Nanocomposite film from sugarcane waste, PMMA film with sensor detects toxic gas

Sugarcane waste has been utilized to produce nanocomposite film with unique physical and mechanical properties. The film, with multiple applications in packaging, glue making, medicine and electronic industries, has been developed by researchers from University of Tehran. These nanofibers have simpler, faster and more cost-effective production method in comparison with other production methods. The size of the produced cellulose nanofiber has been reported about 39±13nm while tension resistant of the nanocomposite produced from the nanofibers has been reported about 140 MPa. The produced nanocomposite has higher strength in comparison with the majority of biodegradable and non-biodegradable films. It seems that the produced nanocomposite can be considered an appropriate option for the elimination of artificial polymers and oil derivatives from packaging materials. Cellulose fibers were produced through mechanical milling method after separation and purification of cellulose from sugarcane bagasse, resulting in production of nanopapers. Next, full cellulose nano composite was produced through partial dissolving method, and its characteristics were evaluated. Results showed that as the time of partial dissolving increases, the diffusivity of the nano composite into vapor decreases due to the increase in glassy part (amorphous) to crystalline part. However, thermal resistance decreases as the time of partial dissolving increases because a decrease is observed in the crystalline part. In addition, when cellulose microfibers turn into nanofibers, resistance against the tension of the produced films increases. The researchers believe that the reason for the increase is the reduction in fault points (points that lead to the fracture in cellulose fibers), increase in specific area, and integrity of nanofibers. Transparency of samples significantly increases as the size of particles decreases to nanometric scale.

Those who work with hazardous substances could find an extra measure of protection in an optical sensor that puffs up in the presence of even trace amounts of toxic gases. Made from a 400 nm thick film of polymethyl methacrylate (PMMA), the sensors are infused with fluorescent dye and patterned with 1-D photonic crystal cavities suspended in air, as published in Applied Physics Letters. Certain gases cause the PMMA to swell, changing the optical resonance of the cavities and producing minute color changes in the polymer detectable by a spectral filter. Researchers at MIT said they achieved an experimental sensitivity of 10 ppm and predict detection levels in the parts-per-billion range for a variety of gases. “Because of their deformation in response to biochemical substances, cavity sensors made entirely of this polymer lead to a sensor with faster response and much higher sensitivity," said Hannah Clevenson, an MIT doctoral student who led the study. Isopropyl alcohol vapor was used in the laboratory, but the researchers said the sensor can detect any gas that interacts with PMMA. The polymer shrinks back to its original size once the targeted gas has been removed, meaning the sensors can be reused, the researchers said. Optical sensors are suited to detecting trace gas concentrations due to their high signal-to-noise ratio, compact, lightweight nature and immunity to electromagnetic interference, the researchers said. Clevenson said potential applications for the sensor range “from industrial sensing in large chemical plants for safety applications, to environmental sensing out in the field, to homeland security applications for detecting toxic gases, to medical settings, where the polymer could be treated for specific antibodies.”