Abstract
Based on the contact angle prediction model of a traditional square column structure, the prediction models for wettability of a parallelogram square column structure (PSCS) on polymethyl methacrylate (PMMA) surface prepared by femtosecond laser were established. An experiment was conducted to analyze the rationality of the established complete wetting model and incomplete wetting model. It was found that the incomplete wetting prediction model of the square column structure was more in line with the actual situation. For PSCS, the length of both the long and short sides of the boss and the width of the groove exerted an impact on the contact angle prediction results. Under the condition that the length of the long and short sides of the boss remained unchanged and the groove width increased, the contact angle increased under complete wetting and incomplete wetting. In contrast, under the condition that the long side length of the boss and the groove width remained unchanged and the short side length of the boss increased, the contact angle increased under complete wetting but decreased under incomplete wetting. The maximum contact angle reached 135.65°, indicating that PSCS on PMMA surface enhanced the surface hydrophobicity of the material.
Highlights
IntroductionPublisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations
The results suggest that the established prediction model is reasonable, and the structural parameters play a guiding role in improving surface structure hydrophobicity of the polymer polymethyl methacrylate (PMMA)
This is because the femtosecond laser beam has a Gaussian distribution and the laser pulse repetition frequency is much greater than the critical frequency, which led to accumulation of laser heat and thermal degradation of PMMA
Summary
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. The chemical and mechanical processing methods mentioned above have been widely used to prepare hydrophobic surface microstructures, the wettability of some microstructures needs to be further improved, and the prediction law of contact angle needs to be further studied. Wang et al [19] used laser to process the PMMA surface and prepare grating and square column microstructures and established a complete wetting model and an incomplete wetting model for experimental studies. They found that the microstructure had better hydrophobicity when the ratio of boss width to groove width was small and the spacing between the top edges was large. The results suggest that the established prediction model is reasonable, and the structural parameters play a guiding role in improving surface structure hydrophobicity of the polymer PMMA
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