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The mechanical properties of thermally conductive composites are the key to realize their applications. Strength of materials is of significance, furthermore the toughness of materials also should attract more concern. Actually, few researchers have reported the simultaneous improvement of strength and toughness of anisotropic thermally and electrically conductive composites. Therefore, this study aims to obviously improve the in-plane thermal and electrical conductivities of nylon composites, which display superior tensile strength and toughness, compared to other thermally conductive composites. The nylon composite papers, prepared through a facile method involving vacuum-assisted filtration and compression molding processes, present a laminate structure and compact graphene nanoplatelet (GNP) stacks inside composites. On account of the special structure, the nylon composite papers show a super-high in-plane thermal conductivity of 16.0 W m−1 K−1 and electrical conductivity of 18.0 S cm−1 at a filler loading of 14.6 wt%. Surprisingly, the composite papers still exhibit a high strength of 48.3 MPa, which is comparable to that of a pure nylon film. In addition, the elongation at break of the composite paper with 14.6 wt% GNPs is as high as 34.2%, ultimately endowing the composite papers with a good toughness of 13.15 MJ m−3. The nylon composite papers successfully achieve the integration of excellent thermal and electrical conductivities, and superior strength and toughness, showing huge application values in the field of intelligent electronic device.

Composites with high thermal conductivity and excellent electromagnetic interference (EMI) shielding performance are in urgent demand in the fields of wireless communication technologies and portable intelligent electronic devices. However, it remains a great challenge to simultaneously improve thermal conductivity and EMI shielding effectiveness (SE) for polymer composites. This work reports a feasible and scaled method relating to vacuum-assisted filtration and compression-molding to fabricate nylon/graphene nanoplatelet (GNP) composite papers using commercial nylon gauze and GNPs. The results show that the composite papers exhibit good flexibility and multifunctional performances. At 11.8 wt% GNPs, the three-layered composite nylon/GNP paper, which had a thickness of about 180 μm, showed high thermal and electrical conductivities of 15.8 W m−1 K−1 and 24.3 S cm−1, respectively, and an outstanding EMI SE of 58.1 dB at the X-band (8.2–12.4 GHz). The compromise of thermal conductivity and EMI SE of the composite paper is much greater than that of other multifunctional composites reported in the literature. Specifically, the composite papers also show greatly enhanced hydrophobicity and flame resistance and satisfactory mechanical properties. To sum up, this work paves the way for the real engineering application of nylon-based composite papers in next-generation electronic devices.

Polymer nanocomposites filled with one-dimensional “reelable” carbon-based nanoparticles can exhibit a high dielectric constant (e′) with a small quantity of nanoparticles. However, this kind of na...

Strong rigidity, low thermal conductivity, and short of multi-driven capabilities of form-stable phase change materials (FSPCMs) have limited their practical utilization. Herein, we report a shape-adaptable FSPCM with the coinstantaneous light/electro-driven shape memory properties and light/electro-to-thermal energy storage performance. The FSPCM is fabricated by incorporating the poly(ethylene glycol) (PEG) into the cellulose nanofiber/graphene nanoplatelet (GNP) hybrid-coated melamine foam (CG@MF). The CG@MF/PEG FSPCMs show a good encapsulation effect, enhanced thermal conductivity, and large melting enthalpy (178.9 J g-1). Due to the high elasticity of MF and the excellent photothermal conversion and electrical conductivity of the GNP network, the CG@MF/PEG FSPCMs exhibit a remarkable light/electro-driven shape memory effect by activating the phase change process of PEG. Meanwhile, the CG@MF/PEG FSPCMs can effectively convert light or electric energy into heat energy and reposit the converted energy during the phase change process. Furthermore, the CG@MF/PEG FSPCMs possess excellent multiresponsive self-adhesion properties. A light-sensitive, shape-adaptable, and thermal-insulating container is further explored. This study provides routes toward the development of multiresponsive shape-adaptable FSPCMs for energy storage applications.

Electrically conductive polymer composites (CPCs) are potential alternatives to conventional strain gauges due to their tunable sensitivity and strain ranges. Currently, to achieve very high piezoresistive sensitivity in thermoplastic-based CPCs with Gauge factors

A fast light-actuated shape memory polymer (SMP) composite with greatly enhanced photothermal conversion and mechanical stiffness was prepared by incorporating gold nanoparticle/reduced graphene oxide (AuNP-RGO) hybrids into cross-linked poly(e-caprolactone) (PCL). The AuNP-RGO hybrids with AuNPs uniformly anchored on RGO sheets were obtained in a water/n-butylamine system. Due to the homogeneous dispersion of AuNP-RGO in PCL matrix and the synergistic effect of photothermal conversion, the AuNP-RGO hybrids imparted the PCL with fast near-infrared (NIR) light-actuated shape recovery effect, and the light-actuated shape recovery speed could be accelerated via the increase of AuNP loading on RGO sheets. Moreover, the SMP composites possessed high shape recovery stress due to the incorporation of AuNP-RGO, thus they could be used as heavy-lift actuators. This SMP composites with enhanced light responsivity and mechanical properties are believed to have great potential in many fields such as light energy harvesting and remote-controlled actuators.

Polymeric dielectric materials recently attract much attention due to their good comprehensive performances. However, it is still challenging to prepare polymeric dielectric materials with high dielectric constant, low dielectric loss and high breakdown strength. In this work, insulated polyimide (PI) interlayer with nanoscale thickness was coated on the surface of barium titanate (BaTiO3, BT) through the in-situ polymerization and subsequent thermal imidization treatment. The hybrid nanoparticles exhibited the typical ‘core-shell’-like structure with strong interfacial interaction between BT and PI. Different from the serious aggregation of BT nanoparticles, the PI@BT nanoparticles exhibited good dispersion in the poly(vinylidene fluoride) (PVDF) composite. There was strong interfacial interaction between PI and PVDF, which resulted in the decrease of crystallinity of the PVDF matrix at relatively high filler content. The flexible PVDF/PI@BT composites exhibited largely enhanced dielectric constant, suppressed dielectric loss and enhanced breakdown strength compared with the common PVDF/BT composites. It was suggested that the intense interfacial polarization at the interface between PI and BT contributed to the largely enhanced dielectric constant while the reduced interfacial polarization at the interface between PI and PVDF contributed to the suppressed dielectric loss. This work demonstrates that the nanoengineering of the interface between BT and PVDF using PI is an alternative way to fabricate the dielectric materials with excellent comprehensive performances.

