Highly Exfoliated Boron Nitride Nanosheets via Carboxyl Nanocellulose for Thermally Conductive Nanocomposite Films

The continuous development of electronic devices toward high-power and integrated directions has led to an increasing demand for renewable polymer composite materials with high thermal conductivity and electrical insulation to solve the problem of overheating in electronic devices. Cellulose is inherently insulating, with insufficient thermal conductivity. Although boron nitride nanosheets (BNNSs) have excellent thermal conductivity, hexagonal boron nitride (h-BN) ligands in their raw state are prone to aggregation, which limits their performance. In this work, h-BN was first ball-milled and amino-modified, and then, carboxylated nanofibrillated cellulose (COOH-CNF) was used to disperse the BNNSs. With the help of amide bonding, the BNNSs were uniformly dispersed in the nanocellulose (CNF) matrix; this reduced the aggregation and the presence of voids between the BNNSs and promoted the construction of effective thermal channels. The resulting composite slurry was stably dispersed and could be filtered to form a film; the best overall performance was achieved for a BNNS loading of 30% with a thermal conductivity (TC) of 9.00 W·m–1·K–1 (pure CNF 1.88 W·m–1·K–1). In addition, the volume resistivity reached 9.38 × 1013 Ω·cm (pure CNF of 2.53 × 1013 Ω·cm) and the electrical strength reached 22.67 kV·mm (17.04 kV·mm for CNF). Our results showed that the BNNS-CNF composite film had high TC and excellent insulating properties; therefore, its application in the thermal management of electronic devices has broad application prospects

Tumor bodies of hairless mice after injection of JAR cancer cells infected with V-BCRPi and treatment with 5-FU.

<p>A1: Tumor body injected with PBS alone; A2: Tumor body injected with PBS and 5-FU; B1: Tumor body injected with V-BCRPi alone; and B2: Tumor body injected with V-BCRPi and 5-FU. After injecting 5-FU, the tumors in the hairless mice injected with V-BCRPi were smaller than those in the un-injected hairless mice. The anti-tumor rate was approximately a factor of 10 (<i>P</i><0.01). It was concluded that V-BCRPi increases the inhibition effects of 5-FU on tumor growth.</p

Residual drug volumes after infection of JAR cells with V-BCRPi according to flow cytometry analysis.

<p>The results of experimental groups 1 to 9 are shown: 1: mock cells, 2: cells with Mit, 3: cells with Mit and Ko143, or cells with Mit and infected with 4: V-BCRP1i, 5: V-BCRP2i, 6: V-BCRP3i, 7: V-BCRP1i-c, 8: V-BCRP2i-c, or 9: V-BCRP3i-c. Each residual drug volume represents the mean value of three independent experiments. *<i>P</i><0.01.</p