High Filler Loading Research Articles

Guayule Natural Rubber Latex and Bi2O3 Films for X-ray Attenuating Medical Gloves

Existing natural latex radiation-attenuating gloves (RAGs) contain a high loading of radiation attenuation filler that reduces their mechanical properties to below Food and Drug Administration (FDA) medical glove requirements. RAGs are commonly formulated using Hevea natural rubber latex and lead-based fillers. The former can cause life-threatening allergic responses and the latter are known for their toxicity. In this work, a new lead-free RAG formulation based on circumallergenic guayule natural rubber latex (GNRL) and non-toxic radiation attenuation filler bismuth trioxide (Bi2O3) was developed. GNRL films with Bi2O3 loadings ranging from 0 to 300 PHR at different thicknesses were prepared. Radiation attenuation efficiencies (AE) at 60, 80, 100, and 120 kVp were determined and attenuation isocontour curves predicted film thickness and Bi2O3 loading required to meet or exceed the radiation attenuation requirements of ASTM D7866 and commercial RAGs. Optimal curing conditions for GNRL/Bi2O3 films with 150 PHR Bi2O3 were investigated by varying curing temperatures and time from 87 °C to 96 °C and 65 min to 90 min, respectively. In general, as the loading of the filler increased, the density of the films increased while the thickness decreased. GNRL/Bi2O3 films with 150 PHR Bi2O3 and 0.27 mm provided 5% more AE than RAG market average attenuation at the same thickness. The films with 150 PHR Bi2O3 cured under near-optimal conditions (90 °C/85 min, and 87 °C/65 min) met both the radiation attenuation standard (ASTM D7866) and the natural latex surgeon and examination glove standards (ASTM D3577 and D3578, respectively). Thus, gloves made using our formulations and protocols demonstrated potential to meet and surpass medical natural latex glove standards, offer a single product for both infection control and radiation protection instead of double-gloving, provide a greater degree of comfort to the user, and simultaneously reduce contact reactions and eliminate potential latex allergic reaction.

Effect of thermal annealing and filler ball-milling on the properties of highly filled polylactic acid/pecan nutshell biocomposites

Biodegradable polymer composites reinforced with agri-food lignocellulosic biowaste represent cost-effective and sustainable materials potentially able to replace traditional composites for structural, household, and packaging applications. Herein, the preparation of polylactic acid (PLA)/pecan (Carya illinoinensis) nutshell (PNS) biocomposites at high filler loading (50 wt%) is reported, alongside the effect of two environmentally friendly physical treatments, namely ball-milling of the filler and thermal annealing on biocomposites.PNS enhanced the thermal stability, the viscoelastic response, and the crystallinity of the polymer. Furthermore, filler ball-milling also increased the melt fluidity of the biocomposites, potentially improving melt processing. Finally, the presence of PNS remarkably enhanced the effect of thermal annealing in the compounds. In particular, heat deflection temperature of the biocomposites dramatically increased, up to 60 °C with respect to the non-annealed samples. Overall, these results emphasize the potential of combining natural fillers and environmentally benign physical treatments to tailor the properties of PLA biocomposites, especially for those applications which require a stiff and lightweight material with low deformability.

Unique stiffness-deformability features of dendrimeric silica reinforced HDPE nanocomposites obtained by an innovative route

A set of dendrimeric silica (DS) reinforced polyethylene-based nanocomposites is prepared using a novel and straightforward in-situ catalyst supporting procedure by means of “ in-situ ” polymerization technique, labeled DS-SA. These materials are characterized with regard to molar masses, filler dispersion, thermal stability, crystalline characteristics, thermal properties and mechanical response and then compared with an equivalent set of samples prepared using a more common method, named DS-MAO, as well as a non-reinforced HDPE reference. The mechanical performance of all these materials is discussed based on the crystalline features and molar masses of the polymeric component together with the dispersion of the DS nanofiller. The results of this study confirm the potential of the DS-SA approach as an innovative and promising technique, with resulting materials achieving superior filler dispersion and significantly higher mechanical performance compared to their DS-MAO analogues at high filler loadings, while retaining the limit stretching ability of HDPE. • Polyethylene nanocomposites reinforced with dendrimeric silica particles are prepared. • An innovative approach inspired by an in-situ catalyst supporting concept is applied. • Dendrimer like silica particles are used as catalyst support and (nano)filler. • Crystallinity and filler dispersion are dependent on synthetic protocol used. • Hybrids reveal a superior mechanical response with excellent stiffness/deformability balance.

