The development of a new copolymer, combining sugar-based with oil-based macromolecules, makes it possible to design ultra-thin films capable of self-organization on a scale of just 5 nm. This opens up new horizons for increasing the capacity of hard discs and the speed of microprocessors.
The result of a French-American collaboration spearheaded by the Centre National de la Recherche Scientifique (CNRS), this work, published in ACS Nano, has led to the filing of two patents. This new class of thin films based on hybrid copolymers could give rise to numerous applications in flexible electronics, in areas as diverse as nanolithography, biosensors and photovoltaic cells.
Before new generations of microprocessors can be devised, lithography, the technique used for printing electronic circuits, must undergo significant evolution, to allow ever smaller circuit architecture. Until now, the thin films used in electronic circuits have been designed from synthetic polymers exclusively derived from petroleum. However, these thin films have limitations: their minimum structural resolution is around 20 nanometers and cannot be reduced further by combining petroleum-derived polymers. This limit has been one of the main obstacles to the development of new generations of very-high-resolution flexible electronic devices.
This limit arises from the low incompatibility between the two blocks of polymers, both derived from petroleum oil. For that reason, the team headed by Redouane Borsali, CNRS senior researcher at the Centre de Recherches sur les Macromolécules Végétales (CERMAV), came up with a hybrid material, combining sugar-based and petroleum-derived (silicon-containing polystyrene) polymers with widely different physical and chemical characteristics. This copolymer, formed of highly incompatible elementary building blocks, is similar to an oil bubble attached to a small water bubble. The researchers have shown that this type of structure is capable of organizing itself into sugar cylinders within a petroleum-based polymer lattice, each structure having a size of 5 nanometers, i.e. much smaller than the resolution of "old" copolymers, exclusively composed of petroleum derivatives. In addition, this new generation of material is made in part from an abundant, renewable and biodegradable resource: sugar.
Achieving this resolution makes it possible to envisage numerous applications in flexible electronics: miniaturization of circuit lithography, a six-fold increase in information storage capacity (the theoretical limit for devices using flash memory, such as USB memory sticks, would increase from 1Tb to 6Tb), enhanced performance of photovoltaic cells, biosensors, etc. The researchers are now seeking to improve control of these nano-glycofilms' large-scale organization and design in different self-organized structures.
These results follow prior work carried out by CERMAV within the framework of the Grenoble RTRA (Thematic Network of Advanced Research) - "Nanosciences at the limits of nanolectronics".