Activatable Multizone Hybrid Hydrogels Containing Porous Organosilica Nanoparticles as Gatekeepers

• Published in: Chemistry of materials Vol. 35; no. 20; pp. 8406 - 8416
• Main Authors: Kollofrath, Dennis, Krysiak, Yaşar, Polarz, Sebastian
• Format: Journal Article
• Language: English
• Published: American Chemical Society 24.10.2023
• ISSN: 0897-4756; 1520-5002
• DOI: 10.1021/acs.chemmater.3c01125

Because the supply of clean water is one of the biggest challenges that we already face today, it is becoming increasingly important to develop smart strategies to purify sewage. Every wastewater is different and typically contains a large number of different contaminations. Adsorbents with a high surface area represent a powerful way to remove such compounds from a liquid. But, there are also several problems. An unselective adsorbent will bind everything and thus become a hazardous waste itself. If the adsorbent is selective, then several adsorbents are needed to treat the wastewater and achieve sufficient purification. The idea of the current paper is to develop a material that is capable of the uptake of different contaminants from a mixture; it then automatically separates in a multizone-structure. The impurities can be removed separately, step by step, by recycling the materials. Porous vinyl-functionalized organosilica nanoparticles are the key to creating the required anisotropy in selectivity when used as cross-linkers in hydrogels formed by a thermoresponsive polymer. The tailor-made functionalization of the pore surfaces allows for precise tuning of the host−guest interactions. It is shown that the presence of porous particles is a crucial factor for mass transport. The distance between them can be controlled by temperature-induced switching of the polymer from the swollen to the collapsed state. The smaller the distance between the porous particles, the more interparticle mass transport occurs. The correlating active pump effect, in combination with the multizone structure, allows switching separation on and off. The materials presented herein can be considered to be a model for a new generation of chromatography materials with variable and externally controllable separation properties.