Thermally conductive hexagonal boron nitride/spherical aluminum oxide hybrid composites fabricated with epoxyorganosiloxane

Hexagonal boron nitrides (h-BNs) have received much attention as thermally conductive fillers because of their high thermal conductivity. However, their high aspect ratio hampers the realization of high filler loading by dramatically increasing viscosity and deteriorating the processability of the h-BN composites. To address this issue, an epoxyorganosiloxane with the viscosity of 250 mPa s was used to maximize h-BN loading in composites in this study. Although the BN-50 composite containing 50 wt% of h-BN achieved high in-plane thermal conductivity (5.25 W/m·K), its use was limited because of its low through-plane thermal conductivity (1.35 W/m·K) and high viscosity. To overcome this, spherical aluminum oxides (s-AOs) were incorporated into the h-BN composite with 40 wt% fillers. This increased the through-plane thermal conductivity of the h-BN/AO hybrid composites up to 2.47 W/m·K. Moreover, thanks to the spherical shape of AOs, the viscosity of the h-BN/AO hybrid composites was lower than that of the BN-50 composite despite higher filler loading.

Highly thermoconductive yet ultraflexible polymer composites with superior mechanical properties and autonomous self-healing functionality via a binary filler strategy.

It is still a formidable challenge to develop ideal thermal dissipation materials with simultaneous high thermal conductivity, excellent mechanical softness and toughness, and spontaneous self-healing. Herein, we report the introduction of sandwich-like boron nitride nanosheets-liquid metal binary fillers into an artificial poly(urea-urethane) elastomer to address the above issue, which confers the composite elastomer with a unique thermal-mechanical-healing combination, including a low modulus, high in-plane thermal conductivity and high mass loading of rigid fillers but self-recoverability and room-temperature self-healing.

Enhanced dielectric constant and suppressed electrical conductivity in polymer nanocomposite films via loading MXene/TiO2/MoS2 nanosheets

Conductor/polymer nanocomposites can achieve high dielectric constant with low filler loading, but conductive fillers come into contact with each other easily, resulting in the formation of conductive paths. In this work, MXene/TiO2/MoS2 nanosheets were prepared by one-step hydrothermal method, and MXene/TiO2/MoS2/poly(vinylidene fluoride-co-hexafluoropropylene) (P(VDF-HFP)) nanocomposite films were prepared by solution casting method. At 1 kHz, with an optimized MXene/TiO2/MoS2 nanosheets loading of 8.0 wt%, MXene/TiO2/MoS2/P(VDF-HFP) nanocomposite films achieve a high dielectric constant of 944 and maintain a low dielectric loss of 0.19. TiO2 and MoS2 semiconductive layers on the surface of MXene nanosheets can prevent the formation of conductive paths, and therefore, nanocomposite films possess suppressed electrical conductivity. Moreover, MXene/TiO2/MoS2 nanosheets can build more microcapacitor structures in nanocomposite films with higher filler loading, which further improves the dielectric constant of nanocomposite films. Finite element simulation shows that TiO2 and MoS2 semiconductive layers can lower the electric field intensity and polarization intensity at the interface between conductive fillers and polymer matrix. Herein, MXene/TiO2/MoS2/P(VDF-HFP) nanocomposite films possess not only excellent dielectric properties, but also excellent mechanical properties, which can be used as flexible dielectric materials in electronic packaging technology.