In this work, three kinds of boron nitride (BN) particles with different sizes were combined with carbon nanotubes (CNTs) to prepare the poly(vinylidene fluoride) (PVDF) composites. The dispersion states and the hybrid network structure of fillers were investigated. The results showed that the dispersion states of CNTs were greatly influenced by the size of BN particles. Relatively high density of hybrid network structure of fillers was obtained in the ternary composites containing the smallest BN particles (0.16 μm), while the composites containing the biggest BN platelets (22.02 μm) showed the low density of the hybrid network structure. Thermal conductivity measurements showed that BN particles with moderate size (8.70 μm) were the most appropriate filler to construct the highly efficient thermal conductive path with CNTs and in this condition, the ternary composites exhibited the highest thermal conductivity.

Phase change materials (PCMs) have wide applications in many fields and they are thought to be one of the highest potential materials in the future. Developing advanced PCMs faces various problems, such as low thermal conductivity, poor shape stability and single energy conversion pattern, etc. In this work, novel composite PCMs were fabricated based on the commercial melamine foam (MF) incorporated by the graphene oxide (GO) and graphene nanoplatelets (GNPs). After hydrothermal reaction and carbonization, the composite aerogel still maintained the three-dimensional (3D) composite framework structure with reduced GO (rGO) and GNPs covering on the carbonized MF framework. The composite PCM samples exhibited high shape stability without leakage under the load of 265 times of its own mass at temperature much higher than the phase change temperature of paraffin wax (PW), high phase change enthalpy retention rate (nearly 100% of PW), high thermal conductivity (1.46 W/m·K) and electrical conductivity (2.787 S/cm) at a filler content of 4.89 wt%. Moreover, the composite PCM samples have excellent light-to-thermal and electric-to-thermal energy conversion abilities, which endow the composite PCMs with great potential in diverse applications, such as the energy saving and heat preservation of building and temperature protection of microelectronic devices, etc.

Polyamide-based composites with segregated Carbon nanotube (CNT) network were prepared to achieve a high dielectric constant with an ultralow loading of CNTs. Specially, the polypropylene (PP) was introduced into the segregated CNT network to tailor the CNT dispersion. More importantly, the PP layer formed between two neighbored CNTs can enhance the interfacial polarization and suppress the electron conduction, leading to a higher dielectric constant while maintaining the dielectric loss at a low level. In this work, CNT segregated structure was firstly applied to achieve polymer composites with high dielectric constant but low loss.

Polystyrene (PS) composites containing graphene nanoplatelets (GNPs) and carbon nanofibers (CNFs) were prepared through solution compounding processing. The results showed that more compact network structure was formed in the ternary PS/GNP/CNF composites, and the composites exhibited apparently enhanced heat resistance compared with the pure PS sample. Conductive properties measurements showed that largely reduced percolation threshold was achieved for the ternary PS/GNP/CNF composites. Furthermore, the PS/GNP/CNF composites had good thermal conductivity. At GNP content of 2 vol% and CNF content of 5.5 vol%, the thermal conductivity was enhanced to 1.12 W/mK, which was 522% higher than that of the pure PS sample. The potential application of the PS composites as the material of heat radiator was also evaluated, and the results showed that the composites exhibited excellent heat transferring ability. This work indicates that the PS/GNP/CNF composites may be used in the field relating to high temperature and load conditions.

Phase change materials (PCMs) exhibit great potential applications in many fields, such as energy-saving building, solar energy harvesting, waste heat utilization, constant temperature protection and thermal management of microelectronic devices. In this work, we proposed a facile and novel method to prepare the composite PCMs. Through the combination of pre-refrigeration and freeze-drying techniques using the microcrystalline cellulose (MCC)/graphene nanoplatelets (GNPs) hydrogels, which were firstly prepared through solution compounding, gelling and solvent exchanging successively, the porous MCC/GNP aerogels with highly oriented stacking of MCC/GNP were successfully obtained. The composite PCMs based on the highly anisotropic MCC/GNP aerogel and polyethylene glycol (PEG) exhibited relatively high thermal conductivity (1.03 W/mK) at low GNP content (1.51 wt%), high latent heat (182.6 J/g) which was 99.84% of pure PEG, excellent encapsulation ability and mechanical stability. Further results showed that the composite PCMs exhibited excellent solar energy harvesting/electrical energy transformation, storage and release abilities. In addition, a simple heating device was designed to verify the application of the composite PCMs as the temperature protection element. The measurements showed that the presence of the PCMs prevented the rapidly rising of temperature during the heating process while maintained the temperature at relatively high level in a long time during the cooling process.

Developing highly efficient and multifunctional membranes toward oil adsorption and oil/water separation is of significance in oily wastewater treatment. Herein, a novel electrospun composite membrane with dual-scaled porous structure and nanoraised structure on each fiber was fabricated through electrospinning using biodegradable polylactide (PLA) and magnetic γ-Fe2O3 nanoparticles. The PLA/γ-Fe2O3 composite membranes show high porosity (>90%), superhydrophobic and superlipophilic performances with CH2I2 contact angle of 0°, good water adhesion ability like water droplets on a petal surface, excellent anti-icing performance, and good mechanical properties with a tensile strength of 1.31 MPa and a tensile modulus of 11.65 MPa. The superlipophilicity and dual-scaled porous structure endow the composite membranes with ultrahigh oil adsorption capacity up to 268.6 g/g toward motor oil. Furthermore, the composite membranes also show high oil permeation flux up to 2925 L/m2 h under the force of gravity. Even for oil/water emulsion, the composite membranes have high separation efficiency. We expect that the PLA/γ-Fe2O3 composite membranes can be used in oily wastewater treatment under various conditions through one-off adsorption or continuous oil/water separation, especially under low environmental temperature condition.

Polymer dielectric composites have widespread applications in many fields ranging from energy storage, microelectronic devices, and sensors to power driven systems, etc. and attract much attention of researchers. However, it is still challenging to prepare advanced polymer dielectric composites with a high dielectric constant (e′), low dielectric loss (tan δ) and simultaneously high breakdown strength (Ebd). In this work, conductive polypyrrole (PPy) nanoparticles were in situ synthesized in a reaction system containing the common barium titanate (BaTiO3, BT) or hydroxylated BaTiO3 (BTOH) particles, and then the PPy@BT and PPy@BTOH composite particles were incorporated into poly(vinylidene fluoride) (PVDF) to prepare the composites. The morphologies and microstructures of the PPy@BT and PPy@BTOH composite particles and the corresponding PVDF composites were comparatively investigated. The results showed that the PPy@BTOH composite particles had a ‘mulberry’-like morphology with a rough surface and the self-assembled structure could be maintained in the PVDF composites, which was apparently different from the PVDF/PPy@BT composites, in which most of the PPy nanoparticles dissociatively dispersed in the PVDF matrix. Electrical conductivity measurements showed that at high particle content (≥20 wt%), the PPy@BTOH composite particles endowed the composites with lower electrical conductivity compared with the PPy@BT composite particles. Dielectric property measurements showed that the ‘mulberry’-like PPy@BTOH composite particles endowed the PVDF composites with extremely high e′, ultralow tan δ and high Ebd compared with the PVDF/PPy@BT composites with dissociatively dispersed PPy nanoparticles and BaTiO3 particles. The polarization and loss mechanisms of the composites were then proposed based on the morphologies and the microstructures of the composites. This work provides an alternative way to fabricate functional dielectric particles through trace functional groups inducing in situ polymerization of conductive polymers, and these particles can be used to fabricate advanced dielectric composites.

