Addition of PGS normally enhance the hydrophilicity of the scaffolds. The PGS could have dissolved in the solution owing to the –OH groups in PGS.

I agree with Amin Shavandi. Please perform microscopical anaylsis of mat before and after swelling test.

Thank you for your answers. Microscopic analysis would be helpful. However, PGS/PCL scaffolds don't degrade within this time according to the literature. I think I figured out the problem and I will do another trials.