Nanoporous polymer networks of N − vinylpyrrolidone with dimethacrylates of various polarity. Synthesis, structure, and properties

Nanoporous polymer networks of N − vinylpyrrolidone (VP) with dimethacrylates of ethylene, 1,6 − hexanediol and triethylene glycol were obtained by three-dimensional free-radical copolymerization in bulk using branched copolymers as pores templates. The branched copolymers consisted of monomers of the same type to provide their thermodynamically compatibility and solubility in the appropriate mixtures of VP − dimethacrylate. They were synthesized by radical copolymerization in toluene under chain transfer condition and characterized by the FTIR, 1H NMR, GPC, DSC and DLS methods. After curing of the stable visually homogeneous monomer-polymer mixtures, polymer composites with optical properties differed from conventional network copolymers were obtained due to the micro- or macrophase separation. According to the gravimetry, FTIR, GPC and DSC data, the macromolecular additives were partly extracted by isopropyl alcohol as a “good” solvent. The hierarchical nanoporous structure of the obtained gels was demonstrated by the SEM and low-temperature nitrogen adsorption methods. Polymer networks crosslinked with dimethacrylates of ethylene and triethylene glycol contained mostly mesopores, while pores less than 20 nm predominated in the N − vinylpyrrolidone copolymer crosslinked with 1,6 − hexanediol dimethacrylate. It was shown that the values of the specific surface area increased by an order in comparison with conventional polymer networks and reached about 11–16 m2/g.