Mastrangelo Rosangela, Resta Claudio, Carretti Emiliano, Fratini Emiliano, Baglioni Piero
Department of Chemistry and CSGI, University of Florence, via della Lastruccia, 3, Sesto Fiorentino, Florence 50019, Italy.
ACS Appl Mater Interfaces. 2023 Oct 4;15(39):46428-46439. doi: 10.1021/acsami.3c03239. Epub 2023 Jul 29.
Macroporous gels find application in several scientific fields, ranging from art restoration to wastewater filtration or cell entrapment. In this work, two-component sponge-like cryogels are challenged to assess their cleaning performances and to investigate how pores size and connectivity affect physico-chemical properties. The gels were obtained through a freeze-thaw process, exploiting a spontaneous polymer-polymer phase-separation occurring in the pre-gel solution. During the freezing step, a highly hydrolyzed polyvinyl alcohol (H-PVA) forms the hydrogel walls. The secondary components, namely a partially hydrolyzed polyvinyl alcohol (L-PVA) or polyvinyl pyrrolidone (PVP), act as modular porogens, being partially extracted during gel washing. H-PVA/L-PVA and H-PVA/PVP mixtures were studied by confocal laser scanning microscopy to unveil sols and gels morphology at the micron-scale, while small angle X-ray scattering was used to get insights about characteristic dimensions at the nanoscale. The gelation mechanism was investigated through rheology measurements, and the characteristic exponents were compared to De Gennes' scaling laws gathered from percolation. In the field of art conservation, these sponge-like gels are ideal systems for the cleaning of artistic painted surfaces. Their interconnected pores allow the diffusion of cleaning fluids at the painted interface, facilitating dirt uptake and/or detachment. This study uncovered a direct relationship linking a gel's cleaning performance to its apparent tortuosity. These findings can pave the way to fine-tuning systems with enhanced cleaning abilities, not restricted to the restoration of irreplaceable priceless works of art, but with possible application in diverse research fields.
大孔凝胶在多个科学领域都有应用，从艺术品修复到废水过滤或细胞截留。在这项工作中，对两组分海绵状冷冻凝胶进行了测试，以评估其清洁性能，并研究孔径和连通性如何影响物理化学性质。这些凝胶是通过冻融过程获得的，利用了预凝胶溶液中发生的自发聚合物-聚合物相分离。在冷冻步骤中，高度水解的聚乙烯醇（H-PVA）形成水凝胶壁。次要成分，即部分水解的聚乙烯醇（L-PVA）或聚乙烯吡咯烷酮（PVP），充当模块化致孔剂，在凝胶洗涤过程中被部分提取。通过共聚焦激光扫描显微镜研究了H-PVA/L-PVA和H-PVA/PVP混合物，以揭示微米级的溶胶和凝胶形态，同时使用小角X射线散射来了解纳米级的特征尺寸。通过流变学测量研究了凝胶化机制，并将特征指数与从渗流中收集的德热纳标度定律进行了比较。在艺术品保护领域，这些海绵状凝胶是清洁艺术绘画表面的理想体系。它们相互连接的孔隙允许清洁液在绘画界面扩散，便于污垢吸收和/或分离。这项研究揭示了凝胶的清洁性能与其表观曲折度之间的直接关系。这些发现可以为微调具有增强清洁能力的系统铺平道路，不仅限于修复不可替代的无价艺术品，还可能应用于不同的研究领域。
