Experimental
General. Kel - F 6061 was provided by 3M corporation. Neoflon
M400H was provided by Daikin corporation. All other reagents were
purchased from Aldrich Chemical company and used as received.
IR spectra were recorded using a Perkin Elmer 1600 FT - IR
spectrometer. ATR - IR spectra were collected with a Perkin Elmer
Spectrum 2000 FT - IR spectrometer interfaced to a Harrick Split -
pea attenuated total internal reflection (ATR) microscope. Scanning
electron micrographs were obtained on a Philips 505 SEM spectrometer.
Combustion analyses were performed by Galbraith Laboratories,
Inc.
Preparation of PCTFE - CO2H
PCTFE (1.04 g, 8.6 meq), 3.04 g (13.8 mmol) Cr(CO)6, and 2 ml of
water were suspended in 50 ml DMF under nitrogen. The resulting
slurry was stirred at 90 oC for four days. Sublimed metal carbonyl
reagent was washed back into the reaction flask by small amount of
DMF. The green slurry was filtered and washed sequentially with
hexane, acetone, methanol, water and methanol again. The dark brown
product was purified using Soxhlet extraction. The resulting product
was dried in an Abderhalden apparatus with refluxing toluene and
reduced pressure. The product was further characterized using
titrimetric analysis.
IR (KBr) 3490 (br), 1680, 1400, 1358, 1278, 1200, 1125, 970 cm
-1. Titrimetric analysis: 0.392
meq/g ion exchange capacity for Kel - F and 0.239 meq/g for
Neoflon.
Procedure for titrimetric analysis
A slurry of polymeric acid and 3M HCl was stirred at approximately 80
oC for 3 hours. The resin was filtered on a Buchner funnel and washed
with distilled water. This sequence was repeated twice. The sample
was then dried in an Abderhalden apparatus with refluxing toluene and
reduced pressure overnight. The sample was then titrated as follows:
In a mixture of 0.5 g of acid and 0.5 g NaCl was added 10 ml
distilled water and 3 - 5 ml of methanol. The reaction mixture was
stoppered and sonicated overnight. Phenolphthalein (3 - 5 drops) was
added to this mixture and titrated against 0.04 M standardized NaOH
solution. Ion exchange capacity was determined to be 0.39 meq / g for
modified Kel - F and 0.239 meq / g for modified Neoflon.