Giant unilamellar vesicles (GUVs) are self-assembled biomimetic model membrane systems useful for examining biomembrane properties and building artificial cell membranes for membrane protein incorporation and encapsulation of other biomolecules. Hydrogel-assisted rehydration is an emerging technique to form GUVs under physiological conditions at high yields circumventing the shortcomings of traditional techniques such as electroformation and gentle hydration. Here, we present a new hydrogel material, porous negatively charged poly (methacrylic acid-co-ethylene glycol diacrylate) (xPMAA) for the hydrogel-assisted rehydration method. Porous xPMAA membranes are fabricated using an unconventional solvent-free initiated chemical vapor deposition technique and utilized as hydrogel substrates for vesicle formation. Zwitterionic and charged lipid mixtures are deposited on hydrogel membranes as thin lipid films and subsequently swollen in an aqueous hydration buffer. Vesicle yield and size are controlled by surface roughness, density and charge of the polymer. Our findings show that high hydrogel porosity and reduced electrostatic interactions between the polymer and the lipid are preferred for vesicle formation. In addition, the presence of ions in the hydration buffer affects the yield of GUV formation due to Debye screening of the polymer charge by buffer ions.