Rational distribution and orientation of boron nitride nanosheets (BNNSs) are very significant for a polymer/BNNS composite to obtain a high thermal conductivity at low filler content. In this paper, a high-performance thermal interface material based on exfoliated BNNSs and polystyrene (PS) microspheres was fabricated by latex blending and subsequent compression molding. In this case, BNNSs and PS microspheres first self-assembled to form the complex microspheres via strong electrostatic interactions between them. The as-prepared complex microspheres were further hot-pressed around the glass transition temperature, which brought the selective distribution of BNNSs at the interface of the deformed PS microspheres. As a consequence, a polymer composite with homogeneous dispersion and high in-plane orientation of BNNSs in PS matrix was obtained. Benefitted from this unique structure, the resultant composite exhibits a significant thermal conductivity enhancement of 8.0 W m K at a low filler content of 13.4 vol %. This facile method provides a new strategy to design and fabricate highly thermally conductive composites.

Graphene-based heat-spreading films have captured high attention in academic study and commercial applications because of their extremely high thermal conductivity and desired flexibility. However, the electrical conductivity limits their utilizations in many electronic fields. Herein, to address this problem, fluorinated graphene (F-graphene) that is exfoliated from commercial fluorinated graphite was first used to prepare the flexible free-standing composite film via vacuum filtration of uniform poly­(vinyl alcohol)-assisted F-graphene suspension. The well-organized alignment of F-graphene lamellas makes the composite film show an ultrahigh in-plane thermal conductivity of 61.3 W m–1 K–1 at 93 wt % F-graphene. Despite at such high filler loading, the fabricated F-graphene film still possesses a superior electrical insulation property. Therefore, these results suggest that F-graphene, as the novel thermally conductive filler, demonstrates fascinating characters in the preparation of a thermally conductive yet electrically insulating nanocomposite.

Recently, graphene and carbon nanotubes (CNTs) promise considerable application potentials in the highly efficient thermal management of high-power devices because of their superb thermal conductivity (TC). However, the high electrical conductivity hampers their use in some fields where electrical insulating components are always required. Herein, to coordinate the thermal and electrical conductivity of CNT, fluorinated CNT (FCNT) was first used as a thermally conductive filler to prepare composite film with nanofibrillated celluloses (NFCs) via facile vacuum-assisted filtration. The obtained composite film shows a well-organized layered structure of the building blocks along the planar direction. Moreover, the one-dimensional structure of NFCs and the strong interaction of NFCs and FCNTs ensure sufficient connection between FCNT themselves and the reduced interfacial thermal resistance of NFCs/FCNTs, so that efficient heat transfer pathways can be well reserved, leading to simultaneous accessibility of high in-plane TC of 14.1 W m K and favorable electrical insulation property at an FCNT content of 35 wt %. Despite such a high FCNT loading, the strong interaction between NFCs and FCNTs enables the composite film to possess enhanced toughness, reliable mechanical strength, and flexibility. Therefore, we think that these outstanding comprehensive properties guarantee that the prepared composite film has promising applications in heat dissipation of next-generation portable and collapsible electronic devices.

Objectives: To explore the clinical therapeutic effects and safety of autologous bone marrow mesenchymal stem cell therapy for traumatic brain injury by lumbar puncture. Materials and Methods: A total of 97 patients (24 with persistent vegetative state and 73 with disturbance motor activity) who developed a complex cerebral lesion after traumatic brain injury received autologous bone marrow mesenchymal stem cell therapy voluntarily. The stem cells were isolated from the bone marrow of the patients and transplanted into the subarachnoid space by lumbar puncture. Results: Fourteen days after cell therapy, no serious complications or adverse events were reported. To a certain extent, 38 of 97 patients (39.2%) improved in the function of brain after transplant (P = .007). Eleven of 24 patients (45.8%) with persistent vegetative state showed posttherapeutic improvements in consciousness (P = .024). Twentyseven of 73 patients (37.0%) with a motor disorder began to show improvements in motor functions (P = .025). The age of patients and the time elapsed between injury and therapy had effects on the outcomes of the cellular therapy (P < .05). No correlation was found between the number of cell injections and improvements (P > .05). Conclusions:This study suggests that the bone marrow stem cell therapy is safe and effective on patients with traumatic brain injury complications, such as persistent vegetative state and motor disorder, through lumbar puncture. Young patients improve more easily than older ones. The earlier the cellular therapy begins in the subacute stage of traumatic brain injury, the better the results.