Phase change materials (PCMs) exhibit wide application prospects in many fields related to energy utilization and management and attract increasing interest. In this work, through the graphene oxide (GO)-assisted dispersion technology, GO/boron nitride (BN) nanosheets were incorporated into melamine foam and successfully deposited on the surface of the foam framework after hydrothermal reaction. Through the following freeze-drying and carbonization treatment, the composite MF/rGO/BN aerogels were obtained with integrated hybrid rGO/BN frameworks. The composite PCMs were prepared through encapsulating polyethylene glycol (PEG) within the hybrid aerogels. The encapsulation stability and thermal properties of the composite PCMs were systematically investigated. The composite PCM sample containing the highest content of rGO/BN exhibited excellent encapsulation stability, high thermal conductivity (up to 0.79 W m-1 K-1), high phase change enthalpy (160.7 J g-1) with the retention of 90.8% of the pure PEG, and excellent chemical and thermal stability. Further results clearly showed that the composite PCMs had excellent light-to-heat energy transition ability and could be used as a thermal management component to suppress the overheating of devices during the operation process, or to supply energy for thermoelectric devices under emergency conditions to ensure a continuous power supply sustained for a certain time until the safeguard procedures are adopted.

Helical carbon nanotube (HCNT) is a vital member of carbon nanomaterials, but little effort was devoted to explore its unique characteristics and applications during the past few decades. Here, we report an organic thermoelectric composite with an excellent photothermoelectric (PTE) effect by conformally wrapping polypyrrole (PPy) on the intricate surface of HCNTs, which have been confirmed to have remarkable near-infrared (NIR) photothermal conversion capability and ultralow heat transportation characteristics. The results indicate that with the increasing HCNT content, PPy shell thickness reduces and exhibits denser as well as partial orientation, while the inter-ring angle slowly decreases and the bipolaron becomes dominant in carrier composition gradually. Consequently, the Seebeck coefficient increases monotonically, whereas the electrical conductivity remains nearly invariant. The final composite combines the benign thermoelectric properties, excellent photothermal response performance, and the lowest thermal conductivity of the carbon-based thermoelectric composite yet reported (0.064 W m-1 K-1). A single strip NIR light-stimulated adjustable delay switch was designed and fabricated, with the open-circuit voltage and short-circuit current under a 400 mW cm-2 NIR-stimulated approach to 720 μV and 62 nA with the discrepancy of consecutive periodic output signals less than 4.2%, exhibiting incredible stability and reliability and demonstrating the highest output voltage of a single strip among the reported organic PTE composite at room temperature. Our work fills in a gap of HCNT research, which hitherto existed in the PTE and thermoelectric field.

The hybrid networks of cellulose nanocrystals (CNCs) and graphene nanoplatelets (GNPs) were constructed in polyethylene glycol (PEG) through the common solution compounding processing, in which GNPs provided the thermally conductive path while CNCs restricted the leakage of PEG during the phase transition. The results showed that CNCs greatly enhanced the shape stability of the composite phase change materials (PCMs) while thermal conductivity was still maintained at high level. At the contents of 8 wt% (CNCs) and 4 wt% (GNPs), the enthalpy of the composite PCM was 145.5 J/g, which was 88 % of pure PEG, and the thermal conductivity was 2.018±0.067 W/m K about 563.7 % higher than that of pure PEG. Furthermore, the composite PCMs exhibited outstanding light-thermal and electro-thermal conversion capabilities. Furthermore, the composite PCMs could be designed as the temperature stabilizing component exhibiting intelligent adaptive thermal management role, providing stable temperature condition for electronic devices in extreme environment.

Tailoring the distribution of nanoparticles and further constructing effective microcapacitors in polymer blends are important issues for developing high-performance polymer dielectric nanocomposites. The common method to control the selective localization of nanoparticles in an immiscible polymer blend is relatively difficult and it easily results in the accumulation of nanoparticles in one component, which usually leads to a dramatic increase of the dielectric loss in the nanocomposites. In this work, a novel strategy based on step-by-step crystallization has been proposed to tailor the refined distribution and dispersion of carbon nanotubes (CNTs) in a melt-miscible blend poly(butylene succinate)/poly(vinylidene fluoride) (PBS/PVDF) through the crystallization-induced phase separation and the engineered interfacial affinity between CNTs and polymer components to acquire high dielectric constant and low dielectric loss. The results reveal that PBS is excluded along the growth front of PVDF spherulites and locates in the margin areas of PVDF spherulites during the step-by-step crystallization process. Moreover, because of the higher interfacial interaction between CNTs and PBS, CNTs are located in the PBS-rich domain, resulting in a high concentration of CNTs in the interspherulites of PVDF. Thus, the dielectric constants of the nanocomposites are greatly improved by nearly 5-24 times compared with the nanocomposites achieved by quick cooling and, simultaneously, the dielectric loss of the nanocomposites is still maintained at a low level. This work shows that the step-by-step crystallization method can be used to fabricate the nanocomposites with a synergistic increase in the dielectric performance due to the formation of a refined microcapacitor assembly. To the best of our knowledge, this is the first report to show that the dielectric constant of the nanocomposites can be greatly enhanced just through the crystallization-optimized distribution and dispersion of CNTs in immiscible polymer blends, and it possibly gives a new technical route for the fabrication of advanced dielectric composites.

Organic phase change materials (OPCMs) play a great role in energy management owing to their large phase change enthalpy, but their intrinsic low thermal conductivity (TC) and bad encapsulation severely restrict their applications. To overcome these problems, we developed a novel but feasible method to fabricate a graphene nanoplatelet (GNP) aerogel with compact and oriented stacking in-plane walls and many through-plane bridges via melamine foam (MF) and cellulose nanofiber (CNF) co-mediated assembly of GNPs. After impregnating paraffin wax (PW), the composite PCMs exhibit a high TC of 1.42 W m−1 K−1 at only a GNP content of 4.1 wt%, increasing by 407% compared with pure PW, and simultaneously nearly no reduction of the phase change enthalpy of PW. Meanwhile, this kind of composite PCM can not only show excellent light-to-thermal and electric-to-thermal transition ability, but also be applied in delay switch devices with satisfactory results.

