“Second Skin” to serve soldiers

In modern combat situations, soldiers in the field need protection from biological and chemical agents. At the same time, their protective clothing is a hindrance if it is too hot to wear or unnecessarily burdensome.

Scientists at the Lawrence Livermore National Laboratory, Livermore, Calif., have developed a material that shows promise for futuristic smart uniforms. Dubbed Second Skin, it is highly breathable yet protects against biological agents. The material is also being developed to protect against environmental chemical hazards.

The laboratory team fabricated flexible polymeric membranes with aligned carbon nanotube (CNT) channels as moisture conductive pores. The size of these pores is 5,000 times smaller than the width of a human hair; the extremely small pore size is what provides protection from biological threats like bacteria or viruses, which are much larger.

The membranes provide rates of water vapor transport that surpass those of commercial breathable fabrics even though the CNT pores are only a few nanometers wide, making the fabric highly breathable.

To protect against chemical agents, which are smaller in size and require the membrane pores to be able to react to block the threat, the researchers are looking at ways to encode the membrane with a smart and dynamic response, surface modifying the prototype carbon nanotube membranes with chemical-threat-responsive functional groups that sense and block the threat like gatekeepers on the pore entrance. A second response scheme that enables the fabric to exfoliate upon reaction with the chemical agent is also in development.