Dear all,
I´m performing a synthesis of Ge Nps with a hot injection methods carried out at 300°C with the precursor temperature at 280°C.
After the injection and following nucleation, i'd like to replenish the monomer feed stock. The problem is that the monomer fall out of the solution at r.t. , so i need to keep the monomer at high T.
I know about solution transfer with cannnulae, but i don't know how to regulate the flux, and i cannot find a commercial device that provides me such features (high T and controlled flow rate) without being very expensive.
Does anybody have suggestion on the topic?
Best
Bruno.
P.S.
To clarify some unclear part of the post.
This is a hot injection method: 2 precursors in 2 vessel, at high T, one get transferred into the other.
After the transfer, the reaction starts, followed by nucleation and eventually growth. What i want to do is to let the NPs growing bigger, by replenish the monomer feed-stock (which has been consumed by the growing nanoparticles) with a following addition of one of the precursors, at a rate comparable to the rate of consumption during the reaction (3.9 ml/h more or less given the system).
Please refer this article "
High-Temperature Continuous-Flow Zincations of Functionalized Arenes and Heteroarenes Using (Cy2N)2Zn·2LiCl" might be helpful to you
regards
A colleague has done something similar with iron oxide NPs, perhaps these methods might be helpful. If there is a syringe pump in your laboratory that should be the only extra equipment you need. Article Enhanced Nanoparticle Size Control by Extending LaMer's Mechanism
Edit: I see the issue now, the precursor solution needs to be at high T before injection. How high should temperature of precursor solution be (roughly)?
Please refer this article "
High-Temperature Continuous-Flow Zincations of Functionalized Arenes and Heteroarenes Using (Cy2N)2Zn·2LiCl" might be helpful to you
regards
Why can't you keep enough hot so that you don't have to replenish?
Can't you stabilize the suspension in some way? I had the exact same problem once. Got frustrated with the precipitating suspension, put it in the fridge, got back the next day and found out that the suspension had stabilized in the fridge, even after warming to r.t.
(Sorry, cannot say what type of suspension that was, but it might be similar.)
Thanks everybody for the answers!
Dear Neetesh Soni, unfortunately in within the project i'm not able to purchase/build such a nice experimental set-up for continuous flow, but thanks for the suggestion.
Dear Andrew J Mcgrath, indeed a very nice paper! But they're not explicate in the continuous set-up. I enjoyed reading the paper thou.
Dear Victor Granquist, i'm sorry i did not conveyed the message properly, but the need to replenish the monomer feed-stock is because of its depletion along the reaction, not because of the heat. The heat loss happens during the addition of new monomer, since it sits for a long period inside a glass syringe, while being slowly added. From the bright side, yes we're trying to figure out a way to keep the syringe hot enough, namely heating tape.
Dear René Becker, i have not thought about this idea... i'll definitely try it out, but i'm concerned about the possibility of the solvent/capping agent going waxy/solid. Another solution, probably the easiest one, given my hood set-up, will be a cannula transfer, probably under mild vacuum. So instead of a syringe i can keep my precursor in a rb flask and keep it hot on a simple heat pan.
Thanks again for spending time trying to help me.
Best
Bruno
What is the total volume that you need to add?
I'm thinking that you might be able to put a vessel containing the monomer inside of the reaction vessel, so that both solutions are at the same temperature. A syringe pump can then be used to slowly displace the monomer solution from its vessel, by pumping in an inert displacement fluid, either the solvent or another fluid of considerably different density. Mercury would be ideal, at least physically, but a viscous mineral or silicone oil might have a distinct density, and be slow to diffuse. An inert gas might also be effective.
Dear All,
Thanks for all the suggestion.
For those how might be interested, in the end the best flow control with the given equipment, was achieved with a simple over-pressure cannula transfer, just as James Demers suggested.
I just filled a syringe with an inert gas, and connected to the 3 neck containing my precursor, this same 3 neck was connected via cannula to the reaction vessel, while the third central neck was tight closed with a glass lid. the reaction vessel simply connected via cannula to the first one and to a condensation on a Schlenk line, with this even if there is a bit of lag time from the pump activation, and kind of a fluctuation in the flow rate, i was able to go close to my intended flow rate.
Thanks everybody for the interest
Best
Bruno
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