[Swan]

Hello,

I’d like to form small “microcapsules” of glycerol in a paraffinic mineral oil but am struggling so far.

My initial approach has simply been to form an emulsion (by stirring and using a commercial w/o surfactant); subsequently heat the emulsion and add various anhydrides (e.g. phthalic) to form polyester at interface of the glycerol “droplets”. However, this seems to require a higher temperature (>200°C) than the oil can withstand, at least without catalyst.

So, I’m thinking of suitable monomers which could be solved in the glycerol and/or the oil to form a polymer at the interface of the droplets. A couple of requirements are:

- The temperature should not be higher than 200°C to avoid oxidation of the oil

- The polymer shell should preferably be hydrophobic to avoid agglomeration of the microcapsules. (Would it be possible to use a surfactant as a monomer?)

Any suggestion would be appreciated.

Regards,
/Swan

[P]

Are you trying to initiate the polymerisation with temperature? Could you use some kind of initiator which would initiate the polymerisation at a much lower temperature?

With suspension/emulsion polymerisations vigorous mixing is important (with a suitable surfactant as you suggested) to stop the agglomeration of the particles. A flask with baffles in it helps allot with this I have found.   

Regards,

P.

[Swan]

Yes the mixture is continuously agitated throughout the process.

Are you trying to initiate the polymerisation with temperature? Could you use some kind of initiator which would initiate the polymerisation at a much lower temperature?

Well, it doesn't necessarily have to be initiated by temperature. If reaction would occur at room temperature I guess it would be easy to add one of the components once the emulsion have formed, without heating.

A wild example with epoxy:
Solve e.g. BADGE in the glycerol, form an emulsion of glycerol with dissolved BADGE in mineral oil using a surfactant and stirring. Then add e.g. a triamine to the mixture (the oil phase) and heat it. Could it work?

/Swan

[P]

Thats the idea.  I do not know about your system or if the BADGE will polymerise it or not, but with styrene polymerisation, for another wild example, you can get it to polymerise at 40C (aprox) by adding some free radical initiator like BPO or AIBN.   You'll have to look up what you can use to get lower temp polymerisation of your stuff.

- The polymer shell should preferably be hydrophobic to avoid agglomeration of the microcapsules. (Would it be possible to use a surfactant as a monomer?)

Just a thought on this  -  if the surface of your particles were hydrophobic (not liking the water) then surley they would clump together even more?  If they are hydrophobic, they will clump to get into contact with each other in preference to the water (or am I missing something here)?   Perhaps I'm getting confused  - is the suspension in water or oil?  Anyway - yes - the surfactants should help alot with this.

[Swan]

Thank you for your suggestions P!

Thats the idea.  I do not know about your system or if the BADGE will polymerise it or not, but with styrene polymerisation, for another wild example, you can get it to polymerise at 40C (aprox) by adding some free radical initiator like BPO or AIBN.   You'll have to look up what you can use to get lower temp polymerisation of your stuff.

Yes, styrene could be an option - but would the polymer form at the glycerol/oil-interface? Maybe if one could solve a radical initiator in the glycerol? I guess I'll have to check that up.

Just a thought on this  -  if the surface of your particles were hydrophobic (not liking the water) then surley they would clump together even more?  If they are hydrophobic, they will clump to get into contact with each other in preference to the water (or am I missing something here)?   Perhaps I'm getting confused  - is the suspension in water or oil?  Anyway - yes - the surfactants should help alot with this.

The suspension is in non-polar mineral oil, i.e. w/o emulsion. It could also be possible to add a surfactant after polymerization to disperse the microcapsules.

/Swan

[Swan]

Just noted that this thread should probably be in organic chemistry. Sorry, my mistake. Is it possible to transfer it?

/Swan