High performance membranes containing zeolitic imidazolate framework‐8 and polysulfone for CO2 removal from CH4

AbstractBACKGROUNDNatural gas is essential for the world's supply of energy due to its economic viability and environmental sustainability in producing adequate amounts of clean energy. However, the removal of CO2 as an undesirable impurity remains challenging in natural gas purification. In this work, high performance dense mixed matrix membranes (MMMs) containing a low loading (<2 wt%) of zeolitic imidazolate framework 8 (ZIF‐8) and polysulfone (PSF) were prepared via simple solvent evaporation method and single solvent for the removal of CO2 from CH4.RESULTSSignificant enhancements in CO2 permeability and CO2/CH4 ideal selectivity were obtained for the resultant MMMs as compared to the neat PSF membrane. The highest CO2 permeability of 33.57 Barrer and CO2/CH4 ideal selectivity of 39.03 were achieved for a PSF membrane loaded with 1 wt% of ZIF‐8; these values were 514% and 161% higher than those obtained for the neat PSF membrane, respectively. Furthermore, MMM embedded with 1 wt% of ZIF‐8 demonstrated CO2 plasticization pressure up to 16 bar, which is equivalent to an 100% increment of the value obtained for the neat PSF membrane.CONCLUSIONOverall, MMMs fabricated in this work demonstrated a significant improvement of CO2 separation from CH4 compared to the PSF‐based MMMs reported in the literature, where most of the reported MMMs contain high loading of fillers up to 30 wt%. Therefore, the MMMs fabricated in this work are ready to be further exploited for application in gas separation industries. © 2021 Society of Chemical Industry (SCI).

Mixed matrix membranes with highly dispersed MOF nanoparticles for improved gas separation

• IPD is used to modify ZIF-8 nanoparticles by a simple coordination interaction. • IPD@ZIF-8 nanoparticles exhibit excellent dispersity in various solvents. • H 2 /CH 4 selectivity of PI/IPD@ZIF-8 MMM with 45 wt% loading is increased by 46.6%. • The CO 2 plasticization resistance of PI/IPD@ZIF-8 MMMs is improved from 21 to 30 bar. Metal organic frameworks (MOFs) are ideal fillers for preparing mixed matrix membranes (MMMs) because of their molecular sieving property. However, MOF nanoparticles are not easy to be dispersed, which limits their application in MMMs with high MOFs loading. In this study, highly dispersed ZIF-8 nanoparticles with diameter of around 50 nm were prepared by coating isophthalic dihydrazide (IPD) molecular layer onto their surfaces via coordination interaction (abbre. IPD@ZIF-8). Benefiting from the highly stable and highly dispersed IPD@ZIF-8 solution, MMMs with high nanoparticles loading content and excellent uniformity are achieved. The modification of IPD on the surface of ZIF-8 nanoparticles greatly enhances the interfacial affinity between ZIF-8 as filler and 6FDA-Durene polyimide (PI) as polymer matrix under the interaction of strong hydrogen bond between them. Gas permeation results reveal that the H 2 permeability of IPD@ZIF-8 mixed PI (PI/IPD@ZIF-8) MMM with 45 wt% loading content is up to 8000 Barrer and the corresponding ideal selectivities of H 2 /CH 4 and H 2 /N 2 gas pairs are 15.1 and 13.0, which increase by 46.6% and 32.7%, respectively, comparing to those of ZIF-8 mixed PI (PI/ZIF-8) MMMs. The comprehensive separation performance of PI/IPD@ZIF-8 MMMs surpasses the 2008 Robeson’s upper bounds. The surface modification of IPD enhances the CO 2 plasticization resistance property of PI/IPD@ZIF-8 MMMs from 21 bar to 30 bar. This study provides a facile and easy-operated strategy for the surface modification of MOF nanoparticles, and opens up a new way for the preparation of MMMs with high filler loading and good quality.

