TY - JOUR
T1 - Formation of water-free cavity in the process of nafion swelling in a cell of limited volume; effect of polymer fibers unwinding
AU - Ninham, Barry W.
AU - Bolotskova, Polina N.
AU - Gudkov, Sergey V.
AU - Juraev, Yulchi
AU - Kiryanova, Mariya S.
AU - Kozlov, Valeriy A.
AU - Safronenkov, Roman S.
AU - Shkirin, Alexey V.
AU - Uspenskaya, Elena V.
AU - Bunkin, Nikolai F.
N1 - Publisher Copyright:
© 2020 by the authors. Licensee MDPI, Basel, Switzerland.
PY - 2020/12
Y1 - 2020/12
N2 - When Nafion swells in water, colloidal particles are repelled from the polymer surface; this effect is called the formation exclusion zone (EZ), and the EZ size amounts to several hundred microns. However, still no one has investigated the EZ formation in a cell whose dimension is close to the EZ size. It was also shown that, upon swelling in water, Nafion fibers “unwind” into the water bulk. In the case of a cell of limited volume, unwound fibers abut against the cell windows, and water is completely pushed out from the region between the polymer and the cell window, resulting in a cavity appearance. The temporal dynamics of the collapse of this cavity was studied depending on the cell size. It is shown that the cavity formation occurs due to long-range forces between polymer strands. It turned out that this scenario depends on the isotopic composition of the water, ionic additives and water pretreatment. The role of nanobubbles in the formation and collapse of the cavity were analyzed. The results obtained allowed us to conclude that the EZ formation is precisely due to the unwinding of polymer fibers into the liquid bulk.
AB - When Nafion swells in water, colloidal particles are repelled from the polymer surface; this effect is called the formation exclusion zone (EZ), and the EZ size amounts to several hundred microns. However, still no one has investigated the EZ formation in a cell whose dimension is close to the EZ size. It was also shown that, upon swelling in water, Nafion fibers “unwind” into the water bulk. In the case of a cell of limited volume, unwound fibers abut against the cell windows, and water is completely pushed out from the region between the polymer and the cell window, resulting in a cavity appearance. The temporal dynamics of the collapse of this cavity was studied depending on the cell size. It is shown that the cavity formation occurs due to long-range forces between polymer strands. It turned out that this scenario depends on the isotopic composition of the water, ionic additives and water pretreatment. The role of nanobubbles in the formation and collapse of the cavity were analyzed. The results obtained allowed us to conclude that the EZ formation is precisely due to the unwinding of polymer fibers into the liquid bulk.
KW - Deuterium-depleted water
KW - Fourier transform IR spectroscopy
KW - Nafion
KW - Swelling of polymers
KW - Wetting angle
UR - http://www.scopus.com/inward/record.url?scp=85097103711&partnerID=8YFLogxK
U2 - 10.3390/polym12122888
DO - 10.3390/polym12122888
M3 - Article
SN - 2073-4360
VL - 12
SP - 1
EP - 18
JO - Polymers
JF - Polymers
IS - 12
M1 - 2888
ER -