Shape memory polymers (SMPs) are a type of smart materials that can recover to the original shape from a set temporary shape under external stimulus, but SMPs are prone to be damaged during repeated deformation and recovery. Therefore, it is of great significance to improve the self-healing ability of SMPs. In this work, ethylene-vinyl acetate copolymer (EVA)/polycaprolactone (PCL)/polypyrrole (PPy) blend composites were prepared via simple melt blending. In this system, PPy nanoparticles, as photothermal fillers, selectively distributed in the PCL component, enable the EVA/PCL blend with a co-continuous structure to exhibit excellent photo-induced shape memory performance with a shape recovery ratio of 100%. Thanks to the excellent photothermal effect of PPy nanoparticles and the melting and recrystallization behaviors of linear EVA and PCL chains, the blend composites also exhibit outstanding photo-induced self-healing performance for different forms of damage, and the considerable healing efficiencies for the bent, scratched and cut samples reach 85.68%, 94.63% and 86.49%, respectively. Compared with the traditional thermal-induced self-healing shape memory composites, near infrared (NIR) irradiation can not only remotely manipulate the shape memory behavior of these composites, but also can accurately and selectively heal the damaged areas without distinct impact on the performance of intact areas. The above dual functions, along with the comprehensive performances and simple preparation process of these materials, enable the EVA/PCL/PPy blend composites to be the ideal candidates for many potential applications, including soft robots, smart packaging, biomedical devices, etc.

In this work, novel functionalized poly( l -lactide) (F-PLLA) porous fibers were fabricated through electrospinning using the PLLA/methylene chloride (CH2Cl2)/N,N-dimethylformamide (DMF) solution containing diethylenetriamine (DETA) and γ-aminopropyltriethoxysilane (KH-550). The effects of PLLA, DETA and KH-550 contents on the morphologies of the electrospun fibers were systematically investigated, and the results showed that at PLLA, DETA and KH-550 contents of 20% w/v, 2 wt% and 3 wt%, respectively, the electrospun F-PLLA fibers exhibited the homogeneous distribution of fiber diameters and the homogeneous porous structure on the fiber surface. Nitrogen-containing groups were successfully introduced to the electrospun fibers, which induced the great improvement of the hydrophilicity of the membrane surface. Adsorption measurements showed that the electrospun F-PLLA membrane had good adsorption ability toward Congo red (CR), and the adsorption capacity at room temperature was enhanced in 16 times compared with the common PLLA fiber membrane, and the maximum adsorption capacity was 135.7 mg g−1. Furthermore, the adsorption behavior could be well described by the pseudo second-order model. Oil/water separating measurements showed that the electrospun F-PLLA membrane exhibited high separation efficiency and the maximum water fluxes were 2018 and 1861 L m−2 h−1 in separating non-emulsified and emulsified oil/water system under atmospheric pressure, respectively.

Fe promoted structured mesoporous anodic AlOOH (Fe/a-AlOOH) with dominant facets were developed and a series of a-AlOOH, Pt/a-AlOOH and Pt/Fex/a-AlOOH catalysts were prepared for formaldehyde oxidation at room temperature. The activities of AlOOH, Pt/a-AlOOH and Pt/Fex/a-AlOOH were compared. The results show that the Pt1.2/Fe3.8/a-AlOOH catalyst exhibits the best catalytic performance at 25 ℃ with CO2 conversion of 80% and 100% at 45 °C. The analyzation by XRD, TG and FTIR indicates that two kinds of crystal facets, AlOOH and FeOOH, are exposed on the surface of Pt1.2/Fe3.8/a-AlOOH which improve HCHO catalytic performance of the support. The catalytic performance of the selected mesh Pt/Fe/a-AlOOH catalyst was evaluated in the 3 m3 air cabin. The results show that in the condition of 1.30 m/s cross section velocity (V), 0.3–1 ppm formaldehyde (inlet concentration) can be oxidized to 0.08 ppm (indoor air quality standard) in 25 min over Pt1.2/Fe3.8/a-AlOOH mesh catalyst which is just 200 × 200 × 0.4 mm3 with the weight of 21.7 g.

Polymeric dielectric composites have wide applications in many fields ranging from wearable devices, sensors to energy storage. In this work, a novel kind of hybrid particles with ‘core-shell’-like structure were fabricated via the polydopamine-assisted deposition technology, in which the tetra-pod zinc oxide whisker (T-ZnOw) was the ‘core’ and the two-dimensional graphene oxide (GO) was the ‘shell’, while polydopamine (PDA) was the adhesion layer between T-ZnOw and GO. With the aid of PDA adhesion layer, the ‘core-shell’-like structure of the hybrid GO/PDA@T-ZnOw particles could be maintained in the poly(vinylidene fluoride) (PVDF) composites. Dielectric property measurements showed that the hybrid particles could be an excellent candidate to prepare the dielectric composites with excellent dielectric properties. There was a critical particle content (2.0–2.5 wt%) at which the composites exhibited the maximum dielectric constant and relatively low dielectric loss. Further results showed that GO and PDA@T-ZnOw particles had tremendous synergistic effect in enhancing the dielectric properties of the composites. The mechanisms for the largely enhanced dielectric constant were mainly related to the multiple interfaces in the composites, including the interfaces between GO and PVDF, between GO and PDA and between PDA and T-ZnOw, which provided more probability for interfacial polarization of the composites in the electrical field. This work presents a guideline to design high-performance dielectric composites with construction of the multiple interfaces.

In this work, poly(vinylidene fluoride)/poly(methyl methacrylate) (PVDF/PMMA) blend (50/50, wt/wt) and its blend composites containing carbon nanotubes (CNTs, 0.2 and 0.5 wt%) were prepared. Two types of PMMA with relatively large (PMMA-L) and small (PMMA-S) molecular weights were used to prepare the materials. It was observed that PVDF had higher crystallization ability in the samples containing PMMA-S. CNTs exhibited nucleation effect on the crystallization of PVDF and their nucleation efficiency was influenced by the molecular weight of PMMA. Rheological measurements showed that concentration fluctuation occurred during the melt annealing process even if the blend should be miscible at this temperature range, and more apparent concentration fluctuation was observed for the samples containing PMMA-S. Incorporating CNTs restrained the concentration fluctuation of the blend under the shear condition. Further results showed that larger concentration fluctuation in the melt state facilitated the higher crystallization ability of PVDF in the subsequent cooling process.

In this work, a small quantity of carbon nanofibers (CNFs) were incorporated into polypropylene/ethylene-propylene-diene terpolymer (PP/EPDM) blends. The effects of CNF content on the processing flowability, the microstructure of PP matrix and the morphology of elastomer particles were investigated. The results showed that the processing flowability of the material was not apparently influenced. The straight CNFs selectively located in the PP matrix and exhibited oriented dispersion along the flow direction of melt during the injection molding processing. CNFs exhibited nucleation effect on crystallization of PP. Homogeneous EPDM particles with smaller particle diameters were obtained in the blend composites. Mechanical properties measurements showed that the largely enhanced fracture toughness was achieved for the blend composites and the brittle-ductile transition was induced at lower EPDM content. Specifically, incorporating only 0.2 wt% CNFs into the PP/EPDM (85/15), the impact strength was enhanced about 246%. Further results showed that for the blend which exhibited brittle-fracture feature, the brittle-ductile transition could also be induced with increasing CNF content. The toughening mechanisms were then proposed.

