| Abstract [eng] |
Structurization of Epoxidized Acrylated Soybean Oil Employing Optical 3D Lithography Optical technologies were implemented for rapid prototyping since the middle eighties. At first, it was known as stereolithography (SLA) – three dimensional (3D) macroscale (mm, cm, m) models’ and prototypes’ manufacturing based on photochemical reaction. During the decades SLA has evolved to bench-top and table-top devices, known as optical 3D printers (O3DP). Surpassing to SLA, a technology to produce microscale objects with nm precision has emerged. It is known as nonlinear laser lithography (NLL) and is based on nonlinear light-matter interaction. Due to this NLL requires femtosecond laser sources and tight focusing. Both technologies can be called general name optical 3D lithography (O3DL). Despite their fundamental and technological differences, the common issue remains the same – the choice of materials. Naturally derived products have taken a place of interest. For example, epoxidized acrylated soybean oil (EASO) is widely used in industry because of high amount of various functional groups (acrylic, epoxy and hydroxy). This work goal is to present photostructuring of plant-based EASO for O3DL. Investigation of EASO suitability for the SLA was performed employing two O3DP (385 nm and 405 nm wavelengths). Three different photoinitiators (PI) were used to photosensitize the EASO. Light penetration depth ha and critical duration Tc, required to fully polymerize a certain resins’ layer, were assessed by Beer-Lambert law. Amount of PI affect to the ha and Tc was evaluated as well. For the NLL, 515 nm (fundamental 1030 nm) fs laser irradiation with high pulse repetition rate (200 kHz) was employed. Varying irradiation power P, beam scanning velocity v and distance between adjacent beam scans dxy, there were estimated parameters to produce well-defined structures of appropriate precision. The highest achievable spatial resolution and efficiency expressed in volumetric pixels (voxels) per second were assessed. We showed, that photosensitized EASO can be selectively polymerized employing linear absorption with table-top O3DP. Measured ha and Tc were higher for 405 nm light: 400 μm > 260 μm and 0.8 s > 0.4 s (1 % w/w PI). Increasing amount of PI from 0.25 to 2 % w/w, ha can be controlled from 700 μm to 200 μm and Tc – 1-0.2 s. Nonphotosensitized EASO can be structurized using NLL due to nonlinear interaction. Evaluated fabrication parameters were: P = 0.4–1.2 mW,when v = 2.5-10 mm/s and dxy = 0.25-1.5 μm. Achieved highest spatial resolution was 1-1.2 μm in lateral and 2 μm in longitudinal dimension. It resulted to the 15000 voxels/s efficiency. Photostructuring of EASO was demonstrated. Evaluated parameters showed great perspectives to apply EASO in O3DL technologies as a resin derived from natural resources. |
