| 摘要 |
<p>A perfluoropolyether of general formula: A-(OC3F6)m-¢OCF(CF3)!n-(OCF2)p-(OC2F4)r-O-B wherein: m, n, p and r are zero or an integer of from one to 50, with the proviso that m+n+p+r is at least 2; and A and B, independently, represent an end group selected from -CF2X, -CF2CF2X, -CFX(CF3), -CF2CFX(CF3), -C(O)F, -CF2C(O)F and -C(CF3)C(O)F, wherein X represents a group selected from F and Br, with the proviso that at least one of A or B contains a Br; wherein the perfluorooxyalkylene units are randomly distributed along the perfluoropolyether chain. A process for preparing the perfluoropolyether, comprising: photolysing, with UV radiation, the product obtained from the photochemical oxidation of a group selected from -C2F4-, -C3F6- and a mixture thereof in the presence of bromine at a temperature in the range of from -40 to 130.degree.C, wherein the bromine concentration is such as to saturate the liquid reaction medium. The process of the present invention provides the above described products which have a controlled molecular weight.</p> |
