Synthesis, structure, and properties of bisphenol A formaldehyde sol—precursor of low-density aerogel

• Published in: Colloid and polymer science 2018-08, Vol.296 (8), p.1313-1322
• Main Authors: Sheveleva, Elena Evgenievna, Pimenov, V. G., Blagodatskikh, I. V., Vyshivannaya, O. V., Abramchuk, S. S., Sakharov, A. M.
• Format: Article
• Language: English
• Subjects: Aerogels; Bisphenol A; Characterization and Evaluation of Materials; Chemistry; Chemistry and Materials Science; Clusters; Complex Fluids and Microfluidics; Crosslinking; Density; Dynamic structural analysis; Food Science; Formaldehyde; Fractals; Heat treatment; Hydrogels; Molecular chains; Molecular weight distribution; Nanotechnology and Microengineering; Original Contribution; Physical Chemistry; Polymer Sciences; Scanning electron microscopy; Size exclusion chromatography; Soft and Granular Matter; Transmission electron microscopy
• ISSN: 0303-402X; 1435-1536
• DOI: 10.1007/s00396-018-4343-6

Low-density organic aerogels (down to 11–12 mg/cm 3 ) were successively synthesized by polycondensation of formaldehyde with bisphenol A (2,2-diphenylolpropane or BPhA) methylol derivatives by the thermal treatment under basic conditions. In this paper, the main features of bisphenol A-formaldehyde (BF) sol and hydrogel formation have been examined for the first time. The molecular weight distribution both of the initial resin and the soluble products of its thermal processing were studied by size exclusion chromatography. A detailed study of the structure of sols and the dynamics of its change was carried out by dynamic and static light scattering and scanning and transmission electron microscopy. The results obtained allowed to describe the process of gel formation as a diffusion-limited cluster-cluster fractal aggregation of sol nanoparticles formed during the polycondensation. Crosslinking of low-density fractal aggregates leads to the formation of a macro-porous structure with a high pore volume and, ultimately, to a low-density aerogel.