I dissolved PEO 10K - PLLA 14K in toluene at the concentration of 50 mg/ml, 25 mg/ml, and 5 mg/ml including 30 min of sonication.
When I sonicated them at room temperature, only 5 mg/ml was clear solution but others were cloudy.
However, when I did at 50 Celcius degree, all the solutions were clear initially, but only 50 mg/ml solution became cloudy as it naturally cooled to room temperature.
I measured and compared water/solution interfacial tensions, and I found that solutions sonicated at room temperature showed relatively higher surface tension than those sonicated at 50 Celcius degree. I think this is because some of polymers are not dissolved or highly aggregated so that they did not effectively act as surfactants.
My questions are
1. What does clear/unclear solution mean? Is it not dissolved? Or is it highly aggregated?
2. Solutions of 25 mg/ml and 5 mg/ml were clear in both cases but have different interfacial tension. How can I explain this?
Hosu
At 50 deg. C you dissolve more. After cooling some part gets out of the solution and you see it as a cloud.
Same with ultrasoniocation (it also heats up the solution).
At the end you ahould know that ultrasonic radition can brake or degrade your compound (check my papers on cavitation).
Regards
GB
You investigated the toluene - polymer phase separation. When there was a low concentration of polymer in the water, there was no phase separation. When there was a mud solution, it means that you went behind the binodal. When heated, i.e. at elevated temperatures, phase separation changes. Binodal and spinodal change their position. You need to read the theory of phase separation of polymers in solution. You can see the phase separation close to your systems, the surfactant-water system in
Article Liquid Polyamorphous Transition and Self-Organization in Aqu...
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