Polymethylsiloxane alone and in composition with nanosilica under various conditions

Disperse polymethylsiloxane (PMS) alone and in a mixture with highly disperse nanosilica A-300 was studied as a dry powder and a hydrogel located in various dispersion media (air, chloroform alone and with addition of trifluoroacetic acid) using low-temperature ¹H NMR spectroscopy, cryoporometry, thermogravimetry, nitrogen adsorption, microscopy, infrared spectroscopy, and quantum chemistry. The powders of dried PMS and PMS/A-300 can be easily rehydrated upon strong stirring with added water. The slurry properties depend on mechanical treatment features due to stronger compaction of the secondary structures with increasing mechanical loading. The organization of bound water (at a constant hydration degree h = 1 g/g) depends strongly on the dispersion media (because chloroform can displace water from narrow interparticle voids into broader ones or into pores inaccessible for larger CDCl₃ molecules) and mechanical loading reorganizing aggregates of PMS and A-300 nanoparticles (<1 μm in size) and agglomerates (>1 μm) of aggregates. The PMS/nanosilica blends could be of interest from a practical point of view due to additional control of the textural and structural characteristics determining efficiency of sorbents with respect to low- and high-molecular weight compounds depending on the dispersion media that is of importance, e.g., for medical applications.