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| Materials and method for the detection and treatment of Wegener's granulomatosis |
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Perfluorocyclobutane ring-containing polymers
| Details |
Inventors: Babb, David A.; Richey, W. Frank; Clement, Katherine S.; Ezzell, Bobby R.;
Assignee: The Dow Chemical Company (Midland, MI)
Primary Examiner: Szekely; Peter
Assistant Examiner:
Attorney, Agent or Firm:
A process for preparing a polymer having perfluorocyclobutane rings by the steps of (a) contacting monomers having aromatic polyester, aromatic polyamide, or polyimide groups or combination thereof, at least two dimerizable perfluorovinyl groups; and (b) exposing the monomers to sufficient heat and for a sufficient time that a polymer containing perfluorocyclobutane rings is formed. Chain extending oligomers of polymers having poor processing characteristics by this process results in polymers which are more easily processed. For instance, perfluorocyclobutane groups formed in an extruder to chain lengthen polyimide oligomers, in effect, render polyimides extrudable. The polymer formed by the method preferably has polyimide groups. New monomers and polymers having imide and perfluorovinyl or perfluorocyclobutane structures, respectively, are prepared. |
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DETAILED DESCRIPTION OF THE INVENTION Polymers of the invention are formed by thermal reaction of monomers having at least two dimerizable perfluorovinyl groups such that perfluorocyclobutane groups are formed.
A dimerizable perfluorovinyl group is a perfluorovinyl group which reacts with another such group to form a perfluorocyclobutane ring.
Thus, resulting polymers have at least two perfluorocyclobutane groups, in particular sufficient perfluorocyclobutane groups to achieve physical and electrical properties desired for specific uses of the polymers.
The term polymer is used herein to refer to any compound having at least two perfluorocyclobutane groups formed from perfluorovinyl groups, and includes oligomers which have from about 2 to about 100 repeating units and preferably have a weight average molecular weight of from about 300 to about 30,000.
It is within the scope of the present invention to form lower weight average molecular weight oligomers useful as fluids or prepolymers and higher weight average molecular weight polymers exhibiting general plastic properties.
Within this scope and depending on the molecular structure connecting the perfluorocyclobutyl groups, the number of perfluorocyclobutane groups can vary from as few as two up to thousands.
The process of forming polymers or oligomers by the process of the present invention is general and capable of forming products having wide ranges of utility.
Physical and electrical properties of the resulting products are highly dependent on the choice of the molecular structure between the perfluorocyclobutane groups as well as the number of perfluorocyclobutane groups.
The relative proportion by weight of the perfluorocyclobutane groups to the other molecular components of the resulting products can vary over a wide range of from about 12 to 1 to about 0.
01 to 1, preferably from about 5 to 1 to about 0.
02 to 1 and most preferably from about 2 to 1 to about 0.
03 to 1.
High proportions of perfluorocyclobutane groups are desirable for instance, when fluorocarbon character such as low dielectric constant is beneficial in the products
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