Material extrusion (MEX) is widely used in additive manufacturing due to its simplicity and compatibility with various thermoplastics. While adhesive coating is commonly applied to enhance the watertightness of MEX-fabricated (MEXed) structures, its impact on mechanical properties remains unclear. This study investigated the effect of cyanoacrylate adhesive dip coating on the mechanical behavior of MEXed polylactic acid (PLA) specimens. Tensile specimens were fabricated in both longitudinal and transverse orientations and coated with two commercial cyanoacrylate adhesives, Loctite 401 and Alaska 4001. The coating process was repeated 2, 4, and 6 times, followed by cross-sectional observations and tensile testing. The results indicated that the cross-sectional area increased with an increasing number of coating repetitions, regardless of adhesive type or infill pattern. Tensile strength generally decreased after coating, with reductions of 10.6–14.7% after six coating cycles. In contrast, the elongation at break increased after coating treatment. For Loctite 401, the maximum increases were approximately 35.1% and 124.1% for the longitudinal and transverse specimens, respectively, while Alaska 4001 resulted in maximum increases of approximately 29.7% and 48.3%, respectively. These findings suggest that adhesive dip coating significantly alters the mechanical behavior of MEXed PLA structures and requires optimization to balance strength and ductility.

Purification of water through oil–water separation is essential for preserving the ecosystem and protecting human health. Although a conventional polypropylene depth filter can effectively purify water, modifying the wettability of a filter for oil–water separation is difficult owing to its low reactivity. In this study, we developed a superhydrophilic polypropylene filter with a hydrogel layer that could enable effective oil–water separation by using plasma treatment and dip coating, which enabled an even distribution of the coating solution across the filter. The fabricated filter was superhydrophilic with a water contact angle of 0o. It showed a high repulsive force with oil in water with an underwater oil contact angle of 142.9o. When such filter was applied to an oil–water separation device, it effectively purified water with low oil content (< 15 ppm) at a flow rate of 300 mL/min. These results demonstrate potential applications of such filters in areas such as wastewater treatment and oil spill cleanup.

Three-dimensional (3-D) printing, with its capability for producing arbitrary shapes, has shown great potential for usage in patient-specific tissue engineering. However, if artificial tissues are fabricated directly through typical 3-D printing processes, the mechanical properties, particularly for softness or flexibility, significantly differ from those of natural tissues, resulting in inappropriate side effects during surgeries using vascular grafts. However, this can be overcome through the indirect 3-D printing of templates created with a thin-film formation process, such as dip coating. Dip coating is performed in two steps, including dipping/withdrawing a target base template from a polymer solution, and then drying the solvent into a solid thin film on the template. However, it is difficult to form a uniform layer on the arbitrary template because the gravitational flow of the coated solution disturbs the uniformity of the template as the solvent is drying. Therefore, we minimized the flow around the template after dip coating by rapidly removing the solvent removal by dipping the solution-coated template into ethanol. This reduced the solvent removal time and increased the viscosity of the coated solution, thereby alleviating the gravitational flow of the coated solution, and allowing us to successfully fabricate flexible vascular grafts.