Directional, Silanized Plant-Based Sponge for Oil Collection

Porous materials are commonly employed to combat marine pollution by absorbing oil. However, the release of microplastics or nanoparticles from their synthetic components further exacerbates environmental concerns. In this study, a sustainable and reusable pollen sponge derived from eco-friendly pollen grains and fabricated using a directional freeze-drying method is introduced for the first time. These grains undergo a defatting process followed by a controlled hydrolysis process, transforming them into a pollen microgel made of sporopollenin, the primary constituent of a pollen grain's outer layer. The directional freeze-drying technique is used to fabricate porous structures with controlled orientation using the pollen microgel. The application of a chemical vapor deposition with dodecyltrimethoxysilane (DDTS) grants sponge hydrophobic properties, making it ideal for selective oil absorption. This modified pollen sponge boasts superior absorption capacities (15–59 times its weight) compared to most natural sponges. Additionally, its excellent durability and ability to recover up to 65% of deformation even after 60% strain compression are remarkable with the silanization process tripling the recoverability of pollen sponges. Remarkably, the silanized directional pollen sponge (SDPS) retains this resilience after 100 compression cycles. Therefore, the SDPS emerges as an eco-conscious solution for repeated and selective oil absorption tasks.