Mechanically and Thermally Guided, Honeycomb-like Nanocomposites with Strain-Insensitive High Thermal Conductivity for Stretchable Electronics

Thermal management materials have become increasingly crucial for stretchable electronic devices and systems. Drastically different from conventional thermally conductive materials, which are applied at static conditions, thermal management materials for stretchable electronics additionally require strain-insensitive thermal conductivity, as they generally undergo cyclic deformation. However, realizing such a property remains challenging mainly because conventional thermally conductive polymer composites generally lack a mechanically guided design. Here, we report a honeycomb-like nanocomposite with a three-dimensional (3D) thermally conductive network fabricated by an arrayed ice-templating technique followed by elastomer infiltration. The hexagonal honeycomb-like structure with thin, compact walls (≈ 40 μm) endows our composite with a high through-plane thermal conductivity (≈ 1.54 W m–1 K–1) at an ultralow boron nitride nanosheet (BNNS) loading (≈ 0.85 vol %), with an enhancement factor of thermal conductivity up to 820% and thermal-insensitive strain up to 200%, which are 2.7 and 2 times higher than those reported in the literature. We report an intelligent strategy for the development of advanced thermal management materials for high-performance stretchable electronics

Mechanically and Thermally Guided, Honeycomb-like Nanocomposites with Strain-Insensitive High Thermal Conductivity for Stretchable Electronics

Thermal management materials have become increasingly crucial for stretchable electronic devices and systems. Drastically different from conventional thermally conductive materials, which are applied at static conditions, thermal management materials for stretchable electronics additionally require strain-insensitive thermal conductivity, as they generally undergo cyclic deformation. However, realizing such a property remains challenging mainly because conventional thermally conductive polymer composites generally lack a mechanically guided design. Here, we report a honeycomb-like nanocomposite with a three-dimensional (3D) thermally conductive network fabricated by an arrayed ice-templating technique followed by elastomer infiltration. The hexagonal honeycomb-like structure with thin, compact walls (≈ 40 μm) endows our composite with a high through-plane thermal conductivity (≈ 1.54 W m–1 K–1) at an ultralow boron nitride nanosheet (BNNS) loading (≈ 0.85 vol %), with an enhancement factor of thermal conductivity up to 820% and thermal-insensitive strain up to 200%, which are 2.7 and 2 times higher than those reported in the literature. We report an intelligent strategy for the development of advanced thermal management materials for high-performance stretchable electronics

Mechanically and Thermally Guided, Honeycomb-like Nanocomposites with Strain-Insensitive High Thermal Conductivity for Stretchable Electronics

Thermal management materials have become increasingly crucial for stretchable electronic devices and systems. Drastically different from conventional thermally conductive materials, which are applied at static conditions, thermal management materials for stretchable electronics additionally require strain-insensitive thermal conductivity, as they generally undergo cyclic deformation. However, realizing such a property remains challenging mainly because conventional thermally conductive polymer composites generally lack a mechanically guided design. Here, we report a honeycomb-like nanocomposite with a three-dimensional (3D) thermally conductive network fabricated by an arrayed ice-templating technique followed by elastomer infiltration. The hexagonal honeycomb-like structure with thin, compact walls (≈ 40 μm) endows our composite with a high through-plane thermal conductivity (≈ 1.54 W m–1 K–1) at an ultralow boron nitride nanosheet (BNNS) loading (≈ 0.85 vol %), with an enhancement factor of thermal conductivity up to 820% and thermal-insensitive strain up to 200%, which are 2.7 and 2 times higher than those reported in the literature. We report an intelligent strategy for the development of advanced thermal management materials for high-performance stretchable electronics

Mechanically and Thermally Guided, Honeycomb-like Nanocomposites with Strain-Insensitive High Thermal Conductivity for Stretchable Electronics

Thermal management materials have become increasingly crucial for stretchable electronic devices and systems. Drastically different from conventional thermally conductive materials, which are applied at static conditions, thermal management materials for stretchable electronics additionally require strain-insensitive thermal conductivity, as they generally undergo cyclic deformation. However, realizing such a property remains challenging mainly because conventional thermally conductive polymer composites generally lack a mechanically guided design. Here, we report a honeycomb-like nanocomposite with a three-dimensional (3D) thermally conductive network fabricated by an arrayed ice-templating technique followed by elastomer infiltration. The hexagonal honeycomb-like structure with thin, compact walls (≈ 40 μm) endows our composite with a high through-plane thermal conductivity (≈ 1.54 W m–1 K–1) at an ultralow boron nitride nanosheet (BNNS) loading (≈ 0.85 vol %), with an enhancement factor of thermal conductivity up to 820% and thermal-insensitive strain up to 200%, which are 2.7 and 2 times higher than those reported in the literature. We report an intelligent strategy for the development of advanced thermal management materials for high-performance stretchable electronics

Thermoresponsive Composite Hydrogels with Aligned Macroporous Structure by Ice-Templated Assembly

Natural tissues, such as bone, tendon, and muscle, have well-defined hierarchical structures, which are crucial for their biological and mechanical functions. However, mimicking these structural features still remains a great challenge. In this study, we use ice-templated assembly and UV-initiated cryopolymerization to fabricate a novel kind of composite hydrogel which has both aligned macroporous structure at micrometer scale and a nacre-like layered structure at nanoscale. Such hydrogels are macroporous, are thermoresponsive, and exhibit excellent mechanical performance (they are tough and highly stretchable), attractive properties that have a significant impact on the wide applications of composite hydrogels, especially as tissue-engineering scaffolds. The fabrication method in this study including freeze-casting and cryopolymerization can also be applied to other materials, which makes it promising for designing and developing smart and multifunctional composite hydrogels with hierarchical structures