Thermal insulation and mechanical characteristics of polyester filled with date seed wastes

In this study, the feasibility of utilizing date palm seeds (DS), the primary waste in date industry, as a filler in unsaturated polyester (UPR) matrix to develop thermal insulation material was investigated. Stable homogenous DS-UPR composites with up to 70 vol% natural filler were prepared at room temperature following a thermoset curing process. The developed composites were subjected to different physical, thermal, and mechanical tests. Moreover, the developed composites were characterized using different techniques (such as scanning electron microscopy (SEM), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and Fourier-transform infrared spectroscopy (FTIR)). Density and water retention measurements were verified using different theoretical models. FTIR analysis suggests the existence of hydrogen bonding between DS fibers and UPR, which was more pronounced at high filler loadings. Replacing till 50 vol% of UPR with DS produced composites that possess promising thermal insulation and construction properties with relatively low thermal conductivity (0.126 – 0.138 W/(m∙K)), low thermal diffusivity (0.109 – 0.096 mm2/s), low water retention (0.47–3.44%), and high compressive (38.4–88.0 MPa) and tensile strengths (9.4 – 35.1 MPa). Moreover, addition of date seeds to unsaturated polyester matrix slightly increased its glass transition temperature and improved its thermal stability. The novel DS-UPR developed composite can be used as an alternative insulation material because of its superior properties compared with those of the traditional thermal insulators.

Enhanced thermal conductivity of epoxy composites by constructing thermal conduction networks via adding hybrid alumina filler

AbstractHigh thermal conductivity of polymer composites could be achieved through constructing 3D continuous thermally conductive networks into polymer composites. Herein, we demonstrate a simple, effective method to optimize the segregated alumina networks by using ternary mixture of alumina particles with different diameter ratios (5.8 μm + 2.6 μm + 0.5 μm) at the fixed total content of 60 wt% via conventional melt blending method. The thermal properties of epoxy composites were investigated as a function of the weight fraction and particle size of alumina particles. The thermal conductivity (TC) values of composites with coarse fillers (13.2 μm) are in agreement with Agari model at high filler loading (57 ~ 67 wt%). And the value of C2 was ~0.949 (close to 1), indicating that the formation of heat conduction paths in the composites. The addition of 60 wt% smaller fillers (2.6 μm) facilitates a higher interaction degree between the polymer/fillers, consequently, leads to a higher Tg of 147.8°C. A high TC of 1.109 W m−1 K−1 is achieved as the ratio of alumina filler with different particle sizes is 7/2/1, corresponding to a TC enhancement of 23%–32% compared to the composites with a single particle size filler. A suitable proportion of hybrid fillers is crucial for constructing three‐dimension continuous network, in which nano‐particles filled between the micro‐particles could increase the particle‐to‐particle connectivity.

Amino-functionalized NUS-8 nanosheets as fillers in PIM-1 mixed matrix membranes for CO2 separations

Membrane-based separation technologies are promising for various applications such as carbon capture and storage (CCS). Herein, we report the preparation and performance of mixed matrix membranes (MMMs) for carbon dioxide (CO2) separation. The MMMs comprise amino-functionalized metal-organic framework (MOF) nanosheets (NUS-8-NH2) dispersed in the polymer of intrinsic microporosity 1 (PIM-1). Specifically, the MOF nanosheets were synthesized through a bottom-up method and introduced into the PIM-1 matrix to fabricate NUS-8-NH2/PIM-1 MMMs. The uniformly dispersed MOF nanosheets could afford additional fast transport pathways through intra-flake pores and inter-flake nano-channels. Moreover, the amino groups could enhance CO2 transport within NUS-8-NH2/PIM-1 MMMs. In addition, hydrogen bonding between the NUS-8-NH2 filler and PIM-1 matrix improved interfacial compatibility. Therefore, the as-prepared MMMs could achieve a high filler loading of 15 wt% without sacrificing separation performance. Compared with the pure PIM-1 membrane, the MMM with 10 wt% NUS-8-NH2 showed CO2 permeability of ∼14000 Barrer and a CO2/N2 selectivity of ∼30, surpassing the 2008 Robeson's upper bound.

