A cyclic carbodiimide compound which is useful as an end-sealing agent for polymer compounds. The cyclic carbodiimide compound is represented by the following formula (i):
In the above formula, X is a divalent group or a tetravalent group represented by the following formula (i-4). When X is divalent, q is 0 and when X is tetravalent, q is 1. Ar
1
to Ar
4
are each independently an aromatic group. They may be substituted by an alkyl group having 1 to 6 carbon atoms or phenyl group.
Disclosed is a cyclic carbodiimide compound useful as an end-capping agent for polymer compounds. The cyclic carbodiimide compound is represented by the following formula (i):
wherein X is a specific divalent group or tetravalent group, q is 0 when X is a divalent group, while q is 1 when X is a tetravalent group, and Ar
1
to Ar
4
are selected from aromatic groups each independently optionally substituted with a group that serves as X.
Highly aromatic polyurea/urethane membranes and their use for separating aromatics from non-aromatics
申请人:EXXON RESEARCH AND ENGINEERING COMPANY
公开号:EP0312374A2
公开(公告)日:1989-04-19
Novel membranes, useful for the separation of aromatics from mixtures thereof with non-aromatics, in, for example, a naphtha feed stream, are characterized by possessing a urea index of at least about 20% but less than 100%, an aromatic carbon content of at least about 15 mole percent, a functional group density of at least about 10 per 1000 grams of polymer and a C = O/NH ratio of less than about 8.0. These highly aromatic polyurea/urethane membranes are symmetric, dense film membranes made from the corresponding polyurea/urethane copolymers by standard membrane casting techniques. The polyurea/urethane copolymers are preferably produced by reacting dihydroxy or polyhydroxy compounds, such as polyethers or polyesters having molecular weights in the range of about 500 to 5000 with aliphatic, alkylaromatic or aromatic diisocyanates or polyisocyanates and low molecular weight chain extenders, such as diamines, polyamines or amino alcohols.
The membranes are useful for separating aromatics from non-aromatics in e.g., petroleum refining and chemical applications.
Medical devices having a coating of amine rich fluorinated polyurethaneurea and an antithrombogenic agent covalently bonded thereto and method for their preparation
申请人:Becton Dickinson and Company
公开号:EP0404515A2
公开(公告)日:1990-12-27
A thermoplastic polyurethaneurea having free amino groups and comprising a product from the reaction of a diisocyanate, a polyamine and a misture of polyols comprising a fluorinated polyol and a non-fluorinated polyol selected from polyalkyleneoxide polyols and polyester polyols. A medical device having a hemocompatible surface comprising a shaped polymeric article having thereon a coating of a thermoplastic polyurethaneurea as claimed in Claim 1, and an antithrombogenic agent covalently affixed to amino groups of the polyurethaneurea coating.
A melt extruded cathether of thermoplastic elastomeric hydrophilic polyurethane synthesized from a diisocyanate, a polyglycol component comprising a polyethyleneoxide glycol of high molecular weight and a chain extender expands to a larger lumen size when contacted with an aqueous liquid. The catheter may include an antithrombogenic agent, antiinfective agent and radiopaque agent. The hydrophilic polyurethane may be synthesized by one-shot bulk polymerization, and may be melt extruded into the catheter tubing, and may encapsulate a stripe of a stiffening polyurethane.