In this work, polydopamine (PDA) coated GO (PDA-c-GO) aerogels with different GO concentrations and GO/PDA ratios were prepared through the solution compounding and subsequent freeze-drying technologies. Microstructures and morphologies of these aerogels were comparatively characterized. Subsequently, the structure stability in different solution conditions and adsorption properties toward organic dyes and solvents were investigated in details. The results show that the self-polymerized PDA can be homogenously coated on GO sheets with polymerization time longer than 3 h, and the surface morphologies are greatly influenced by the GO concentration and GO/PDA ratio. Higher GO concentration and GO/PDA ratio lead to better structure stability in water solutions. Furthermore, all the aerogels can keep stable in cyclohexane. The excellent adsorption ability toward Methylene blue (MB) is obtained for the PDA-c-GO aerogels, among which the aerogel of 1.0 mg/ml-2:1 exhibits the highest adsorbing amount (633 mg/g) and rate. Moreover, the good adsorbing selectivity and excellent adsorption ability for organic solvents are also obtained for the PDA-c-GO aerogels. In general, the PDA-c-GO aerogels with excellent adsorption properties are successfully prepared and they possibly have a great application potential in the field of waste water treatment.

The incorporation of CNTs into the immiscible blends are increasingly attractive because of high performance, its wide application and great prospects for development in the future. The objective of this review focuses on CNTs toughened immiscible polymer blends based on the selective localization of CNTs in the immiscible blends. Firstly, the thermodynamic and kinetic factors that determines the localization of CNTs are introduced. The former is relative to the wetting coefficient that can be applied to evaluate the favorable polymer component for CNTs; and the latter relates to the migration of CNTs in polymer blends. Combined with the morphology evolution accompanying with the incorporation of CNTs, the selective localization of CNTs can be distributed in dispersed phase, continuous phase or at the interface, exhibiting different unique properties. Among these properties, CNTs toughened the immiscible polymer blends can be found in these two cases: CNTs disperse in one phase (droplets or continuous) or CNTs disperse at the interface. With the presence of CNTs in immiscible blend, the toughening mechanisms involve: 1) the formation of percolative CNTs network; 2) formation of “cross-linked”-like structure; 3) morphology evolution; 4) compatibilization of immiscible blends; 5) nanobridge effect of CNTs at the interface. This review details recent works for the above mentioned selective localization of CNTs in immiscible blend and corresponding the toughening mechanisms of CNTs for immiscible blends, which is proposed to provide a guidance for the polymer toughening.

As one of the typical polymorphic polymers, poly( l -lactide) (PLLA) exhibits great dependences of physical/chemical performances on the crystalline structures. In this work, the dependences of hydrolytic degradation behavior of PLLA on the crystal form (α′- and α-form, respectively) and crystallinity (lower than 30 wt% and higher than 45%, respectively) during the hydrolysis process were investigated for the first time. To endow the samples with different crystal forms and crystallinities, the amorphous PLLA samples were annealed under different conditions. The crystalline structures of the samples were investigated through various characterization methods. The hydrolytic degradation measurements were carried out at 50 °C in distilled water. Specifically, the degree of the hydrolytic degradation of samples was qualitatively analyzed through detecting the concentration of hydrolysate in the medium using UV–Vis spectroscope. The results showed that for the samples with relatively low crystallinity ( 45%), sample with α′-form exhibits more serious hydrolysis during the whole degradation process. The microstructure evolution of samples was also measured and the results showed that the crystalline structure evolution of the PLLA samples was mainly determined by the initial crystal structures of samples before hydrolytic degradation.

In this work, polypyrrole (PPy) particles were first decorated on the surface of graphene oxide (GO), then the hybrid PPy@GO particles were incorporated into poly(vinylidene fluoride) (PVDF) to prepare the PVDF/PPy@GO composites. The microstructure characterizations showed that PPy particles were successfully decorated on the GO platelets and simultaneously, GO was partially reduced. With the aid of GO, PPy particles with much smaller diameters exhibited good dispersion in the PVDF/PPy@GO composites. Interestingly, different from the apparent nucleation effect of PPy particles on PVDF crystallization, the nucleation effect of PPy particles in the PVDF/PPy@GO composites was greatly reduced. The PVDF/PPy@GO composites exhibited higher electrical conductivity compared with the PVDF/PPy composites. More interestingly, compared with the PVDF/PPy composites, largely enhanced permittivity and slightly reduced dielectric loss were simultaneously achieved for the PVDF/PPy@GO composites. The mechanisms were related to the construction of multiple-interfacial polarization and the enhanced conductivity of the composites.

Polycarbonate/poly(butylene terephthalate) (PC/PBT) blends exhibit wide applications in many fields. However, the blends usually exhibit poor mechanical and thermal properties because of the transesterification reaction occurred between molecules of the blend components. In this work, a small quantity of carbon nanotubes (CNTs) was introduced into the PC/PBT blend to prepare the ternary blend composites with balanced macroscopic properties. The dispersion of CNTs in the blend composites and the microstructural changes induced by CNTs were comparatively investigated. The results demonstrated that CNTs exhibit relatively homogeneous dispersion in the blend composites. Specifically, at relatively high content, CNTs form the percolated network structure. The crystallization ability of the PBT component is greatly enhanced with the aid of the nucleation effect of CNTs. Mechanical property measurements showed that CNTs exhibit strengthening and toughening effects on the PC/PBT blend, especially incorporating 2 wt% CNTs leads to the dramatic increase of tensile ductility. Further results showed that the blend composites also exhibit excellent antistatic performance. It is believed that the simultaneously improved fracture toughness and antistatic performance endow the blend composites with more potential applications.

Water-actuated shape memory polymers (SMPs) have great potential applications in many fields. Although many strategies have been developed to endow polymers with water-active shape memory effect (SME), so far it is still challenging to prepare the water-actuated SMPs with a highly sensitive SME in a method as facile as possible. In this work, poly(vinyl alcohol) (PVA) was incorporated into poly(ethylene vinyl acetate) (EVA) through the simple solution compounding processing. The blends exhibited good interfacial interaction on one hand. On the other hand, PVA exhibited excellent reinforcement effect, leading to the great enhancement of modulus and strength. Further results showed that the samples had excellent water uptake and dehydration abilities, and the presence of water resulted in the dramatic decrease of modulus and large increase of tensile ductility, which endowed the materials with great potential to realize complicated deformation at gentle force. The water-active SME was evaluated through cycling measurements, i.e. wetting-stretching-drying processes. The results showed that the water-active SME of the blends was greatly dependent upon the blend compositions. After several cycling measurements, the water-active SME of samples became stable. Specifically, for the sample containing 35 wt% PVA, the shape fixity and shape recovery ratios were increased up to 98.7% and 99.5%, respectively. The mechanisms for the excellent water-active SME were then discussed.

