivity due to the close arrangement.The composite with a higher content of AlN had higher dielectric constant.But when SiO2 was used to replace AlN,the increasement of dielectric constant was reduced.

Novel high performance UV-curable coatings based on epoxy acrylate (EA) oligomer and hyperbranched polysiloxane (HPSi) were prepared, the effect of HPSi on the processing of uncured EA/HPSi system and integrated performance of cured resins is evaluated. Results show that a small addition of HPSi can greatly decrease the viscosity of EA oliogmer, while the viscosity almost does not reduces as the content of HPSi continuously increases owing to the interaction between HPSi and EA oligomer. The integrated performance of cured resins is closely related with the content of HPSi, those resins with suitable contents of HPSi have significantly improved toughness and stiffness as well as thermal and moisture resistance. The origin of all these changes in macro-performance are investigated and proved to be resulted from the variety in the chemical structure and crosslinking density induced by the addition of HPSi. These attractive features of EA/HPSi resins suggest that HPSi is an effective multi-functional diluent for UV-curable EA resin, and the method proposed herein is a new approach to develop high performance UV-curable coatings, solvent-free resins, etc., for cutting-edge industries.

Interface is the key topic of developing advanced fiber reinforced polymeric composites. Novel advanced glass woven fabric (GF) reinforced composites, coded as GF/mBT, were prepared, of which the matrix resin was hyperbranched polysiloxane (HBPSi) modified maleimide-triazine (mBT) resin. The influence of the composition of the matrix on the interfacial nature of the GF/mBT composites were studied and compared with that of the composite based on GF and BT resin using contact angle, X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM), and dielectric properties over wide frequency and temperature ranges. Results show that the interfacial nature of the composites is dependent on the chemistries of the matrices, mBT matrices have better interfacial adhesion with GF than BT resin owing to the formation of chemical and hydrogen bonds between mBT resin and GF; while in the case of mBT resins, the content of HBPSi also plays an important role on the interfacial feature and thus the macro-performance. Specifically, with increasing the content of HBPSi in the matrix, the interlaminate shear strength of corresponding composites significantly improves, demonstrating that better interfacial adhesion guarantees outstanding integrated properties of the resultant composites.

In order to meet the increasing demands on high performance foams with excellent dielectric property by modern industries, a new type of high performance foams based on diallyl bisphenol A modified bismaleimide (BDM/BA) resin is first developed in this paper. The effects of processing parameters such as prepolymerization time and temperature, foaming temperature and time as well as the content of blowing agent on the properties and morphology of resultant foams are intensively investigated from the view of processing-property-morphology relationship. Results show that compared with BDM/BA resin, the optimum condition of prepolymerization is 140 degrees C for 60 min, and that of foaming is 160 degrees C for 35 min. Foams based on BDM/BA resin with 9 wt% AC135 have uniform cell distribution, and greatly improved dielectric property. Copyright (C) 2010 John Wiley & Sons, Ltd.