Specific features of the polyelectrolyte behavior of weakly charged cryogels of polyacrylamide and poly(N-isopropylacrylamideстатья
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Дата последнего поиска статьи во внешних источниках: 14 сентября 2013 г.
Аннотация:copolymers of polyacrylamide and poly(Nisopropylacrylamide) with sodium acrylamido2methyl1pro
pyl sulfonate are investigated. The cryogels are synthesized in frozen solutions at –15°C. It is shown that the
polyelectrolyte swelling is significantly weaker in the case of cryogels than that in the case of gels synthesized
in solutions. For thermosensitive gels with isopropylacrylamide groups, collapse occurs during heating.
Charging of a common gel leads to a noticeable (18°C) increase in the transition temperature. For a cryogel,
this growth is 3°C. During the interaction with cetylpyridinium chloride, the gel contraction is much more
pronounced for common weakly charged gels. At the same time, walls of pores of a collapsed cryogel contain
a smaller amount of the solvent. Isotherms of the adsorption of a cationic surfactant by anionic common gels
and cryogels differ insignificantly. Model gels synthesized in concentrated acrylamide solutions exhibit very
weak polyelectrolyte swelling, similar to that of cryogels. The behavior of cryogels is explained by a very high
local concentration of crosslinks due to a strong entanglement of polymer chains.