In this work, simultaneously enhanced thermal conductivity, heat dissipation and dielectric constant of poly(vinylidene fluoride) (PVDF) were prepared by adding ionic liquid (IL)-coated carbon nanotubes (IL@CNTs). IL@CNTs and common CNTs were melt-compounded with PVDF to prepare the composites, respectively. The results clearly demonstrated that IL@CNTs exhibited better dispersion and higher ability to form the percolated network structure. Studying on crystallization behaviors showed that IL@CNTs not only exhibited better nucleation effect on PVDF crystallization but also induced a large number of the polar β/γ-form crystallites formation in the composites. Thermal properties measurements showed that IL@CNTs exhibited more apparent role in enhancing the thermal conductivity of the composites. Specifically, IL@CNT endowed the composite sample with higher heat dissipation ability compared with the common CNTs during the cooling process. In addition, the largely enhanced dielectric constant was also achieved for the PVDF/IL@CNT composites. The mechanisms were analyzed and suggested to be mainly related to the improved dispersion and denser percolated network structure of IL@CNTs in the composites, the improved interfacial interaction between fillers and matrix, and the varied crystalline structure of the PVDF matrix. The prepared composites have great potential application as the heat management material of the flexible electronic devices.

Fabricating the thermally conductive composites through incorporating fillers into polymer matrix is usually at the sacrifice of the fracture toughness. To resolve such contradiction, this work proposed a feasible but highly efficient method of constructing the thermally conductive path in the epoxy composite at extremely low filler content. The polyvinylpyrrolidone (PVP) modified carbon nanofibers (P-CNFs) were coated on the three-dimensional (3D) framework surface of the melamine foam (MF), then the epoxy resin was impregnated into the MF@P–CNF. The results showed that the assembled structure of MF@P-CNFs could be well reserved in the epoxy composite. Consequently, at extremely low P–CNF content (0.8 wt%), the MF@P–CNF/EP sample shows the largely enhanced thermal conductivity (0.4 W/m·K) and glass transition temperature (167 °C) compared with the pure epoxy sample (0.2 W/m·K and 162 °C). Specifically, the composite sample also shows the apparently enhanced fracture toughness. Therefore, it is believed that coating CNFs on the 3D interconnected framework of MF is a promising way to prepare the epoxy composites with good comprehensive properties.

A flexible water-borne polyurethane (WPU)/MXene aerogel was applied as a supporting scaffold to confine polyethylene glycol (PEG) to fabricate photo-driven and flexible phase change material (PCM) composites. Firstly, the WPU@MXene aerogels with superior resilience were prepared via directional freeze-drying method. Secondly, the porous WPU@MXene aerogels were encapsulated with PEG by vacuum impregnation. The obtained WPU@MXene/PEG PCM composites possessed excellent dimension retention (98%@70 °C) along with high phase change enthalpy value (154.6 J g -1 ). Thanks to the three-dimensional interconnected structure and excellent photo absorption ability of MXene , the PCM composites showed superior solar-thermal energy conversion and storage capability. Additionally, combining the elasticity of the WPU@MXene aerogels and the solid-liquid phase change of PEG ensured that the PCM composites realized excellent light-actuated shape memory and self-healing functions. This study enriches the way for developing flexible and multifunctional PCM composites, as well as shows enormous potential applications for the efficient utilization of solar energy.

Biodegradable poly(L-lactic acid) (PLLA) based blend composites with excellent toughness exhibit comprehensive applications and they can be substitute for the common polyolefin and polyester based composites. To date, various strategies have been developed to enhance the toughness of the PLLA based blends or composites. Here, carbon nanofibers (CNFs) incorporated PLLA/poly(butylene adipate-co-butylene terephthalate) (PBAT) blend composites were investigated. The crystallinity of the PLLA matrix were precisely tailored through annealing treatment. Interestingly, CNFs and PBAT particles self-assembled into the “mutton kebab”-like structure during processing. In addition, the annealing treatment facilitated the epitaxial crystallization of PLLA on the surface of CNFs that were not covered by PBAT due to the excellent heterogeneous nucleation effect of CNFs. Consequently, with the addition of 1 wt% CNFs and tailoring the blend composite with the PLLA crystallinity of about 32.6%, the impact strength of the composite was increased by 270% from 10.0 kJ/m2 to 37.0 kJ/m2. The toughening mechanisms were mainly connected with the greatly strengthened interfacial interaction between PLLA matrix and PBAT particles by CNFs through CNFs bridging effect and CNFs inducing PLLA crystallization, facilitating the transfer of stress under the load condition, especially at high PLLA crystallinity. Furthermore, it was found that CNFs exhibited outstanding photothermal conversion effect, which could endow the blend composites with mechanical-damage-healing ability. This work not only reveals the role of crystalline structure in toughening of the PLLA-based blend composites but also paves an effective way to prepare super-toughened, biodegradable, heat resistant and mechanical-damage-healing PLLA-based composites via tailoring the crystalline structure of the matrix.

The wide application of the biodegradable polymers is the developing direction of the next generation microelectronic devices and electronic packaging because it can greatly reduce the risk of plastic pollution. However, most of biodegradable polymers have low thermal conductivity and low heat resistance. Synchronously improving the thermal conductivity and heat resistance of the biodegradable polymers without sacrificing the other performances is still great challenging. In this work, a novel method was proposed to highly efficiently improve the thermal properties of the poly( l -lactic acid) (PLLA) composites. To achieve this goal, hydroxylated graphene nanoplatelets were obtained by wet ball milling technology, and then ring-opening polymerization of lactide was initiated, and poly( d -lactic acid) (PDLA) and PLLA molecular chains were grafted on the hydroxylated graphene nanoplatelets to obtain the PDLA-graft-graphene nanoplatelets (G-g-PDLA) and PLLA-graft-graphene nanoplatelets (G-g-PLLA), respectively. Finally, the PLLA/G-g-PDLA and PLLA/G-g-PLLA composites were fabricated through melt compounding processing. The results showed that the PDLA molecular chains on the graphene nanoplatelets promoted the formation of the stereocomplex crystallites at the interface. Compared with the pure PLLA and PLLA/G-g-PLLA composites, the PLLA/G-g-PDLA composites exhibited higher thermal conductivity, largely enhanced heat distortion temperature, and better mechanical properties at high environmental temperature. For example, at G-g-PDLA content of 5 wt %, the composite sample showed the thermal conductivity of 1.12 W m−1K−1 and heat distortion temperature of 200 °C, which were 387 % and 65 °C higher than those of the pure PLLA, respectively. Morphological and microstructural characterizations were carried out and the mechanisms based on SCs formation at the interface were proposed. This work lights up the route for the application of the PLLA in the next generation microelectronic devices.

