Fluorinated thermoset polyurethane elastomers prepared from polyether coprepolymers formed from mono-substituted fluorinated oxetane monomers and tetrahydrofuran

• US 5,703,194 A
• Filed: 06/07/1995
• Issued: 12/30/1997
• Est. Priority Date: 07/10/1992
• Status: Expired due to Fees

• Current Assignee: Aerojet-General Corporation (L3Harris Technologies, Inc.)
• Original Assignee: Aerojet-General Corporation (L3Harris Technologies, Inc.)
• Inventors: Archibald, Thomas G., Malik, Aslam A.
• Primary Examiner(s): WILSON, DONALD R
• Application Number:
  US08/483,220
• Time in Patent Office: 937 Days
• Field of Search: 528/70, 528/402, 568/615, 568/617, 549/511
• US Class Current: 528/70
• CPC Class Codes: C07D 305/06 with only hydrogen atoms, hydrocarbon or substituted hydrocarbon radicals, directly attached to the ring atoms
• CPC Class Codes: C08G 18/10 Prepolymer processes involving reaction of isocyanates or isothiocyanates with compounds having active hydrogen in a first reaction step
• CPC Class Codes: C08G 18/32 Polyhydroxy compounds; Polyamines; Hydroxyamines
• CPC Class Codes: C08G 18/5015 having fluorine atoms
• CPC Class Codes: C08G 18/6677 having at least three hydroxy groups
• CPC Class Codes: C08G 65/00 Macromolecular compounds obtained by reactions forming an ether link in the main chain of the macromolecule
• CPC Class Codes: C08G 65/18 Oxetanes
• CPC Class Codes: C08G 65/20 Tetrahydrofuran
• CPC Class Codes: C08G 65/226 containing fluorine

Abstract

This application is directed to novel fluorinated polymers and prepolymers derived from mono-substituted oxetane monomers having fluorinated alkoxymethylene side-chains and the method of making these compositions. The mono-substituted fluorinated oxetane monomers having fluorinated alkoxymethylene side-chains are prepared in high yield by the reaction of a fluorinated alkoxides with either 3-halomethyl-3-methyloxetane premonomers or aryl sulfonate derivative of 3-hydroxymethyl-3-methyloxetane premonomers. Preparation of a mono-substituted 3-bromomethyl-3-methyloxetane premonomer via a simple, high yield process amenable to commercial scaleup is also disclosed. The fluorinated oxetane monomers of this invention can be readily homo/co-polymerized in the presence of a Lewis acid and polyhydroxy compounds to obtain hydroxy-terminated polyether prepolymers having fluorinated alkoxymethylene side chains. Additionally, the fluorinated oxetane monomers can be copolymerized with non-fluorinated monomers such as tetrahydrofuran to give polyether prepolymers with improved hydrocarbon compatibility. These prepolymers are polydisperse and exhibit number average molecular weights from 5,000 to about 50,000. These prepolymers are amorphous oils with primary hydroxy end-groups and thus function efficiently as the soft block for the synthesis of a variety of thermoset/thermoplastic elastomers and plastics having the characteristics of very low surface energy, high hydrophobicity, low glasss transition temperature and low coefficient of friction. The polyurethanes derived from the prepolymers of this invention are elastomeric and, in addition to the above characteristics, exhibit high moisture resistance, high tear strength and excellent adhesion to a variety of substrates.

Claims

1. A fluorinated thermoset polyurethane elastomer having random FOX/THF segments and having the structure, ##STR14## where:

a) n is 1-3;

b) R is selected from the group consisting of methyl and ethyl;

c) R_f is selected from the group consisting of linear and branched perfluorinated alkyls having 1-20 carbons, and oxaperfluorinated polyethers having from about 4-20 carbons;

d) R¹ is a divalent hydrocarbyl radical;

e) X is 1-20;

f) Y is 10-150;

g) Z is 2-50.

2. A fluorinated thermoset polyurethane elastomer as in claim 1 wherein said isocyanate segments are selected from the group consisting of hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), 4,4'"'"'-methylene diphenylisocyanate (MDI), polymeric MDI, toluene diisocyanates, hydrogenated MDI (HMDI), polymeric HDI, trimethylhexane diisocyanate and mixtures thereof.

3. A fluorinated thermoset polyurethane elastomer as in claim 2 wherein said fluorinated polyether segment is produced from at least one monomer selected from the group consisting of 3-(2,2,3,3,4,4,5-heptafluorobutoxymethyl)-3-methyloxetane, 3-(2,2,2-trifluoroethoxymethyl)-3-methyloxetane, 3-(3,3,4,4,5,5,6,6,7,7,8,8,8-tridecafluorooctyloxymethyl)-3-methyloxetane, 3-(3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,10-heptadecafluorooctyloxymethyl(-3-methyloxetane, and 3-(3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,11,11,12,12,12-heneicosafluorododecyloxymethyl)-3-methyloxetane.