Surface Wettability Tuning of Acrylic Resin Photoresist and Its Aging Performance

Abstract

Photoresist is the key material in the fabrication of micropatterns or microstructures. Tuning the surface wettability of photoresist film is a critical consideration in its application of microfluidics. In this work, the surface wettability tuning of acrylic resin photoresist by oxygen plasma or ultra-violet/ozone, and its aging performance in different atmospheres, were systematically studied. The chemical and physical characterizations of the surfaces before and after modification show a dramatic decrease in the C–C group and increase in surface roughness for oxygen plasma treatment, while a decrease of the C–C group was found for the UV/ozone treatment. The above difference in the surface tuning mechanism may explain the stronger hydrophilic modification effect of oxygen plasma. In addition, we found an obvious fading of the wettability tuning effect with an environment-related aging speed, which can also be featured by the decrease of the C–C group. This study demonstrates the dominated chemical and physical changes during surface wettability tuning and its aging process, and provides basis for surface tuning and the applications in microfluidics.

How to Make Plastic Surfaces Simultaneously Hydrophilic/Oleophobic?

“…In Figure 2a, the peaks located at 1757 and 1249 cm −1 are assigned to C�O and C−O−C stretching vibrations of ester groups of PMMA, respectively. 43,52 After UV/Ozone treatment, the intensity of these two peaks noticeably decreases; meanwhile, higher intensities are observed at the peak shoulders in the ranges of 1000−1125 and 1600−1800 cm −1 , suggesting the photolysis of ester groups yields oxygen-containing polar groups such as carboxylic acids, aldehydes, ketones, and alcohols. 43 The appearance of the peak at 3000−3600 cm −1 , which is attributed to OH stretching, also indicates the generation of hydroxyl groups after UV/Ozone treatment.…”

“…It has been widely reported that plastics conventionally treated by plasma and UV/Ozone will experience hydrophobic recovery with time, i.e., their WCA increases back to the value before the treatment. ,,, It has been proposed that airborne hydrocarbon can adsorb on plastic surface and thus lowers the surface energy and increases the WCA . Aging tests were conducted on our Zdol-coated and UV/Ozone-treated plastics with simultaneous hydrophilicity/oleophobicity.…”

“…The approaches to modify plastic’s surface wettability can be divided into two categories: surface activation and surface coating . Oxygen plasma and UV/Ozone are two of the most common surface activation treatments to enhance the surface energy of plastic by introducing oxygen-containing polar groups. ,,, However, it has been shown by many previous reports that such enhancement will degrade with time, and the WCA of aged polymer surfaces will increase toward the original value, also known as hydrophobic recovery. ,,, Surface coating can be achieved via either vapor deposition or wet chemical coating process. , Chang et al spin-coated PMMA with a UV-curable bilayer structure composed of a silica-embedded crosslinked network of dipentaethritol hexaacrylate (DRHA) as the hydrophobic barrier, and a hydrophilic top layer synthesized from Tween-20, isophorone diisocyanate (IPDA), and 2-hydroxyethyl methacrylate (2-HEMA) . They reported a WCA of ∼0° and superb antifogging performance as increasing the Tween-20 content at the expense of mechanical strength and coating adhesion .…”

Influence of light induced accelerated ageing on surface properties of cardboard packaging coated by tio2 nanocomposites

“…WB samples, after 30h AcA have lower polar component but higher total SFE values. This can be attributed to the acrylic resin that is a common ingredient in water based varnishes and it tends to become more hydrophobic after exposure to UV or ozone (Dou et al, 2021). On the other hand, with the increase of TiO2 nanoparticle weight ratio (%), the wettability of TiO2 coated samples also increases but after the AcA it lowers.…”

Process Optimization of Single-Step Photolithography

“…We compared the thicknesses of photoresist produced in 2021 and 2022 as the following, and we found that the one-year storage increases the thickness by about 0.2um on average (Table 3. ), since the photoresist is easily affected by light exposure and high temperature during the storage [8]. Therefore, the expired photoresist must be avoided to achieve the desired experiment results.…”