Hello all together,
during the course of a project, I observed a strange interaction which I cannot explain. When I blended an anionic PUD (pH 7) with my anionic acrylat emulsion (also pH 7), a gelling set in over time. This effect was of course accelerated at 40 °C and 50 °C respectivly, leading to a solid gel after 1 day. Blending tests with different acrylic emulsions revealed that the acid number, i.e. concentration of neutralized carboxylic acids , is directly corelated with the speed of the gelling (with a pure polycarboxylate it gels upon addition). If I decrease the acid number of my acrylic emulsion under a certain value, the mixture stays stable, also at 50 °C. Nevertheless, I have to understand the mechanism. It has to be a kind of hydrogen-bonding or polar interaction betwenn the carbamates/urea links in the PUD and the carboxylates. However, I could not find literatur about that process. Has anybody experienced something similar, knwoledge about the mechanism or a reasonable suggestion for a mechanism?
Greetings to all my former colleagues.
Thanks in advance.
Dear Kim K Oehlenschlaeger, besides showing high miscibility, this couple of polymers have high tendency to form an interpenetrating networks. If it is the case secondary interaction effect is only secondary, more contribution to gel character is due to unlocked knots formed betwenn them. My Regards
Hi;
The formation of the solid gel confirms that a semi-IPN or IPN polymer network has been obtained.
With my best regards
Hi Abdelkader and Doufnoune, thanks a lot for your awnsers. I'm also convinced that some kind of network is formed due to the interactions of the two polymers.
However my question would be which kind of interaction is it or to put it more simple, why/how are these knots formed. Which kind of bonding takes place between the two polymers. Do you have an idea or experience in this field? Thanks in advance.
Dear all, if you mean secondary intermolecular interactions, H-bonding is the most dominant one. My Regards
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