Adsorption Kinetics of cis-1,4-Polyisoprene in Nanopores by In Situ Nanodielectric Spectroscopy

Abstract

Using in situ nanodielectric spectroscopy, we studied the adsorption kinetics of cis-1,4-polyisoprene (PI) into porous alumina by following the evolution of the dielectrically active longest normal mode. We studied the influence of molar mass, nanopore diameter, and surface functionalization. Adsorption times depend strongly on the ratio 2R g/D, where R g is the radius is gyration and D is the pore diameter. For a given pore diameter, the characteristic adsorption times are some 8 orders of magnitude slower than the terminal relaxation times and more than 12 orders of magnitude slower than the segmental times. The extremely slow kinetics reflect the fact that exchanging chains with the pore surface have to pass through several unfavorable configurations (e.g., trains, loops). The molar mass dependence of the characteristic adsorption times (τads ∼ N 2.6) is in good agreement with a scaling theory proposed by de Gennes and later refined by Semenov and Joanny. Subsequently, we investigated the imbibition of miscible PI blends by taking advantage of the difference in imbibition speeds of the respective homopolymers. We show that the shorter chains penetrate first the nanopores, whereas the longer chains enter only at the late stages of the filling process. Moreover, the long-time adsorption is dominated by an exchange mechanism involving primarily the shorter chains. The results from in situ nanodielectric spectroscopy demonstrate the capacity of the technique to provide the imbibition length, the adsorption kinetics, and, at the same time, the chain dynamics.

Effect of the Surface Polarity, Through Employing Nonpolar Spacer Groups, on the Glass-Transition Dynamics of Poly(phenyl methylsiloxane) Confined in Alumina Nanopores

“…Interestingly, it can even completely reverse the trend due to increasing adsorption. As a result, the dielectric loss curves start to decrease in intensity with time. , …”

“…As a result, the dielectric loss curves start to decrease in intensity with time. 67,68 Analysis of the Dielectric Permittivity for the Polymer Confined in Alumina Nanopores. Herein, it should be noted that the nanopore-confined system under consideration is an inhomogeneous dielectric that includes the tested polymer located inside the alumina matrix.…”

Adsorption Kinetics of Polystyrene and Poly(9-anthracenyl methyl methacrylate) onto SiO2 Surface Measured by Chip Nano-Calorimetry

“…This may have resulted from the difference in the chemical structure of the substrate; the SiO 2 surface was used in our experiment, and Al 2 O 3 was used in the dielectric spectroscopy reported by Napolitano et al These differences in the chemical structure of the substrate may affect the adsorption kinetics. The effect of polymer/substrate interaction on the polymer adsorption kinetics has been discussed by other groups [ 24 , 34 , 35 ]. It has been revealed that the adsorption rate is reduced when the polymer/substrate interaction becomes strong.…”

“…We followed the established protocol using the Guiselin approach [ 32 , 33 , 34 , 35 ] for PAMMA-adsorbed layers ( Figure 2 ). Optically polished SiO 2 (2 cm × 2 cm) substrates were cleaned using the following procedure.…”

Effect of Star Architecture on the Dynamics of 1,4-cis-Polyisoprene under Nanometer Confinement

“…7,[10][11][12][13][14]20 Recent results by in situ nanodielectric spectroscopy on a type-A polymer, cis-1,4-polyisoprene (PI), revealed stronger changes in the chain dynamics in comparison to the local segmental dynamics as a result of chain adsorption during PI imbibition in nanopores. 21,22 The reason being that the adsorption of even few segments in a chain will bring about a reduction in the dielectric strength of the normal modes (NMs) (the part of the chain between the adsorbed segments is unable to fluctuate and thus does not contribute to the dielectric strength). Moreover, even the adsorption of a single segment will affect the chain dynamics but will exert a smaller influence on the segmental dynamics.…”