Microcellular epoxy/graphene nanocomposites with outstanding electromagnetic interference shielding and mechanical performance by overcoming nanofiller loading/dispersion dichotomy

With the rapid evolvement of wireless communication technologies, the ever increasing needs to prevent electromagnetic waves (EMWs) pollution have urged the development of lightweight materials with excellent electromagnetic interference (EMI) shielding property. However, achieving desired EMI shielding performance often requires high loadings of conductive nanofillers, like graphene, which poses challenges to control the nanoparticle dispersion and the mechanical performance of the nanocomposite. Herein, we demonstrate a method to fabricate highly-loaded (>30 wt%) graphene in microcellular epoxy nanocomposites, successfully overcoming the long-lasting dichotomy in the field of nanocomposites of high filler loading and dispersion. By utilizing supercritical CO2 foaming method, modified thermosetting epoxy-based nanocomposite was foamed with multiple interfaces and tunable microcellular cells. In addition, a rearrangement of nanofillers during foaming process is favorable for more intense conductive network, leading to enhanced EMWs attenuation by repeated reflections and absorptions. An optimal combination of electrical conductivity (314 S m−1), EMI shielding effectiveness (86.6 dB and 156.3 dB/(g/cm3)), compressive strength (27.4 MPa) and density (0.55 g cm−3) has been achieved for foamed nanocomposite with 32.26 wt % graphene content. This versatile method opens up an easy route to fabricate lightweight structural foams with high nanofiller contents, which could be used in many applications such as electronics, robotics, and aircrafts.

Effective EMI shielding behaviour of thin graphene/PMMA nanolaminates in the THz range

The use of graphene in a form of discontinuous flakes in polymer composites limits the full exploitation of the unique properties of graphene, thus requiring high filler loadings for achieving- for example- satisfactory electrical and mechanical properties. Herein centimetre-scale CVD graphene/polymer nanolaminates have been produced by using an iterative ‘lift-off/float-on’ process and have been found to outperform, for the same graphene content, state-of-the-art flake-based graphene polymer composites in terms of mechanical reinforcement and electrical properties. Most importantly these thin laminate materials show a high electromagnetic interference (EMI) shielding effectiveness, reaching 60 dB for a small thickness of 33 μm, and an absolute EMI shielding effectiveness close to 3·105 dB cm2 g−1 which is amongst the highest values for synthetic, non-metallic materials produced to date.

Sealing Tröger base/ZIF-8 mixed matrix membranes defects for improved gas separation performance

Manufacturing defect-free mixed matrix membranes (MMMs) especially with high nanoparticle concentrations exceeding 40 wt% is still an ongoing challenge. Desired performance improvements are often unfulfilled in MMMs with high filler loading because nanoparticles with increasing contents are prone to aggregating, forming non-selective cavities, and deteriorating membrane's mechanical properties. To address this key issue, our work develops MMMs using Tröger base (TB) polymer with more hydrogen bond acceptors, polydopamine (PDA), and ZIF-8 fillers. The PDA modified ZIF-8 to create TB/ZIF-8 MMMs especially with high ZIF-8 loading over 40 wt% improves membrane mechanical properties and completely seals structural defectives to demonstrate encouraging gas selectivities. Hydrogen bonding between CN:NH and CN:OH groups within TB polymers and PDA enhances ZIF-8 interactions and reduces particle agglomeration within the polymer matrix. A TB/ZIF-8@PDA MMM containing 50 wt% ZIF-8 has H2 and CO2 permeabilities of 664.1 and 277.3 Barrer. Its ideal H2/CH4 and CO2/CH4 selectivities are 37.7 and 15.5, respectively. Equal molar CO2/CH4 mixed gas tests at various pressures demonstrate strong CO2 plasticization resistance and enhanced CO2/CH4 gas selectivity over ideal selectivity within the membranes. The combination of PDA modification technique on filler surfaces and a polymer with many hydrogen bonds acceptors is not only a feasible route to fabricate high filler loading MMMs with sealed defective structures, but also demonstrates positive impacts on membrane mechanical properties.

