writer：Weizhong Yuan, Jinying Yuan*, Mi Zhou, Caiyuan Pan
keywords：atom transfer radical polymerization (ATRP); dendrimers; fluorescence;
source：期刊
specific source：J. Polym. Sci. Part A: Polym. Chem., 2008,46,2788-2798
Issue time：2008年

Novel and well-defined pyrene-containing eight-arm star-shaped dendrimer-
like copolymers were successfully achieved by combination of esterification,
atom transfer radical polymerization (ATRP), divergent reaction, ring-opening polymerization(ROP), and coupling reaction on the basis of pentaerythritol. The reaction of pentaerythritol with 2-bromopropionyl bromide permitted ATRP of styrene (St) to form four-arm star-shaped polymer (PSt-Br)4. The molecular weights of these polymers could be adjusted by the variation of monomer conversion. Eight-hydroxyl starshaped polymer (PSt-(OH)₂)₄ was produced by the divergent reaction of (PSt-Br)₄ with diethanolamine. (PSt-(OH)₂)₄ was used as the initiator for ROP of e-caprolactone(CL) to produce eight-arm star-shaped dendrimer-like copolymer (PSt-b-(PCL)₂)₄. The molecular weights of (PSt-b-(PCL)₂)₄ increased linearly with the increase of monomer. After the coupling reaction of hydroxyl-terminated (PSt-b-(PCL)2)4 with 1-pyrenebutyric acid, pyrene-containing eight-arm star-shaped dendrimer-like copolymer (PSt-b-(PCL-pyrene)₂)₄ was obtained. The eight-arm star-shaped dendrimer-like copolymers presented unique thermal properties and crystalline morphologies, which were different from those of linear poly(e-caprolactone) (PCL). Fluorescence analysis indicated that (PSt-b-(PCL-pyrene)₂)₄ presented slightly stronger fluorescence intensity than 1-pyrenebutyric acid when the pyrene concentration of them was the same. The obtained pyrene-containing eight-arm star-shaped dendrimer-like copolymer has potential applications in biological fluorescent probe, photodynamic therapy, and optoelectronic devices.