thank you very much for your answer.

Maybe i will try your advise to change the solvent.

Dear Tati Nurhayati, the problem you have faced will encounter generally in many such bulk polymerization method.

Follow these steps in sequence:

Step 1. Dissolve the template in the porogenic solvent (Was Theophylline template completely soluble in chloroform..? (If not try with dimethyl sulfoxide or some other solvents, as polarity of solvents affect the complete dissolution of templates)

Step 2. Then add MAA Monomer and then EDMA in sequence to the template mixture prepared in step 1. (Try with EGDMA if possible).

Step 3. Fill these mixtures to glass ampoules or vial. Then sonicate for about 5 min and Nitrogen gas must be bubbled for 10 minutes (Sonication and N2 gas flushing inside the mixture removes oxygen and maintains inert condition which is essential for free radical formation)

Step 4.  Then add Benzoyl peroxide to the Glass ampoules and then it will be properly sealed under inert condition.

Step.5. The glass ampoule containing the polymerization mixture will be then placed in a circulating water bath maintained at 65°C for 24 h. (In our case we maintained this temperature, and for your template different temperature may apply)

Before starting the experiment calculate the molar ratio of all these (template, monomer, croslinker, initiator and solvents, and use only exact quantities, you may use excess of initiator, no problem.

  A control (reference) imprint i.e. non-imprinted polymer (NIP) will be prepared similar to imprinted polymer except the addition of template

One of our article is enclosed for your reference, Hope I have clarified your doubts… All the best.

Article Synthesis and application of cephalexin imprinted polymer fo...

Dear Laxmana Naik, thank you very much for your answer .

I would like to discuss a view things about the synthesis procedure.

1. The solubility of theophylline in chloroform is 9.1 mg/ml. But, in most of the literatures i have read , they dissolve theophylline in chloroform exceeding its solubility limit. 

For example, in a literature ( written by Vlatakis et al. http://www.nature.com/nature/journal/v361/n6413/abs/361645a0.html) 4.7 gram of theophylline is dissolved in 250 ml of chloroform.

In my case, i use 0.025 mg of theophylline in 2 ml of chloroform. After i dissolved theophylline in chloroform, it wasn't completely dissolved. But after i added MAA into the mixture, it was dissolved completely. In my opinion, It was because of theophylline is soluble in acid such as MAA.

Is it okay if i do this? Or should i use the amount of theophylline that is able to dissolve completely in chloroform (0.0182 mg in 2 ml of chloroform)?

2. In step 5, While the polymerization mixture is placed in a waterbath, should it be sealed? What is the purpose of it? Is it to prevent the mixture from air exposure? Or to prevent it from vaporizing? Since we used a volatile solvent.

3. Does the size of the glass ampoule or vial influence the polymerization process? 

In my case, the total volume of the polymerization mixture was about 2-3 ml. Should i use a 5ml, 10 ml, or 20 ml vial?

I dont have any glass ampoule, so i use a vial in step 5 of the synthesis procedure.

Thank you.

First thing is Please cross check the  Theophylline template: it is available in Two forms: hydrated and anhydrous theophylline. So Its solubility varies.

Yes...It must be sealed to prevent vaporization. So in your case at Polymerization temperature most of the chloroform would have got evaporated and it was not available for polymerization reaction.

No matter, u can use any suitable size vial...or Test tube, it must be made from soda glass, so  that it can be easily sealed with the help of burner.  or use any other suitable devise, search in internet... u will get more details.

Dear, Laxmana Naik. Thank you very much for your answer, i really appreciate it.

I have tried to synthesize the MIP according to your suggestions. 

I use anhydrous theophylline as the template and EGDMA as the cross-linker.

The molar ratio was approximately  1/4 for theophylline/MAA and 1/4 for MAA/EGDMA

First, i tried to use rubber cap wrapped by parafilm to seal the vial. After 24 hours in the oven at 60 C, unfortunately the parafilm melted, so the vial was slightly opened. The clear pre-polymerization mixture was turned white, and no liquid. But, the surface of the rigid polymer was kind of cracked.

Second, i used rubber cap wrapped by tape so that it can prevent the rubber cap from opening. With the similar condition, the clear pre-polymerization mixture was turned white, and no cracked on the surface, but i still found some liquid above the rigid polymer. 

What is the liquid could be? Is it the solvent? Or is it the remainder monomer that did not polymerize?

And, is it proper for the clear pre-polymerization mixture turned white after polymerization? 

 In some articles, for MIP prepared by theophylline as template, it said that the rigid polymer was white (some said colorless white). But, Most of the articles didn't describe the colour of the polymer.

Thank you.

Dear Tati Nurhayati...

Please continue the binding study of the prepared MIP., Nothing to worry.

I have attached a photograph of 1 Vials, You can get these type of tubes, search in website or ask the local glassware supplier, thy will help u. The thing is it must be air tight, please do not allow to evaporate the contents. In some MIP preparation this is also one of the critical parameter to be monitored.

After filling all  materials in this tube (templates, monomer, Cross-linker) sonicate it and then add initiator, and then heat seal it. Then keep it for polymerization.

Use of rubber cap is not recommended, it will add contaminants or impurity ...bcz the solvents, monomer and  cross-linker may dissolve rubber cap , its residues may interfere in the polymerization. 

Do not worry about the free moisture which is gets accumulates on the top layer of the polymer,  During radical mediated reaction some water gets released (as that of SDS-PAGE) or some of the reactant materials evaporates and then gets collects on the top layer after condensing.

Do not worry about colour of polymer, any way it needs to be purified with Soxhlet extraction and washings.

Dear Laxmana Naik,

Thank you very much for your explanation.

I have read your article and it is said that you broke the glass ampoule after the polymerization process. In my case, because some free moisture was found, i hesitated to break it. So i opened the seal and removed the moisture. Then, i found out that on top of the rigid polymer there was a gel-like layer.

In my opinion, maybe the gel-like layer was formed because it was in the interface of the rigid polymer and free moisture. I kept the sample overnight and the gel-like layer was gone (evaporated) and it turned into flakes on top of the rigid polymer. 

I removed the flakes and took the rigid polymer and ground it.

I am uncertain about what i did. Was it appropriate? Or, is there any better way to seperate the moisture and get the pure polymer?

Thank you very much.

Best regards,

Tati

Dear Tati.. Do not worry about that top layer. It has been clearly explained in my previous answer. this type of gel is usually seen in radical initiated polymerization reaction,  So discard this top layer.