Fluorine-containing surface treatment agent and an article treated with the same

A surface treatment agent comprising a fluorooxyalkylene group-containing polymer composition, wherein the composition comprises

• a fluorooxyalkylene group-containing polymer having
• a fluorooxyalkylene structure represented by —(OCF2)p(OCF2CF2)q−;
• wherein p and q are, independently of each other, an integer of from 5 to 80 and a total of p and q is 10 to 100, and these parenthesized units may be sequenced at random;
• and
• at least one group represented by the following formula (1) at at least one terminal;
• wherein R is an alkyl group having 1 to 4 carbon atoms or a phenyl group, X is a hydrolysable group, a is 2 or 3, and c is an integer of from 1 to 10;
• and/or
• a product obtained by partial hydrolysis and condensation of said polymer;
• and
• an another polymer represented by the following formula (3):
• A-Rf-A (3)
• wherein Rf is —(CF2)d—(OCF2)p(OCF2CF2)q(OCF2CF2CF2)r(OCF2CF2CF2CF2)s—O(CF2)d−, d is an integer of from 0 to 5, p and q are, independently of each other, an integer of from 5 to 80, r and s are, independently of each other, an integer of from 0 to 80, and a total of p, q, r and s is 10 to 100, A is a fluorine atom, a hydrogen atom, or a monovalent fluorinated group having a —CF3 group or a —CF2H group at a terminal, and these parenthesized units may be sequenced at random,
• and shows a decrease of 75% or more in weight, relative to the total weight of the polymer composition, in a temperature range of from 150 to 350 degrees C. when heated at a rate of 2 degrees C. per minute and a pressure of 0.1 Pa or less.