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Nearly monodispersed silica core−poly(N-vinylcarbazole) shell (SiO2@PVK) microspheres of 226, 235, and 244 nm in average diameters were first synthesized by surface-initiated distillation-precipitation polymerization of N-vinylcarbazole, in the presence of divinylbenzene, from the 197 nm silica template microspheres prepared by the sol−gel reaction of tetraethyl orthosilicate (TEOS) and 3-(trimethoxysilyl)propyl methacrylate (MPS). The SiO2@PVK−PNIPAM core−shell hairy microspheres (PNIPAM = poly(N-isopropylacrylamide)) were subsequently prepared by grafting the PNIPAM chains (Mn = 11 600 g/mol, polydispersity index =1.32), prepared a priori by reversible addition−fragmentation chain transfer (RAFT) polymerization, to the SiO2@PVK microspheres via the thiol−ene click chemistry. The grafting density of PNIPAM brushes on the SiO2@PVK microspheres was about 0.1 chains/nm2. Hairy hollow microspheres with a fluorescent and cross-linked PVK shell and temperature-responsive PNIPAM brushes were finally obtained, a...

A new type of double hydrophilic block copolymer, poly(ethylene oxide) (PEO)-block-poly(glycerol monoacrylate) (PGA) have been synthesized via atom transfer radical polymerization of solketal acrylate (SA) using PEO-Br as macro-initiator, and subsequent hydrolysis of the acetal-protecting group in 1N HCl solution in THF. The polymerization is of a "living" nature and the copolymers with controlled molecular weight and narrow polydispersity (M(w)/M(n) = 1.01-1.03) were obtained. The complete hydrolysis of the acetal-protecting group was verified by IR and NMR spectroscopies. A hydrophobic fluorescent compound, 1-pyrenecarboxaldehyde, was used as a model drug, which was covalently bound to the PEO-b-PGA block copolymer via a pH-sensitive acetal linkage. The kinetics of the pyrene release was studied in THF/aqueous buffers at pH 5.0 (close to pH in endosomes) and 7.4 (pH of blood plasma) by fluorescent spectroscopy. The pyrene was released much faster at pH 5.0 than that at pH 7.4. The micelle behavior in solutions at pH 5.0 and 7.4 was studied by dynamic light scattering. All results show that this double hydrophilic PEO-b-PGA is a promising candidate for potential application as drug carrier for those carbonyl-containing hydrophobic drugs.

Hexa-armed star block copolymers, s-[poly(l-lactide)-b-poly(styrene-co-N-acryloxysuccinimide)]6 (s-[PLLA-b-poly(St-co-NAS)]6) with triphenylene core have been successively prepared by the combination of ring-opening polymerization and atom transfer radical copolymerization, and they were used in the self-assembly in tetrahydrofuran, and the micelles with triphenylene core and PLLA as inner layer as well as poly(St-co-NAS) as shell were formed. After shell was cross-linked, PLLA was hydrolyzed in aqueous NaOH solution, the hollow spheres were formed. The structures, molecular weight and polydispersity index of the polymers were characterized by their 1H NMR and FT-IR spectra, as well as GPC. Their morphologies were studied by TEM. The influence factors on the formation of various morphologies are under investigation.