I would like to apprecieate your comments, i updated this post with more details
In this work i have to do local polymerization in a micro channel the heigth of micro channel is 12um and the size of mask is 80*160um. the monomer solution is 2M APMSA, 2% CL, 2%PI, 100ppm HQ,
the PI has high absorbance in 270nm and due to some issue currently i am using 35nm LED for curing.
First i fill the channel with monomor then exposing under uv 365nm and after that scuktion of all remain monmer and washing channel as you see in the photo is 30s the monomer is cured well but it spreaded out while in the 29 sec the center is not cured well ... this transition is so fast and hard to control.
AMPSA: 2-Acrylamido-2-methyl-1-propanesulfonic acid
http://www.sigmaaldrich.com/catalog/product/aldrich/282731?lang=ko®ion=KR
PI : 2-Hydroxy-4′-(2-hydroxyethoxy)-2-methylpropiophenone
http://www.sigmaaldrich.com/catalog/product/aldrich/410896?lang=ko®ion=KR
HQ : Hydroquinone
http://www.sigmaaldrich.com/catalog/product/sial/h9003?lang=ko®ion=KR
CL: N,N′-Methylenebis(acrylamide)
http://www.sigmaaldrich.com/catalog/product/sial/146072?lang=ko®ion=KR
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In my experiment I need to polymerize inside micro-channel and the problem I have is the center of polymer is not cured well and the polymer is not dense. Is there any person who had same problem before?
The attachment photos (right side) shows the non-cured area after drying.
Dear Ali;
generally speaking this is due to the low thermal conductivity of the polymeric matrix. In fact you have a gradient of crosslink density; increasing from the center to the outer shell. In this situation radiation curing is more suitable. You did not mentioned how thick is this item. Regards
What kind of polymerization are you doing. For radiation cure of acrylate and methacrylate monomers I know of at least two factors that may adversely impact depth of cure. The first is related to the kinetics. Reaction rate increases with temperature to a point and then begins to decrease above a given temperature (I think around 60 to 70 degrees C). This may be related to Abdelkader's comments above. If a photoinitiator is being used dose is reduced as the PI absorbs some of the radiation.
Very likely there are movements/diffusion of your monomers and/or solvents during the polymerization, caused by the difference in the curing rate. You can try to increase the monomer concentration, initiator content or light intensity (if you're doing photo-curing), to see if you can get more uniform polymers inside the micro-channel. Again, you can introduce a little bit details of your formulation and polymerization technique you're doing, so that people could help you better.
Dear all, Abdelkader, Michael, David, Qiang, Harith,
I would like to appreciate your kind attention, I updated my post with more information please check it out.
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