A novel method to incorporate functional filler into TPSiV for balanced physical properties

Various literatures have reported that incorporating functional fillers into thermoplastic vulcanizates (TPVs) is an ideal method to prepare functional TPVs with balanced properties. Nevertheless, it is quite difficult to achieve that for thermoplastic silicone vulcanizate (TPSiV) due to their rather high silicon rubber (SiR) content as well as delicate balance between processing ability and various physical properties. Herein, a novel method involves using CNT/TPU phase as polymer matrix to disperse TPSiV particles through solution processing is proposed. Compared with randomly dispersed CNTs and traditional segregated CNTs network with TPSiV particles, composites fabricated by such method illustrate much better balance between various properties, including: low percolation threshold (Pc), comprehensive mechanical performance, better electromagnetic interference (EMI) shielding ability, etc. CNT/TPU anchored TPSiV double-percolated composite illustrates comparable Pc (0.42 wt%) to traditional segregated TPSiV/CNT composite (0.38 wt%), while the TPSiV composite with randomly dispersed CNT shows apparently high Pc (1.37 wt%). More importantly, both tensile strength and elongation at break are improved for these compoistes with double-percolation structure. It is even better than neat TPSiV composites at the same CNT loading. The prepared two types of segregated composites demonstrate similar electrical conductivity at high filler loading (≥1 wt%), enabling them with similar EMI performance, but the one with CNT/TPU as adhesive phase is much more stable after 100 times bending, illustrating negligible attenuation. This study provides a novel approach for incorporating functional fillers into TPSiV matrix for balanced properties.

Ferromagnetic Ti3CNCl2-decorated RGO aerogel: From 3D interconnecting conductive network construction to ultra-broadband microwave absorber with thermal insulation property

It remains urgent challenges to adopt suitable strategies to consume unwanted microwave pollution emitted by high-tech electronic devices satisfactorily. Confronted with narrow effective absorption bandwidth (EAB) and high filler loading bottlenecks of MXene-Based microwave absorber, herein, we employ Lewis molten salt etching approach to both exfoliate Ti3AlCN powders into Ti3CNCl2 suspension and intercalate ferromagnetic composition into interlamination simultaneously. By utilizing the crosslinking effect of dopamine, the Ti3CNCl2 are anchored on the surfaces of graphene oxide (GO) nanosheets, constructing interconnecting microstructure. Both the 3D conductive network and the modification of MXene manifest crucial impacts on enhancing microwave absorption performance of the resulting ultra-lightweight reduced GO (RGO)-based aerogel. The minimum intensity of reflection loss achieves −62.62 dB with the absorber mass loading of 0.7 wt%. Remarkably, more than 90% of the incident microwave is qualified to be absorbed over the whole Ku band. The EAB is broadened while tailoring the thickness to 3 mm, ranging from 10.2 to 18 GHz. Besides, the aerogel presents valuable thermal insulation properties. Our methodology of synthesizing MXene/RGO aerogel not only provides promising insights into microstructural construction but also endows the possibility for integrating thermal insulation property towards next-generation high-performance microwave absorption devices.

Hybrid of multi‐dimensional fillers for thermally enhanced polyamide 12 composites fabricated by selective laser sintering

AbstractSelective laser sintering (SLS) is an additive manufacturing technology that can provide a novel strategy to manufacture complex polymer‐based composites with tailored properties. In this study, polyamide 12 (PA12) composite powders based on Al2O3, boron nitride (BN), and carbon nanotubes (CNTs) were prepared via a two‐step mixing approach. Morphology characterization techniques indicated that the fillers were uniformly dispersed in the PA12 matrix as expected. Under the optimum 3D‐printing parameters, the fabrication of SLS parts with high filler loading could be obtained. With 40 wt% Al2O3, 8 wt% BN, and 2 wt% CNT hybrid fillers, the thermal conductivity of PA12 composites could reach 1.09 W/mK. It could be attributed to the synergistic effect of multi‐dimensional fillers to form dense and continuous thermal conduction paths. The factors influencing the performance of PA12 composites such as melting and crystallization behaviors, dielectric properties, and mechanical properties were also discussed. The results show that these composites have favorable dielectric and mechanical properties. Overall, the PA12 composites fabricated by SLS technology in this study exhibit excellent thermal management ability.

