Dynamics in Polydimethylsiloxane: The Effect of Solute Polarity

Abstract

The temperature dependent dynamics of polydimethylsiloxane (PDMS) melts are investigated by measuring orientational relaxation of a dissolved probe molecule, 2-naphthyltriethoxysilane (NTES) using time resolved fluorescence depolarization. The temperature dependent viscosity of PDMS is also reported for two molecular weights. The measurements of nonpolar NTES probe dynamics are compared to previous measurements on the polar probe, N-(triethoxysilylpropy1)dansylamide. The activation energies for the orientational relaxation of the two probes arevery different. This is discussed in terms of the influence of the polarity of the solutes on the local structure in the melts. The results have implications for possible modifications of the physical properties of PDMS materials by using solutes or side groups of varying polarity. The synthesis of the NTES probe, which can also be used as a cross-linking reagent for PDMS, is also described.

ATR-FTIR spectroscopic analysis of sorption of aqueous analytes into polymer coatings used with guided SH-SAW sensors

“…We note that in studies of solute orientational relaxation in PDMS melts, [46] strong intermolecular interaction between a polar solute and the PDMS backbone resulted in significantly larger activation energies for solute reorientation when compared with a nonpolar solute. In addition, the intermolecular interaction was also postulated to perturb the physical properties of PDMS by impeding rotation about the Si-O bond.…”

Effects of Solvent Type on Low-Temperature Sintering of Silver Oxide Paste to Form Electrically Conductive Silver Film

“…Although the relationship between d and swelling is not linear and differs for each solvent system, it is expected that a solvent with d similar to that of PDMS will swell PDMS. [45][46][47][48] This is not surprising considering that solubility is measured by the degree of swelling of materials such as cross-linked polymers that do not dissolve. [43][44][45][46] It was also found that a solvent with high swelling of PDMS showed high solubility.…”

“…[45][46][47][48] This is not surprising considering that solubility is measured by the degree of swelling of materials such as cross-linked polymers that do not dissolve. [43][44][45][46] It was also found that a solvent with high swelling of PDMS showed high solubility. 29 PDMS has a low dipole moment, i.e., low polar properties, 45 so nonpolar solvents such as benzene, pentane, cyclic hydrocarbons, aromatic hydrocarbons, halogenated compounds, and ethers (diethyl ether, dimethoxyethane, tetrahydrofuran) revealed high solubility and high swelling.…”

“…[43][44][45][46] It was also found that a solvent with high swelling of PDMS showed high solubility. 29 PDMS has a low dipole moment, i.e., low polar properties, 45 so nonpolar solvents such as benzene, pentane, cyclic hydrocarbons, aromatic hydrocarbons, halogenated compounds, and ethers (diethyl ether, dimethoxyethane, tetrahydrofuran) revealed high solubility and high swelling. 29 In Table I, the low swelling of the glycols 1-3 may be due to their high polarity.…”

Polystyrene Size Determination in Polystyrene and Poly(vinyl methyl ether) Using Electronic Excitation Transport

“…Here, the experimental approach is the measurement of electronic excitation transport (EET) by observation of time-resolved fluorescence polarization anisotropy, r(t), among naphthalene chromophores attached in low concentration to what are essentially polystyrene chains. This method has been applied to the study of polymer glasses, [1][2][3][4][5] melts, [6][7][8] and blends. 4,8,9 To investigate polymer structure with EET-induced fluorescence depolarization, it is necessary to incorporate fluorophores into the polymer chains.…”