Adsorption of hydrophobically end-capped poly(ethylene oxide) on poly(tetrafluoroethylene) latex particles: Light scattering study

摘要

The adsorption of an associating polymer, hydrophobically end-capped poly(ethylene oxide) urethane resin (HEUR), on PTFE latex was investigated in aqueous solution by static and dynamic light scattering. A PTFE latex (stabilizer free)/HEUR/water system (probe-polymer interaction system) was compared with a PTFE latex (with stabilizer)/PEO/water system (probe-polymer noninteraction system). Static light scattering studies show that there was no size difference in the PTFE latex (with stabilizer)/PEO/water solution by increasing the PEO concentration, but there was an increase of particle size in the PTFE latex/HEUR/water solution by increase the HEUR concentration. The stabilizer prevents interaction between PTFE and PEO in the PTFE latex (with stabilizer)/PEO/water system, but HEURs are attached on the PTFE particles in the PTFE latex/HEUR/water system. In polarized and depolarized dynamic light scattering studies, a v parameter in "stretched exponential" form of translational diffusion was a sensitive index for showing particle and polymer interaction in the solution, but the parameter of rotational diffusion was not sensitive. The plot of the quotient D-R/D-T vs polymer concentration shows two transitions in the PTFE latex/HEUR/water system. In the PTFE latex (with stabilizer)/PEO/water system, however, the value of D-R/D-T was constant by increasing PEO concentration. On the basis of these experimental data, we suggest three step adsorption mechanisms: molecular adsorption on PTFE particle at low HEUR concentration, C-HEUR < 8 mg/mL; growing of micellar structure at the intermediate concentration, 8 mg/mL < C-HEUR < 15.6 mg/mL; and micellar adsorption after saturation on the PTFE surface at high concentration, C-HEUR > 15.6 mg/mL. [References: 43]