The permeability of lipid bilayer membranes to glucose and carboxyfluorescein has been studied in model membranes. Using an enzyme assay, the permeability of glucose was monitored spectrometrically with both large and giant unilamellar vesicles (LUVs and GUVs). The permeability of carboxyfluorescein was studied by entrapping the dye and monitoring its leakage over time from a single GUV. Permeability study using GUVs may provide new information that cannot be obtained from LUVs.The stability of lipid membranes was enhanced by incorporating polymer scaffold. LUVs were prepared with hydrophobic monomers partitioned and then polymerized inside the hydrophobic interior of the lipid bilayers. The sizes of the formed polymers were characterized using gel permeation chromatography and mass spectrometry. This study suggests that large molecular weight polymers were formed inside the lipid bilayers and that the stability of the membranes is related to the size of the polymers.