A series of nanoparticles with phase-separated structures by 1,1-diphenylethene controlled one-step soap-free emulsion copolymerization and their application in drug release

A facile one-step approach to synthesize various phase-separated porous,raspberry-like, flower-like, core-shell and anomalous nanoparticles andnanocapsules via 1,1-diphenylethene （DPE） controlled soap-free emulsioncopolymerization of styrene （S） with glycidyl methacrylate （GMA）, or acrylicacid （AA） is reported. By regulating the mass ratio of S/GMA, transparentpolymer solution, porous and anomalous P（S-GMA） particles could be produced.The P（S-GMA） particles turn from flower-like to raspberry-like and then toanomalous structures with smooth surface as the increase of divinylbenzene（DVB） crosslinker. Transparent polymer solution, nanocapsules and core-shellP（S-AA） particles could be obtained by altering the mole ratio of S/AA; anomalousand raspberry-like P（S-AA） particles are produced by adding DVB. Theunpolymerized S resulted from the low monomer conversion in the presence ofDPE aggregates to form nano-sized droplets, and migrates towards the externalsurfaces of the GMA-enriched P（S-GMA） particles and the internal bulk of theAA-enriched P（S-AA） particles. The nano-sized droplets function as in situporogen, porous P（S-GMA） particles and P（S-AA） nanocapsules are producedwhen the porogen is removed. This novel facile, one-step method with excellentcontrollability and reproducibility will inspire new strategies for creatinghierarchical phase-separated polymeric particles with various structures by simplyaltering the species and ratio of comonomers. The drug loading and releaseexperiments on the porous particles and nanocapsules demonstrate that therelease of doxorubicin hydrochloride is very slow in weakly basic environmentand quick in weakly acidic environment, which enables the porous particlesand nanocapsules with promising potential in drug delivery applications.