Interfacial polarization between fillers and polymer matrix in polymer composites would be responsible for enhancement of dielectric constant ( e ˊ ), but the dielectric mismatch between fillers and polymer also leads to an undesirable electric breakdown. Herein, we successfully developed a core-shell structured barium titanate@silver (BaTiO3 @Ag, BT@Ag) novel heterogeneous fiber via coaxial electrospinning followed by calcination technology, to simultaneously improve the dielectric property and breakdown strength ( E b ) of poly(vinylidene fluoride) (PVDF)-based composites. Dielectric measurement reveals that PVDF/BT@Ag composites have an enhanced e ˊ , low dielectric loss (tan δ) and moderately increased E b . Since the core-shell structured fibers help in tailoring the local electric field around the interface, but also provide double interfacial polarization, which effectively improves the dielectric properties of the composites. When the loading of BT@Ag reached up to 10 wt%, the e ˊ increased to 19.4 @1 kHz while the E b had maximum value of 389.1 MV/m, finally resulting in an improvement of U e . Moreover, the incorporation of BT@Ag obviously improves the mechanical properties of composites. It is expected that these results would further inspire the design of fillers with novel architecture for high-performance dielectric polymer composites.

As a renewable and environmentally friendly polymer, poly(L-lactic acid) (PLLA) has immense feasibility to replace traditional thermoplastics. However, the present application of PLLA as an engineering plastic in microelectronic devices still faces some obstacles, such as poor heat resistance and low thermal conductivity. In the present work, a facile solution compounding processing was employed to comprise poly(D-lactic acid) (PDLA) and carbon nanofibers (CNFs) into PLLA composites. Microstructure characterizations showed that the presence of PDLA not only induced a large amount of stereocomplex crystallites (SCs) but also promoted denser CNF network in the composites. Consequently, in contrast to the PLLA/CNF samples, the PLLA/PDLA/CNF samples showed largely promoted heat resistance and thermal conductivity. At 50 wt% PDLA and 20 wt% CNFs, the sample showed the heat resistant temperature (HRT) of 196.7 °C, about 56.7 °C greater than that of the PLLA/CNF (20 wt%), and the thermal conductivity of 2.34 Wm-1K−1, 1014% greater than that of the PLLA. The mechanisms were largely ascribed to the SCs formation, which promoted the stacking of CNFs to a certain extent. Specifically, SCs organized into a compact physical network at relatively high PDLA content, which exhibited a ‘locking’ effect on dispersion of CNFs, leading to the efficient lap of thermally conductive filler in the composites. This work indicates that in-situ forming SCs is a promising strategy for regulating the filler’s thermal conductive network in PLLA-based polymer, and the composites may be alternative engineering plastics of the future.

Structural relaxation of polymer chains exhibits high correlation to the macroscopic performance of polymers, and it has been well investigated and analyzed in the polymer systems. However, it is still challenging to accurately describe the structural relaxation of some complex systems, such as the nanomaterials incorporated blends. In this work, structural relaxations in the poly (vinylidene fluoride)/poly (methyl methacrylate) (PVDF/PMMA) blends in the presence of graphene oxide (GO) were systematically investigated via revealing the cooperativity concerning about segmental relaxation, chain relaxation relating to the crystallization behaviors using the broadband dielectric spectroscopy (DRS). In the presence of GO, the cooperative volume was enlarged and dynamic heterogeneity was weakened. And the chain relaxation α c moved to higher frequency; while the α m relaxation associated with molecular motion in miscible amorphous region of PVDF/PMMA blends can be well resolved. Thus, the structure relaxations confirmed that GO could hinder the crystallization of PVDF but enhance the miscibility in the PVDF/PMMA amorphous phase. On the basis of structure relaxations, the dielectric properties as function of temperature and frequency were accordingly studied, and at room temperature PVDF/PMMA blends in the presence of GO exhibited higher constant and lower loss at low frequency regions.

Due to the integrated development of electronic products, developing thermal management materials with excellent heat dissipation performance is still in challenging. In addition, in order to help the increasingly complex electronic devices to achieve better thermal management, the correspondingly efficient multi-directional heat dissipation materials are also needed. Presented here is a simple freezing device with a conical concave surface, which can successfully and effectively guide the growth of lamellar crystal into circinate vane type (CVT) network. The coaxial lamellae in CVT network provide an effective way for multi-directional heat dissipation in epoxy/CVT-BNNS (boron nitride nanosheets) composites. The axial thermal conductivities of the composite (11 vol% BNNS loading) measured along vertical and lateral direction are 2.53 and 2.40 W m −1 K−1, respectively. Compared with the composites with random network and uniaxial network, the composites with CVT network have more uniform and effective heat dissipation effect in 3D space.

The phase behaviors involving the phase fluctuation in melt of poly(vinylidene fluoride) (PVDF)/poly(methyl methacrylate) (PMMA) blends with varying graphite oxide concentration were investigated through dynamic rheological measurement. The phase diagrams of the blends with different concentration of graphite oxide were achieved through dynamic temperature and frequency sweep, showing the incorporation of graphite oxide would shift up the phase diagram of PVDF/PMMA blends and enlarge the miscibility window of the blends. Dynamic time sweep was applied to track the phase separation process, which exhibited that graphite oxide can slow down the phase separation process. The underlying mechanism for graphite oxide-driven miscibility in PVDF/PMMA blends was explored via evaluating the molecular entanglement of PVDF/PMMA/Graphite Oxide ternary composites. The interfacial tensions showed the selective adsorption of PMMA on graphite oxide, which was responsible for the role of graphite oxide as entanglement points. And it was found the increase of graphite oxide concentration could lead to higher entanglement density. Therefore, it can be concluded that the graphite oxide can act as entanglement point, further to stabilize the phase structure and to slow down the phase separation. This work serves as an experimental verification to enrich the thermodynamic and kinetic investigations on phase behaviors of particle-filled miscible blends; furthermore new insights are produced and provided to tailor the phase morphology of miscible blends via incorporation of particles.

In this work, carbon nanotubes (CNTs) were introduced into miscible poly(l-lactide)/poly(vinyl acetate) (PLLA/PVAc) blend and the crystallization behaviors of PLLA with the presence of PVAc and CNTs are systematically discussed. The dispersion state of CNTs was characterized using scanning electron microscope, and the crystallization behaviors of PLLA in different conditions including melt crystallization and cold crystallization were comparatively investigated using polarized optical microscope, differential scanning calorimetry and wide angle X-ray diffraction. The results showed that the crystallization of PLLA was greatly restricted by PVAc. CNTs exhibit apparent nucleation effect, promoting the occurrence of both melt crystallization and cold crystallization. However, the nucleation effect of CNTs in the ternary composites is weakened as compared with that in the binary PLLA/CNTs composites. It was suggested that the relatively higher interfacial affinity between PVAc and CNTs, which possibly resulted in more PVAc molecule rather than PLLA molecule around the surface of CNTs, was the main reason for the reduced nucleation efficiency.

