Dahu Yao

Bio: Dahu Yao is an academic researcher from Chonbuk National University. The author has contributed to research in topics: Materials science & Graphene. The author has an hindex of 3, co-authored 3 publications receiving 2784 citations. Previous affiliations of Dahu Yao include Henan University of Science and Technology.

Lipase‐catalyzed synthesis and characterization of biodegradable polyester containing l‐malic acid unit in solvent system

Abstract: Lipase-catalyzed direct polycondensation of L-malic acid (L-MA), adipic acid, and 1,8-octanediol in organic media was achieved using Novozym 435 as the biocatalyst. 1H-nuclear magnetic resonance spectroscopy indicated that the selectivity of Novozym 435 was unaffected by changes in the organic media. The molecular weight (Mw) of the copolymers was affected by the L-MA feed ratio in the diacids, hydrophobicity of the solvent, and solubility of the substrates in the solvents. The Mw reached a maximum of 17.4 kDa at 80°C in isooctane at a L-MA feed ratio in the diacids of 40 mol %. The Mw increased from 3.2 to 16.6 kDa when the reaction time was extended from 6 to 48 hr at 70°C, and remained relatively constant with further increases in reaction time from 48 to 72 hr. The hydrophilicity, thermal stability, and crystallizability of the copolymer were also investigated. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

Effect of reactive poly(ethylene glycol) flexible chains on curing kinetics and impact properties of bisphenol‐a glycidyl ether epoxy

Abstract: Bisphenol-A glycidyl ether epoxy resin was modified using reactive poly(ethylene glycol) (PEO). Dynamic mechanical analysis showed that introducing PEO chains into the structure of the epoxy resin increased the mobility of the molecular segments of the epoxy network. Impact strength was improved with the addition of PEO at both room (RT) and cryogenic (CT, 77 K) temperature. The curing kinetics of the modified epoxy resin with polyoxypropylene diamines was examined by differential scanning calorimetry (DSC). Curing kinetic parameters were determined from nonisothermal DSC curves. Kinetic analysis suggested that the two-parameter autocatalytic model suitably describes the kinetics of the curing reaction. Increasing the reactive PEO content decreased the heat flow of curing with little effect on activation energy (Ea), pre-exponential factor (A), or reaction order (m and n). © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

Hydrophobic Multifunctional Flexible Sensors with a Rapid Humidity Response for Long-Term Respiratory Monitoring

Abstract: Slow humidity response and poor tolerance to high humidity environments limit the application of humidity sensors for respiratory monitoring. Herein, a flexible humidity sensor with a structure composed of multiwalled carbon nanotubes (MWCNTs) firmly attached to the surface wrinkles of a natural latex film was fabricated by a simple swelling-self-assembly method. The weak interaction bond between MWCNTs and water molecules affords the sensor a humidity response time that is as low as 0.7 s and a wide humidity detection range (0–100%), enabling it to be used to accurately detect human respiration at a frequency of 1 Hz. The wrinkled structure of the sensor surface increases the contact area between the MWCNTs and the airflow, thus improving the sensitivity to humidity in the airflow. The near-superhydrophobic surface (contact angle = 143.5°; roll-off angle = 5°) enables the sensor to be used to accurately detect human respiration for extended periods of time in high humidity environments. The firmly attached MWCNTs ensure the stability and robustness of the sensor for humidity detection. In addition, the sensor can be used to detect trace organic solvents in water in a noncontact mode. The above advantages enable the sensor to be used to monitor a user’s respiration in real time and even to identify the vocal characteristics of the user, indicating its potential application in wearable devices.

Recent Advances in Ultrathin Two-Dimensional Nanomaterials

Abstract: Since the discovery of mechanically exfoliated graphene in 2004, research on ultrathin two-dimensional (2D) nanomaterials has grown exponentially in the fields of condensed matter physics, material science, chemistry, and nanotechnology. Highlighting their compelling physical, chemical, electronic, and optical properties, as well as their various potential applications, in this Review, we summarize the state-of-art progress on the ultrathin 2D nanomaterials with a particular emphasis on their recent advances. First, we introduce the unique advances on ultrathin 2D nanomaterials, followed by the description of their composition and crystal structures. The assortments of their synthetic methods are then summarized, including insights on their advantages and limitations, alongside some recommendations on suitable characterization techniques. We also discuss in detail the utilization of these ultrathin 2D nanomaterials for wide ranges of potential applications among the electronics/optoelectronics, electrocat...

Ultrathin Two-Dimensional Nanomaterials.

Abstract: The past decade has witnessed an extraordinary increase in research progress on ultrathin two-dimensional (2D) nanomaterials in the fields of condensed matter physics, materials science, and chemistry after the exfoliation of graphene from graphite in 2004. This unique class of nanomaterials has shown many unprecedented properties and thus is being explored for numerous promising applications. In this Perspective, I briefly review the state of the art in the development of ultrathin 2D nanomaterials and highlight their unique advantages. Then, I discuss the typical synthetic methods and some promising applications of ultrathin 2D nanomaterials together with some personal insights on the challenges in this research area. Finally, on the basis of the current achievement on ultrathin 2D nanomaterials, I give some personal perspectives on potential future research directions.