(377g) Study of Isothermal Solubilities of Benzene, DCE, DCM, and Chloroform in Diblock and Triblock Copolymers of Polycaprolactone and Polyethylene Glycol at 298.15K Using a QCM

Studying sorption and diffusion of solvents into polymer systems has always been difficult due to low diffusion rates resulting in slow equilibration. Since the Quartz crystal microbalance is mass sensitive in its operation, the polymer film coated on its surface can be made very thin, and the time needed for the solvent to reach equilibrium is thereby greatly reduced from that of other methods.

Triblock and diblock copolymers of Polycaprolactone (PCL) and Polyethylene glycol (PEG) find applications in various biomedical fields. Both homopolymers PCL and PEG have been approved by FDA for biomedical applications and the thermosensitive copolymers of PCL/PEG are largely used as injectable hydrogels in tissue engineering and tissue regeneration due to their slower degradation rate and higher gel strength.

Using a quartz crystal microbalance (QCM) the sorption of several different solvents: benzene, dichloroethane (DCE), chloroform, and dichloromethane (DCM), in triblock and diblock copolymers of PCL and PEG were observed at 298.15 K. The solvent-polymer interactions are quantified using the Flory-Huggins model. Weight based activity coefficients at infinite dilution were obtained from the model and trends with the PCL/PEG ratio in the copolymers are shown.