how to synthesize highmeolecualr weight polyurethane by using IPDI and polyesrer based polyol taking IPA as solvent by solution process.
IPA? isopropyl alcohol you mean?
You are limited to solvents that do not react with NCO. Often ketones, NEP or NMP is used. When you really want to go to a high molecular weight polyurethane, better dry your solvents to avoid water and thus forming urea and leaving parts of the polyester unreacted, influencing the desired structure and MW.
When the NCO conversion if 100% (read: your polymer ready) you may add OH-solvents and when possible remove the ketones by distillation.
Mr. Roelofs,
Yes, I mean isoproply alcohol.Only drying of solvent take care of molecular weight or some special technique to be adopted to reach the molecular weight. Actulally i am targeting around 60000 Mw.
During you polyurethane synthesis you cannot use IPA, it works as a chain chopper, you will end with very low MW's. AFTER the PUR synthesis you may add IPA.
Agreed ! But, herewith an attached publication where IPA used as solvent for synthesis.
Article Preparation of segmented, high molecular weight, aliphatic p...
You are referring to NCO/amine reactions, to form polyureas. That's different from OH/NCO reactions, with lead to polyurethanes, and your question was concerning polyurethanes, not ureas.....
I think you better use NMP or DMF as a solvent for polyurethane synthesis. Polyol and solvent should be moisture-free in order to minimize water - NCO reaction which leads to consumption of NCO and formation of carbamic acid (which becomes amine with CO2). For high MW, chain extension is recommended. In the case of solution polymerization, diols will be better in the presence of catalysts (TEA or DBTDL). Primary amines like EDA will give you crosslinked PU. For further details, please send me e-mail.
As the other person said, IPA has only one OH, therefore it is not suitable for PU synthesis.
Mono ol will limit the polymerization in producing high mw PU...better choose multifunctional
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