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    Öğe
    Synthesis and characterization of an A2B2-type miktoarm star copolymer based on poly(?-caprolactone) and poly(cyclohexene oxide)
    (Springer, 2019) Uyar, Zafer; Genli, Nasrettin; Cay, Bahri; Arslan, Ulku; Durgun, Mustafa; Degirmenci, Mustafa
    An A(2)B(2)-type miktoarm star copolymer with two linear poly(epsilon-caprolactone) (PCL) and two linear poly(cyclohexene oxide) (PCHO) arms was synthesized by using ring-opening polymerization (ROP), click chemistry, and photoinduced cationic polymerization, respectively. The ROP of epsilon-CL with a dihydroxy functional initiator, 3-cyclohexene-1,1-dimethanol, produced a well-defined two-arm PCL with a cyclohexene end-functional group, (PCL)(2)-CH. The subsequent bromination of (PCL)(2)-CH followed by azidation gave a diazido end-functionalized PCL, (PCL)(2)-(N-3)(2). Then, a well-defined two-arm PCL macrophotoinitiator with benzoin end-functional groups, (PCL)(2)-(PI)(2), was prepared by the azide/alkyne click reaction of this (PCL)(2)-(N-3)(2) and PI-alkyne, a separately prepared benzoin photoinitiator bearing a terminal alkyne group. Solid data obtained from the H-1 NMR, FT-IR, GPC, UV, and fluorescence spectroscopic studies proved the successful formation of the macrophotoinitiator having a core connected to two PCL chains and two benzoin photofunctional groups (PI). Finally, a novel A(2)B(2)-type miktoarm star copolymer was synthesized via photoinduced free radical-promoted cationic polymerization of cyclohexene oxide (CHO) monomer using (PCL)(2)-(PI)(2) as photoinitiator. The obtained star copolymer consists of two PCL arms as A blocks and two PCHO arms as B blocks, (PCL)(2)-(PCHO)(2), and was characterized by H-1 NMR, FT-IR, and GPC measurements. The thermal behaviors of all the intermediate and final polymers were studied by thermogravimetric and differential thermal analysis (TG/DTA).
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    Öğe
    Synthesis of well-defined bisbenzoin end-functionalized poly(?-caprolactone) macrophotoinitiator by combination of ROP and click chemistry and its use in the synthesis of star copolymers by photoinduced free radical promoted cationic polymerization
    (Taylor & Francis Ltd, 2017) Uyar, Zafer; Degirmenci, Mustafa; Genli, Nasrettin; Yilmaz, Ayse
    A new well-defined bisbenzoin group end-functionalized poly(epsilon-caprolactone) macrophotoinitiator (PCL-(PI) 2) was synthesized by combination of ring opening polymerization (ROP) and click chemistry. The ROP of epsilon-CL monomer in bulk at 110 degrees C, by means of a hydroxyl functional initiator namely, 3-cyclohexene-1-methanol in conjunction with stannous-2-ethylhexanoate, (Sn(Oct)(2)), yielded a well-defined PCL with a cyclohexene end-chain group (PCL-CH). The bromination and subsequent azidation of the cyclohexene end-chain group gave bisazido functionalized poly(epsilon-caprolactone) (PCL-(N-3)(2)). Separately, an acetylene functionalized benzoin photoinitiator (PI-alkyne) was synthesized by using benzoin and propargyl bromide. Then the click reaction between PCL-(N-3)(2) and PI-alkyne was performed by Cu(I) catalysis. The spectroscopic studies revealed that poly(epsilon-caprolactone) with bisbenzoin photoactive functional group at the chain end (PCL-(PI)(2)) with controlled chain length and low-polydispersity was obtained. This PCL-(PI)(2) macrophotoinitiator was used as a precursor in photoinduced free radical promoted cationic polymerization to synthesize an AB(2)-type miktoarm star copolymer consisting of poly(epsilon-caprolactone) (PCL, as A block) and poly(cyclohexene oxide) (PCHO, as B block), namely PCL(PCHO)(2).