Hello everyone,
I took 1% PLA and dissolved it in 200mL DCM to prepare a 200mL PLA solution. I took 100mL PLA solution and dissolved 1% antimicrobial material into it. I allowed the solution to stir for several hours to ensure complete miscibility. After this, I poured the solution onto a glass petri dish, covered it immediately with aluminium foil and allowed it to dry overnight for 2 days under the fume hood. Then I stored the sample in a desiccator for some time before analysis. I took out the sample from the desiccator and as soon as I tried to separate it from the glass petri dish, some of the film tore, some got stuck strongly to the glass petri dish and some came out separately. What might be the reason for this and how can I get rid of this issue? Please help urgently. Thanks
Cracking and tearing of PLA films can be addressed by controlling solvent evaporation, incorporating plasticizers, and using non-stick substrates or release agents. Adjusting drying conditions and modifying the polymer blend can also improve film flexibility and reduce adhesion to the casting surface.
The previous answer consider all possible origins of the cracking. I have not much to add on the methodoilgies proposed ; eventually a less crystallizable and less viscous PLA could help
Wipe the glass petri dish with a little of a non-sticking agent such as silicone oil that allowing to release the film easily without sticking
Yes, try to add little amount of glycerol while synthesis. It will provide flexibility and stop cracking of the sample.
PLA is a material with high Tg, slow crystallization rate and low HDT temperature. therefore, you can eliminate this problem by using a compatibilizer with a different flexible polymer that will accelerate this crystallization. the use of low molecular weight ethylene glycol in the use of plasticizer given in previous recommendations will also support the solution.
All the possible suggestions have been recorded. Are you going to make thin film. Then use spin coating method. As suggested by Pattara, change solvent and increase concentration. The rate of evaporation will control the film quality. Of course you may use a release agent. Regarding plasticizer, it depends whether that goes with your formulation. You may heat the film a little bit before stripping it out.
Asit Baran Samui, Thank you so much for your comment and your suggestion. I am avoiding heating the film because DCM, used as a solvent here, is highly volatile and dries quickly at room temperature under the fume hood. Also, by increasing the concentration, won't the thickness of my thin film increase? I am trying to synthesise thin films of 100 - 200 nm thickness. I am working with the spin coating method as well. I will use the suggestion given by Jamal Babawati here to see whether I can separate my thin films or not after solvent casting without heating.
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