Introduction

By exposing synthetic polymers, in the form of continuous or micro/nano-structured membranes, supported or self-standing, to alkaline solutions, it’s possible to achieve their carbonization by laser-CO2-writing under ambient-conditions (without inert gas in contact with material), resulting in electrically conductive patterns. Most engineering polymers do not allow the development of conductive patterns under ambient conditions through carbonisation induced by laser-CO2 writing in continuous mode. In fact, carbonisation processes can always be conducted in an oven in a controlled atmosphere, but without the time and process advantages associated with laser-CO2 writing, resulting in spatially selective carbonisation to produce carbon patterns.

Technical features

The invention (TRL 3) demonstrates how it is possible to induce carbonization by laser under ambient conditions to any polymer-synthetic after treatment with alkaline hydroxide solutions prior to exposure to laser-CO2 radiation. The invention provides:

• Formation of nano- or micro-structured polymeric films/fibres, implementing electrospinning (or electrospinning) process to achieve the deposition of nanostructured polymeric membranes;
• Treatment with alkaline solutions, containing hydroxides at low concentrations (0.05M-0.1M), of the polymeric based fibres/films, for which there is no technological solution that allows direct laser writing of conductive tracks in ambient atmosphere. PAN and PVDF are selected as application example due to their carbonisation yields in standard (oven) treatments;
• On processed samples, the carbonisation induced by writing with laser-CO2 (λ=10.6 µm) is studied in continuous mode, creating conductive tracks or patterns written directly by laser, transforming the material only in the areas interacting with the laser.

Possible Applications

• ENERGY: production of electrodes, including flexible ones, for production devices – fuel cells and storage – batteries and supercaps, including wearable ones;
• SENSORISTICS: production of electrodes, including flexible ones, for electrochemical sensors, also of the wearable type.

Advantages

• Speed and flexibility of the process;
• Time, cost and sustainability resulting from the absence of technical gases;
• Creation of conductive pattern-paths in a localised manner;
• Possibility of converting synthetic polymers into carbonaceous-porous material in an ambient.