Electromechanical Limits of Polymersomes

Abstract

Self-assembled membranes of amphiphilic diblock copolymers enable comparisons of cohesiveness with lipid membranes over the range of hydrophobic thicknesses $d\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}3--15\mathrm{nm}$. At zero mechanical tension the breakdown potential ${V}_{c}$ for polymersomes with $d\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}15\phantom{\rule{0ex}{0ex}}\mathrm{nm}$ is $9\mathrm{V}$, compared to $1\mathrm{V}$ for liposomes with $d\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}3\phantom{\rule{0ex}{0ex}}\mathrm{nm}$. Nonetheless, electromechanical stresses at breakdown universally exhibit a ${V}_{c}^{2}$ dependence, and membrane capacitance shows the expected strong $d$ dependence, conforming to simple thermodynamic models. The viscous nature of the diblock membranes is apparent in the protracted postporation dynamics.