Dynamic light scattering from swollen poly(dimethylsiloxane) networks

Abstract

Poly(dimethylsi1oxane) (PDMS) networks which contain various amounte of pendant chains are prepared by end-linking mixtures of difunctional PDMS (Bz), monofunctional PDMS (Bl), and a tetrafunctional cross-linker (&). Dynamic light-scattering (DLS) experimente are performed on the tolueneswollen networks and on PDMWtoluene solutions. The magnitude of the scaling exponents of the cooperative diffusion coefficient versus the equilibrium concentration in swollen networks and versus concentration in solutions are in good agreement with Freed and Edwards' ideal chain predictions assuming no excluded volume in the length scale of the hydrodynamic correlation length FH. The ratio of the diffusion coefficientin a network to that in solution of equal concentration, Dmmor~Dlo~u~on, appears to be constant and is found to be 1.45 i 0.14, in good agreement with the estimate of 1.5 obtained on the basis of the Flory-Rehner expression.

End-Linked Poly(dimethylsiloxane) Elastomers: 2H-Nuclear Magnetic Resonance Investigations of Compression-Induced Segment Anisotropy

“…These networks are well characterized; mechanical and swelling properties, light scattering from swollen samples of similar networks, and 2 H-NMR of unconstrained samples have been reported previously. [14][15][16][17] Background 2 H-NMR is sensitive to elastomer segment anisotropy through the orientation-dependent quadrupolar interaction. In PDMS(d) the NMR frequency shift caused by the quadrupolar interaction, ν Q , reflects the timeaveraged orientation of a C-2 H bond:…”

Temperature‐Driven Switching of Water Adhesion on Organogel Surface

“…During the immersion, PDMS was swollen, that is, due to the affi nity of paraffi n to PDMS, a certain amount of paraffi n was impregnated into the crosslinked network of PDMS gel. [ 13 ] In order to reach swelling equilibrium, the PDMS cubes were soaked for at least 4 h. (Detailed investigation on this swelling property is seen in Figure S1.) Consequently,…”

Front Matter: Volume 8340

“…The mechanical properties of polymer networks may be tuned by changing the molecular weight of the polymer chains and by varying the stoichiometric imbalance given by the molar ratio between the reactive groups of the crosslinker and the vinyl groups of the PDMS [8][9][10][11][12][13] :…”