In this work, polystyrene-grafted reduced graphene oxides (rGO-PS) were prepared via the emulsion polymerization with reserving the two-dimensional layer-like structure of graphene. TGA, FTIR, Raman results show that the amounts of polystyrene (PS) grafted on rGO from low to medium, high values can be tuned via incorporating different content of styrene in the PS polymerization recipe. Subsequently a series of PS-based composites containing different loading of rGO with variant amount of PS grafted on rGO were prepared. The effects of grafting amount on the resulting dielectric properties were carefully investigated. Compared with the composites containing rGO without any treatment, significantly increased dielectric constant and lower dielectric loss are observed for the composites with rGO-PS. Moreover, with increasing the amounts of grafted PS on rGO, the dielectric constants exhibit an increasing trend whereas the dielectric loss keeps at a stable level. For instance, when the loading of filler is fixed at 5 wt%, the composites containing rGOs with highest amount of grafted PS exhibit a maximum of dielectric constant 394.6@100 Hz, which is over 20 times larger than that of composites containing rGO. However, a relatively low dielectric loss tangent 0.45@100 Hz and conductivity 4.04 × 10 −9 S/cm@100 Hz are observed in the composites containing rGOs with highest amount of grafted PS, which is even lower than that of composites containing rGO. The improved interfacial polarization induced by the constructed PS layer between rGO and PS matrix is invoked to be responsible for the improved dielectric constant; on the other hand, the PS layer can restrict the conduction loss and suppress the dielectric loss. This work indicates that the dielectric performance of composites could be effectively ameliorated through the strategy of reasonably designing the interface structure of conductive fillers.

Degradable polyesters exhibit wide application in many fields due to the fact that the waste of these polymers can be easily reclaimed, which greatly reduces the environmental risk. In this work, a small quantity of water-soluble poly(ethylene oxide) (PEO) was introduced into biodegradable poly(butylene succinate) (PBS). Crystallization behavior of the PBS matrix was comparatively investigated using polarized optical microscope (POM), differential scanning calorimetry (DSC) and wide angle X-ray diffraction (WAXD). The results demonstrate that PEO affects the crystallization behavior of the PBS matrix, which is greatly dependent upon the PEO content. At relatively low PEO content, accelerated crystallization is achieved for the PBS matrix, while the role of PEO becomes inconspicuous at relatively high PEO content. The sample surface hydrophilicity was evaluated through contact angle measurement of distilled water. The results demonstrate that incorporating PEO into PBS greatly enhances the hydrophilicity of the sample surface. The hydrolytic degradation measurements were carried out under an alkaline condition. The results clearly show that the presence of PEO accelerates the hydrolytic degradation of the PBS matrix. Furthermore, the sample obeys the surface erosion mechanism. The mechanism for the largely enhanced hydrolytic degradation ability is then analyzed.

A small quantity of organic montmorillonite (OMMT) was introduced into an immiscible poly( l -lactide)/poly(ethylene vinyl acetate) (PLLA/EVA) blend. The selective location state of OMMT, the blend morphologies and the microstructure of the blend composites were systematically investigated. The theoretical calculation based on interfacial tensions and experimental observations showed that OMMT selectively located in the rigid PLLA component. Apparent morphological changes were observed for the blend composites. Rheological measurements showed that OMMT at relatively high content formed the percolated network structure in the blend composites. Tensile measurements showed that OMMT exhibited excellent reinforcement effect for the immiscible PLLA/EVA blends. Furthermore, tensile creep behavior measurements showed that incorporating OMMT into the immiscible PLLA/EVA blends facilitated the apparent enhancement of creep stability. The microstructure-performance relationship of the blend composites was then analyzed.

In this work, we developed a green synthesis method to prepare the hybrid aerogels containing graphene oxide (GO) and microcrystalline cellulose (MCC) using lithium bromide (LiBr) aqueous solution as the solvent, which insured the complete dissolution of MCC. The interaction between GO and MCC was investigated through different methods The results demonstrate that there is a strong interaction between GO and MCC molecules, which promotes the exfoliation of GO in the hybrid aerogels. The hybrid GO/MCC aerogels exhibit typical three dimensional porous structure and the pore morphology can be well adjusted by changing the content of GO. The adsorption ability of the hybrid aerogels was measured using methylene blue (MB) as an adsorbate. The results show that the adsorption ability of GO per unit mass is greatly enhanced compared with the pure GO aerogel, especially at relatively low GO content the adsorption amount of GO per unit mass is enhanced up to 2630 mg/g. Further results demonstrate that the hybrid GO/MCC aerogels still obey the pseudo-second-order adsorption model, which is similar to that of the pure GO aerogel. The mechanism for the amplified adsorption ability of GO in the hybrid GO/MCC aerogels is then analyzed.

A small quantity of graphene platelets (GNPs) were introduced into polystyrene (PS) to prepare the PS/GNP composites through one-step process (solution compounding, PS/GNP-S) and two-step process (solution compounding and subsequent melt compounding, PS/GNP-SM). The dispersion states and microstructures of GNPs in the composites were comparatively investigated. The results demonstrated that the PS/GNP-S composites exhibited relatively poor dispersion of GNP particles but relatively high ability to form the percolated GNP network compared with the PS/GNP-SM composites. Apparently increased glass transition temperatures were achieved for the PS/GNP-S samples. Conductive properties measurements showed that the PS/GNP-S samples exhibited relatively low volume resistivity. Largely enhanced thermal conductivity was achieved for the PS/GNP-S samples, and the thermal conductivity exhibited nonlinear behavior with increasing GNP content, which was different from the linear behavior of the PS/GNP-SM samples. The conductive mechanisms of the composites were discussed using two different analytic models.

In this work, multiwall carbon nanotubes (MWCNTs) were melt compounded with a poly(ethylene vinyl acetate)/thermoplastic polyurethane (EVA/TPU) blend to prepare EVA/TPU/MWCNT blend nanocomposites. The effects of the blend morphology and selective localization of MWCNTs on the dielectric properties including dielectric constant and loss were systematically investigated. The results show that when the blend exhibits sea–island morphology accompanying MWCNT selective localization in island droplets, the dielectric constant was increased to 1200@100 Hz with addition of 5 wt % MWCNTs; in addition, the growth of dielectric loss is suppressed and the values of dielectric loss always remain around 1 with varying the loading of MWCNTs. Furthermore, based on the investigations of rheological percolation testing, morphological observation, and selective localization, the microcapacitor model was evoked to explain the underlying mechanism for the improvement of the dielectric constant for the blend with sea–island mo...