Effect factors of micelle preparation for a pH-sensitive copolymer containing zwitterionic sulfobetaines

•We discussed the influence of preparation factors using solvent evaporation method.•The micelle prepared using a pH-sensitive copolymer containing zwitterionic sulfobetaines.•The preparation factors may influence the micellization process.•The sizes and zeta-potential of the micelles controlled by preparation parameters.•The size further influences the drug loading/drug release of micelles. Polymeric micelles have wide applications for the delivery of water-insoluble drugs. Solvent evaporation method is commonly used to prepare polymer micelles, although the influential factors of micellization process of this method are insufficiently clear. In the work, a pH-sensitive copolymer containing sulfobetaines, poly(ɛ-caprolactone)-b-poly(N,N-diethylaminoethylmethacrylate)-r-poly(N-(3-sulfopropyl)-N-methacryloxyethy-N,N-diethylammoniumbetaine) (PCLDEAS), was selected as the material for micelle preparation by solvent evaporation method to investigate the influence of preparation factors on the micelle sizes/size distributions and zeta-potentials. The preparation variables included copolymer concentration, the organic solvent/water phase ratio, the micelle concentration and the compositions of aqueous phase. The influence of these factors further on drug loading/releasing was also studied. In conclusion, to control the preparation factors of solvent evaporation method may be employed to control the properties of the micelles including sizes, drug loading and drug release.