Polymersomes, which are stable and robust vesicles made of block copolymer amphiphiles, are good candidates for drug carriers or micro/nanoreactors. Polymer chemistry enables almost unlimited molecular design of responsive polymersomes whose degradation upon environmental changes has been used for the slow release of active species. Here, we propose a strategy to remotely trigger instantaneous polymersome bursting. We have designed asymmetric polymer vesicles, in which only one leaflet is composed of responsive polymers. In particular, this approach has been successfully achieved by using a UV-sensitive liquid-crystalline copolymer. We study experimentally and theoretically this bursting mechanism and show that it results from a spontaneous curvature of the membrane induced by the remote stimulus. The versatility of this mechanism should broaden the range of applications of polymersomes in fields such as drug delivery, cosmetics and material chemistry.asymmetric polymer vesicles ͉ liquid-crystalline copolymer ͉ spontaneous curvature ͉ UV-sensitive

International audiencePolymersomes are vesicles made of amphiphilic diblock copolymers. Giant polymersomes of several tens of microns in diameter can be prepared from low T(g) (glass transition temperature) flexible (coil-coil) copolymers by processes such as rehydration swelling or electroformation. These techniques are, however, inefficient in producing giant polymersomes composed of high T(g) and/or rigid-flexible (rod-coil) copolymers. We have used an alternative method based on the formation of an inverted emulsion to produce giant unilamellar rod-coil polymersomes. We have selected copolymers whose hydrophobic moieties are glassy liquid crystalline polymers. The viscoelasticity of individual polymersomes has been measured by micropipette aspiration. Whereas the elastic modulus was found to be of the same order of magnitude as the one of prototypical vesicles made of coil-coil copolymers, the membrane viscosity of this new class of polymersomes was about three orders of magnitude more viscous than their coil-coil counterparts. The versatile method used here to form giant polymersomes could be useful for designing and studying novel functional polymer capsules. The results highlight the possibility of widely tuning the mechanical properties of polymersomes by selecting or synthesizing the proper copolymer