Cargo Release from Polymeric Vesicles under Shear

In this paper we study the release of cargo from polymeric nano-carriers under shear. Vesicles formed by two star block polymers— [Formula: see text] ([Formula: see text]) and [Formula: see text] ([Formula: see text])—and one linear block copolymer— [Formula: see text] ([Formula: see text]), are investigated using dissipative particle dynamics (DPD) simulations. [Formula: see text]- and [Formula: see text]-blocks are solvophobic and [Formula: see text]-block is solvophilic. The three polymers form vesicles of different structures. The vesicles are subjected to shear both in bulk and between solvophobic walls. In bulk shear, the mechanisms of cargo release are similar for all vesicles, with cargo travelling through vesicle membrane with no preferential release location. When sheared between walls, high cargo release rate is only observed with [Formula: see text] vesicle after it touches the wall. For [Formula: see text] vesicle, the critical condition for high cargo release rate is the formation of wall-polymersome interface after which the effect of shear rate in promoting cargo release is secondary. High release rate is achieved by the formation of solvophilic pathway allowing cargo to travel from the vesicle cavity to the vesicle exterior. The results in this paper show that well controlled target cargo release using polymersomes can be achieved with polymers of suitable design and can potentially be very useful for engineering applications. As an example, polymersomes can be used as carriers for surface active friction reducing additives which are only released at rubbing surfaces where the additives are needed most.