Multilayered graphene/boron nitride/thermoplastic polyurethane composite films with high thermal conductivity, stretchability, and washability for adjustable-cooling smart clothes

Polymers having high filler loading levels are not able to meet the increasing requirements of thermal interface materials by themselves; therefore, fillers and structures with unique advantages have been developed. In this study, mechanical mixing was used to disperse graphene nanoplatelets (GNPs) and boron nitride (BN) fillers inside thermoplastic polyurethane (TPU)-based films, which were then compounded into a multilayered structure. The multilayered BN-GNP/TPU composite film created during this study exhibited a high thermal conductivity of 6.86 W m−1 K−1 at a low filler loading of 20 wt% BN with 20 wt% GNP, which was significantly higher (2844%) than that of the neat TPU film. The composite film also had good durability to flexural fatigue and laundering. This was exhibited by maintaining thermal conductivity values of 6.25 W m−1 K−1 after 5000 cycles of the flexural fatigue test, and 6.85 W m−1 K−1 after 10 cycles of laundering, respectively. Furthermore, enhanced thermal stability, cooling, and hydrophobic properties of the multilayered BN-GNP/TPU composite films were also observed with the resulting composite film. Overall, such a system provides a facile approach that is applicable for the fabrication of multifunctional materials as thermal interface materials within smart cooling garments.

Surface modified boron nitride towards enhanced thermal and mechanical performance of thermoplastic polyurethane composite

Owing to the unpredictable advancement in electronic devices, the demand for highly thermally conductive and electrically insulating material is increasing day by day. Besides, surface treatment of chemically inert hexagonal boron nitride (h-BN) sheets found challenging and a distressing contention towards its acceptable thermal transportation. Herein, h-BN sheets are functionalized with divergent amines (its three isomers) to obtain their astonishing properties like high disperse ability and development of interfacial conduction in polymer composite. This comparative study elucidates the significance of the covalent interaction of amines (-NH2) with h-BN lattice as well as strong hydrogen bonding with thermoplastic polyurethane (TPU) matrix. It is demonstrated that both ortho-phenylenediamine o-PDA-BN and para-phenylenediamine p-PDA-BN filled TPU composites exhibit higher through-plane thermal conductivity (┴TC) of 2.06 and 1.96 W m−1 K−1 respectively by substantially establishing a higher thermal transportation path at high filler loading of 45 wt %. Whereas, meta-phenylenediamine m-PDA-BN composites reveal somewhat low ┴TC of 1.27 W m−1 K−1 at the same filler loading. Interestingly, all fabricated composites consisting of functionalized BN (f-BN) and TPU show unprecedented thermal and mechanical properties at such a high filler loading which demonstrates their great potential for packaging application in microelectronics.

In-situ generation of polymer molecular sieves in polymer membranes for highly selective gas separation

Molecular sieve materials (MSMs) are regarded as ideal fillers for the fabrication of mixed matrix membranes (MMMs). However, the preparation of MSMs-based MMMs usually involves physical mixing of insoluble filler and polymer matrix, which inevitably leads to filler agglomeration and two-phase incompatibility especially for high filler loading. Herein, we report a new strategy to construct MMMs through generating polymer molecular sieve (PMS) fillers in-situ in a thermally stable polymer matrix by post heating treatment. The in-situ generated PMS-based MMMs (i-PMS MMMs) possess greatly improved interfacial compatibility between matrix and filler and the effective loading content of PMS filler can reach as high as 70 wt%. The molecular sieving property of PMS endows the i-PMS MMMs with high gas selectivity of 183.0 for H2/CH4 and 128.9 for H2/N2, approaching or exceeding the state-of-the-art 2015 upper bound.