Fabrication of Al2O3/ZnO and Al2O3/Cu Reinforced Silicone Rubber Composite Pads for Thermal Interface Materials.

Thermal interface materials (also known as thermal pads) are widely used as a crucial part to dissipate heat generated in miniaturized and integrated electronic components. Here, we systematically investigated the effects of small ceramic and metallic powders in rubbery thermal composite pads with a high content of aluminum oxide filler on the thermal conductivity of the composite pads. We optimized the compositions of aluminum oxide fillers with two different sizes in a polydimethylsiloxane (PDMS) matrix for rubbery composite pads with a high thermal conductivity. Based on the optimized compositions, zinc oxide powder or copper powder with an average size of 1 µm was used to replace 5 µm-sized aluminum oxide filler to examine the effects of the small ceramic and metallic powders, respectively, on the thermal conductivity of the composite pads. When zinc oxide powder was used as the replacement, the thermal conductivity of the rubbery composite pads decreased because more air bubbles were generated during the processing of the mixed paste with increased viscosity. On the other hand, when the copper powder was used as a replacement, a thermal conductivity of up to 2.466 W/m·K was achieved for the rubbery composite pads by optimizing the mixing composition. SEM images and EDS mapping confirmed that all fillers were evenly distributed in the rubbery composite pads.

Drug loading augmentation in polymeric nanoparticles using a coaxial turbulent jet mixer: Yong investigator perspective.

HYPOTHESIS: In conventional 'bulk' nanoprecipitation, the capacity to load hydrophobic drugs into the polymeric nanoparticles (NPs) is limited to about 1%. The size distribution of the resulting NPs becomes polydisperse when higher precursor concentration is used to increase the drug loading. Hence, it should be possible to enhance the hydrophobic drug loading in polymeric NPs while maintaining the uniform NP size distribution by optimizing the nanoprecipitation process and purification process. EXPERIMENTS: Systematic studies were performed to enhance the loading of docetaxel (Dtxl) by using a process of centrifugal spin-down, rapid mixing by turbulence, and addition of co-solvent. The size distributions and Dtxl loading of the NPs were measured using dynamic light scattering and HPLC, respectively. FINDINGS: The centrifugal spin-down process helps to maintain uniform size distribution even at the high precursor concentration. In bulk nanoprecipitation, the resulting NPs achieved Dtxl loading up to 3.2%. By adopting turbulence for rapid mixing, the loading of Dtxl increased to 4.4%. By adding hexane as co-solvent, the loading of Dtxl further increased to 5.5%. Because of the drug loading augmentation, high degree of control, and extremely high production rate, the developed method may be useful for industrial-scale production of personalized nanomedicines by nanoprecipitation.