Peng-Fei Gou

Drug-grafted seven-arm amphiphilic star poly(ε-caprolactone-co-carbonate)-b-poly(ethylene glycol)s based on a cyclodextrin core: synthesis and self-assembly behavior in water

Novel well-defined drug-grafted seven-arm amphiphilic star poly(e-caprolactone-co-carbonate)-b-poly(ethylene glycol)s based on a β-CD core [CDS-P(CL-co-DTC)-D-b-PEG] have been synthesized by the combination of controlled ring-opening polymerization (CROP), esterification coupling reactions and “click” reactions. First, 5,5-dibromomethyl-trimethylene carbonate (DBTC) bearing two bromide pendent groups was synthesized and used to copolymerize with CL to prepare seven-arm star random copolymers [CDS-P(CL-co-DBTC)] in the presence of per-2,3-acetyl-β-cyclodextrin and Sn(Oct)2. Second, esterification coupling reaction between CDS-P(CL-co-DBTC) and carboxyl-terminated mPEG led to amphiphilic seven-arm star copolymers [CDS-P(CL-co-DBTC)-b-PEG]. Subsequently, the bromide pendent groups on CDS-P(CL-co-DBTC)-b-PEG had been converted into azide groups by treating with NaN3. Finally, alkyne functionalized ibuprofen had been grafted onto the hydrophobic block of the star copolymers by copper(I)-catalyzed “click” reaction. 1H NMR, FT-IR and SEC analyses confirmed the well-defined drug grafted star architecture. These copolymers could self-assemble into multi-morphological aggregates in water, which were characterized by dynamic light scattering (DLS) and transmission electron microscopy (TEM).

Amphiphilic seven-arm star triblock copolymers with diverse morphologies in aqueous solution induced by crystallization and pH

Well-defined amphiphilic seven-arm star triblock copolymers containing hydrophobic crystalline poly(ε-caprolactone)(PCL) blocks, hydrophobic non-crystalline poly(tert-butyl acrylate)(PtBA) blocks and hydro-philic poly(ethylene glycol)(PEG) blocks were precisely synthesized by a combination of ring-opening polymeriza-tion(ROP), atom transfer radical polymerization(ATRP) and “click” reaction. Such star copolymers could self-assemble into “core-shell-corona” micelles and “multi-layer” vesicles depending on the fraction of each block. Meanwhile, the selective hydrolysis of middle PtBA blocks into the poly(acrylic acid)(PAA) blocks allowed the star block copolymers to further change their morphologies of aqueous aggregates in response to pH values.