RWTH Aachen University
Question
Asked 19th Jun, 2019
A hydroxyl group terminated polymer reacts with an isocyanate silane, will the -OH groups react with -Si(OR)3 groups?
The isocyanate silane is a small molecule with the -NCO group on one end and the -Si(OR)3 group on the other end. The -OH terminated polymer is dissolved in ethyl acetate that is <100 ppm water content. When this isocyanate silane compound is added into the polymer solution, will the -Si(OR)3 group react with the -OH of the polymer backbone?
Most recent answer
They will react but much slower than the desired NCO-OH reaction to urethane. The NCO-OH reaction will predominate.
All Answers (4)
George Mason University
It is unlikely, usually silyl chlorides are needed to react with OH and even then you need some sort of active nitrogenous like pyridine, DMAP, or imidazole to form an activated silinium cation.
Plus the more bulky your R groups on the Si, the more unreactive it becomes.
1 Recommendation
Semenov Institute of Chemical Physics
Yes, it certainly will react, but formation of small amount of by-products is inevitable.
Similar questions and discussions
What is the purpose of adding isopropanol in back titration of isocyanate with dibutylamine?
A standard way to measure isocyanate (NCO) content in polymer is to first react with dibutylamine then back titrate the unreacted base with a strong acid. My Standard of Procedures says to dissolve sample in toluene, add dibutylamine, add isopropanol then back-titrate. What is the purpose of using isopropanol?
EDIT 1: See https://www.kyoto-kem.com/en/pdf/industry/PlasticRubber/ETII-98003.pdf for a procedure similar to the one I'm using. I am looking for the purpose of isopropanol present in large quantities, when there's already a solvent for the sample, a reagent in excess, for which there is also a (back-)titrant.
Recommendations
Typescript. Thesis (M.S.)--New Jersey Institute of Technology, 1982. "References": leaves 218-219.
For the manufacture of composites with improved resilience-strength and performance properties hydroxyl containing arylaliphatic mixtures of industrial epoxy oligomers or unsaturated polyester oligomers (on the basis of diphenylolpropane /DGEBA/, Laprol /carboxilated oxypropylene-triol/ and polyepichlorohydrin) and modified within di-or triisocyana...
Partial substitution of polymeric methylene diphenyl diisocyanate resin with soy flour increases the cold tack of the resin to the level achieved by urea formaldehyde resin. The tack can be fine-tuned by adjusting the amount of soy flour added. The increase in tack is caused by the reaction of the isocyanate resin with the water contained in soy fl...