Abstract
For several decades, organic/inorganic composite materials have garnered increasing interest in research due to their unique properties that combine the benefits of both worlds. These hybrid materials hold significant potential for applications in fields such as optics, microfluidics, and microelectronics. Their synthesis is achieved in a cost-effective two-step process: first, the inorganic network is generated via a sol-gel process, while the organic phase, consisting of negative or positive resins, undergoes crosslinking through UV irradiation or appropriate thermal initiators. Laser writing lithography, which enables micron-scale precision, has emerged as an efficient method for fabricating microstructures without the need for masks. However, while this technique is well-suited to negative resins, it has limitations when used for large-scalesurfaces due to the lengthy process times, making it costly and complex for applications such as microfluidic devices. These devices often require large areas to be exposed in order to create micron-sized channels. The use of positive resins in combination with laser writing offers a more viable solution, as they simplify microstructuring processes. The primary objective of this work is to synthesize, optimize, and implement aphotosensitive hybrid material in the form of a positive-tone resin, tailored for microfabrication. Chemically amplified resins, widely used in high-density microlithography due to their efficiency and submicron precision, are explored here for their application in microfluidic devices. We have developed a series of hybrid resins based on acrylate-polysiloxane, capable of achieving thicknesses of up to 40 μm. These resins, when combined with photo-acid generators, here the iodonium/tetrakis(pentafluorophenyl)borate, they exhibit outstanding performance as positive-tone resists, while being developable in aqueous environments.The materials synthesized are derived from Tert-butyl methacrylate (TBMA) and the hybrid precursor 3-(Trimethoxysilyl)propyl methacrylate (MAPTMS), with each component playing a specific role in the final resin formulation. The copolymerization of TBMA with MAPTMS enables the bonding of the methacrylate group in MAPTMS, which contains a polymerizable organic unit (C=CH2), to the TBMA. This approach aims to increase deposition thickness and enhance the mechanical and chemical properties of the resin. Additionally, the presence of inorganic groups, resulting from the hydrolysis of MAPTMS, improves adhesion through silanol groups (-SiOH). The photochemical process relies on cationic acid chemistry, where acid-catalysed removal of a protected organic group leads to the formation of water-soluble functionalities, such as carboxylic acids or alcohols, facilitating the development of complex patterns.