Amount of catalyst varies with the requirement of molecular weight or speed of reaction. For molecularly imprinting polymer the polymer is heavily crosslinked. Anount of catalyst needed is about 2 mol% for getting crosslinked solid MIP

In addition to the speed and desired molecular weight mentioned in the first response, the reaction temperature, presence of inhibitors (including oxygen), and presence or absence of light will impact the successful polymerization.  AIBN has a 10 hr half-life of about 64 deg C.

In the early 1980s, I was supervisor of a research project which involved polymerizing MMA using AIBN as initiator. Of course, the amount of initiator had to be much smaller than the amount of monomer. How much smaller is dependent on the average molecular weight of the final product "PMMA" that is sought. More initiator will lead to lower average M.W of polymer since this is free radical polymerization.

My student & I used  a molar ratio of initiator to monomer "1/100"  and polymerization went fine after washing the inhibitor inside MMA & drying it. The initiator was fresh & recrystallized before use.

I think that 2% "as my friend Prof. Asit Samui suggested" will work as well. Getting PMMA is not a problem if polymerization is done using clean dry equipment as well as pure dry monomer under dry nitrogen blanket.

Thank you for all the answers and tips from your very knowledge and experience.  

Forgive me, but I have to ask again:  

I will be using MAA (monomer) is within the range of 1000 millimole/Liter to 10,000 mmol/L (using only 10 ml volume (0.01L) solution, the number of moles of MAA is within the range of 0.01   to 0.10  moles).  Base on the varying amounts of monomer, the mole fraction is within 0.15 to 0.16;  or  15 to16 mole %.

Is is correct to say that I should use about 0.20 grams AIBN (mw=164.21 g/mol)?  That is 0.02 x 0.16 x 164.21 grams/mol= 0.20 grams AIBN? constant for all the different sets of solutions in varyign amounts of monomer and crosslinker?

 Thank you for the support.

Please correct me if I am mistaken. MAA usually means methacrylic acid which polymerizes to give a water-soluble poly(methacrylic acid). I worked on this monomer& polymerized it free radically using AIBN as initiator at a molar ratio of 1/100 of initiator/monomer.

It is easy to polymerize by using a reflux system. You just put the monomer & initiator in r.b. flask to which an open condenser "with water in & out" is attached vertically. Two aluminum pans (one containing warm water & the other containing ice) ought to be present near the polymerization system. You first place the warm water pan to surround the r.b.flask (to dissociate the initiator) & then when you see little bubbles, you quickly surround the flask with the ice bath.

The polymerization is highly exothermic & it leads to a so-called "popcorn polymerization". If care is not applied, the polymer will expand passing through the condenser & hitting the ceiling of the fume cupboard. Just take care & everything will be fine. Best wishes.

Note: You may ask why 1/100 in my 2 answers.Well, that was a "tip" from the giant chemical industry "I.C.I".