Isotropically Ultrahigh Thermal Conductive Polymer Composites by Assembling Anisotropic Boron Nitride Nanosheets into a Biaxially Oriented Network

The demand for thermally conductive but electrically insulating materials has increased greatly in advanced electronic packaging. To this end, polymer-based composites filled with boron nitride (BN) nanosheets have been intensively studied as thermal interface material (TIM). However, it remains a great challenge to achieve isotropically ultrahigh thermal conductivity in BN/polymer composites due to the inherent thermal property anisotropy of BN nanosheets and/or the insufficient construction of the 3D thermal conductive network. Herein, we present a high-performance BN/polymer composite with a biaxially oriented thermal conductive network by a dendritic ice template. The composite exhibits both ultrahigh in-plane (∼39.0 W m–1 K–1) and through-plane thermal conductivity (∼11.5 W m–1 K–1) at 80 vol % BN loading, largely exceeding those of reported BN/polymer composites. In addition, our composite as a TIM shows higher cooling efficiency than that of commercial TIM with up to 15 °C reduction of the chip temperature and retains good thermal stability even after 1000 heating/cooling cycles. Our strategy represents an effective approach for developing advanced thermal interface materials, which are greatly demanded for advanced electronics and emerging areas like wearable electronics

Influence of wastewater sludge properties on the performance of electro-osmosis dewatering

<p>Although the properties of municipal wastewater sludge play key roles in the electro-osmosis dewatering process, it is still controversial which properties have the greatest effect on the dewatering performance. In this study, multiple regression models with the Group Lasso method were used to investigate the relationship between the final moisture content and the sludge properties, including pH, electrical conductivity (EC), volatile solids content, zeta potential (<i>ζ</i>), initial moisture content, extracellular polymeric substances (EPS), proteins of EPS (EPSPr), polysaccharides of EPS (EPSPo) and the ratio of EPSPr and EPSPo (EPSR). Under the optimal conditions (pressure = 100 kPa, voltage = 50 V and cake thickness = 15 mm), EPS, EC and <i>ζ</i> were significantly related to sludge dewaterability and EPS was the most important factor. Furthermore, the coefficient estimate of EPSPo was greater than that of EPSPr and the coefficient of EPSR was negative, indicating that EPSPo plays more important roles in electro-osmosis dewatering than EPSPr. Thus, reducing the EPS content of sludge, especially the EPSPo content, is necessary to improve the performance of electro-osmosis dewatering.</p

Data_Sheet_1_Association of the oxidative balance score with obesity and body composition among young and middle-aged adults.docx

ObjectiveThe oxidative balance score (OBS) is important for determining the cause of obesity and its complications. We aimed to evaluate the association between OBS and obesity and other segmental body composition parameters among young and middle-aged U.S. adults.Methods9,998 participants from the National Health and Nutrition Examination Survey 2011–2018 were included. Lean mass percentage (LM%) and FM% were evaluated by dual-energy x-ray absorptiometry. Obesity was defined as body FM% ≥25% in men and ≥ 35% in women. The OBS was scored by 5 pro-oxidant and 21 antioxidant factors. Associations of quartiles of OBS with obesity risk were estimated using multivariable logistic regression models. Multivariable linear regression was conducted to estimate the association between OBS and segmental body composition measures including the arm LM%, leg LM%, torso LM%, whole LM%, arm FM%, leg FM%, torso FM% and total FM%.ResultsCompared to participants in the lowest quartile of OBS, those in the highest quartile of OBS were associated with a lower risk of BMI-defined obesity BMI-defined obesity [0.43 (0.36, 0.50)] and FM%-related obesity [0.43 (0.35, 0.52)]. Additionally, OBS was negatively associated with FM% of the limb and torso but positively associated with the percentage of lean mass (LM%) of the limb and trunk.ConclusionOBS was negatively associated with the risk of obesity and segmental FM%, but was positively associated with segmental LM% among US adults, indicating that adhering to an anti-oxidative diet and lifestyle management may be beneficial for preventing segmental obesity.</p

Unidirectional Freezing of Ceramic Suspensions: In Situ X‑ray Investigation of the Effects of Additives

Using in situ X-ray radiography, we investigated unidirectional freezing of titanium dioxide suspensions. We showed how processing additives, which are generally used for ice-templating, strongly modified freezing dynamics during the solidification process. We observed and identified different freezing regimes by varying the amount of dispersant, binder, or poly­(ethylene glycol) (PEG). We demonstrated that because each regime corresponds to a given final structure understanding the particle motion and redistribution at the ice-front level was essential. We also examined the transition from a random particles-entrapment regime to a well-defined lamellar regime and proposed and discussed two mechanisms by which additives might affect the solidification process

Unidirectional Freezing of Ceramic Suspensions: In Situ X‑ray Investigation of the Effects of Additives

Using in situ X-ray radiography, we investigated unidirectional freezing of titanium dioxide suspensions. We showed how processing additives, which are generally used for ice-templating, strongly modified freezing dynamics during the solidification process. We observed and identified different freezing regimes by varying the amount of dispersant, binder, or poly­(ethylene glycol) (PEG). We demonstrated that because each regime corresponds to a given final structure understanding the particle motion and redistribution at the ice-front level was essential. We also examined the transition from a random particles-entrapment regime to a well-defined lamellar regime and proposed and discussed two mechanisms by which additives might affect the solidification process