Patent ID: 9624319
Date: 2017-04-18
CPC Classifications: C08F

Claim:
1. A method to prepare a fluorinated polymer having perfluoromethyl terminal groups, comprising: heating a fluorinated polymer at from 200 to 400° C. for at least one hour in the presence of molecular oxygen to convert from 50 to 100 mol % of terminal groups comprising units of a polymerization initiator, a chain transfer agent or a dispersion stabilizer to carboxylic acid fluoride groups (—COF); and reacting molecular fluorine with the fluorinated polymer comprising the carboxylic acid fluoride groups to convert the carboxylic acid fluoride groups to perfluoromethyl groups; wherein in the reaction of molecular fluorine with the fluorinated polymer comprising the carboxylic acid fluoride groups the fluorine gas is dissolved and reacted in a solution of the fluorinated polymer having the carboxylic acid fluoride groups, and a mol ratio of molecular oxygen to terminal groups comprising units of a polymerization initiator, a chain transfer agent or a dispersion stabilizer is at least 50/1.