UNASSIGNED: We present an in situ cryo-electron microscopy (cryoEM) study of mixed @entity3880 ( @entity3880 )/ @entity852 (PS) brush-grafted 67 nm @entity3440 nanoparticles in organic and aqueous solvents. These organic-inorganic nanoparticles are predicted to be environmentally responsive and adopt distinct brush layer morphologies in different solvent environments. Although the self-assembled morphology of mixed @entity3880 /PS brush-grafted particles has been studied previously in a dried state, no direct visualization of microphase separation was achieved in the solvent environment. CryoEM allows the sample to be imaged in situ, that is, in a frozen solvated state, at the resolution of a transmission electron microscope. Cryo-electron tomograms (cryoET) were generated for mixed @entity3880 /PS brush-grafted nanoparticles in both @entity6442 ( @entity9104 , a nonselective good solvent) and water (a selective solvent for @entity3880 ). Different nanostructures for the mixed brushes were observed in these two solvents. Overall, the brush layer is more compact in water, with a thickness of 18 nm, as compared with an extended layer of 27 nm in @entity9104 . In @entity9104 , mixed @entity3880 /PS brushes are observed to form laterally separated microdomains with a ripple wavelength of 13.8 nm. Because of its lower grafting density than that of @entity3880 , PS domains form more or less cylindrical or truncated cone-shaped domains in the @entity3880 matrix. In water, @entity3880 chains are found to form a more complete shell around the nanoparticle to maximize their interaction with water, whereas PS chains collapse into the core of surface-tethered micelles near the @entity3440 core. The cryoET results presented here confirm the predicted environmentally responsive nature of @entity3880 /PS mixed brush-grafted nanoparticles. This experimental approach may be useful for the design of future mixed brush-grafted nanoparticles for nano- and biotechnology applications.

In Situ Characterization of Binary Mixed Polymer Brush-Grafted XXXX Nanoparticles in Aqueous and Organic Solvents by Cryo-Electron Tomography.

@entity852 :: ('MESH:D011137', 'Chemical') :: ['polystyrene'] @entity9104 :: ('CHEBI:17741', 'Chemical') :: ['DMF'] @entity3880 :: ('CHEBI:51133', 'Chemical') :: ['PAA', 'poly(acrylic acid)'] @entity6442 :: ('MESH:D004126', 'Chemical') :: ['N,N-dimethylformamide'] @entity3440 :: ('MESH:D012822', 'Chemical') :: ['silica']
@entity3440 :: (MESH:D012822,Chemical) :: ['Silica']
