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Title: Synthesis of hyperbranched polyarylenes and poly(aroylarylene)s by polycyclotrimerization of alkynes and their applications as photoresist and precursors for magnetic ceramics
Authors: Dong, Hongchen
Issue Date: 2005
Abstract: A new series of hyperbranched (co)polymers are prepared by (co)polycyclotrimerization of diynes HC≡CPh-Si(R1R2)-PhC≡CH (R1, R2 ≡ H or CH3), and bis(aroylacetylene)s HC≡CCO-C6H4-R-C6H4-OCC≡CH [R = alkyl or oligo(ethylene oxide) groups] and HC≡CCOArOCC≡CH (Ar contains fluorene, carbazole, triphenylamine, or ferrocene unit) with ferrocene-containing monoyne. The monomers are synthesized in high yields by multi-step reactions. Polymerizations of the monomers gave high molecular weight polymers in high yields (Mw up to 4.6 x 104 Da and isolation yield up to 99%). The structures and properties of the polymers are well characterized by common spectroscopic methods, such as IR, NMR, UV, PL, TGA, DSC, XRD, XPS, SEM and TEM. Polycyclotrimerizations of silicon-containing diynes are efficiently catalyzed by a transition-metal catalyst, TaBr5, giving poly(silylenearylene)s with 1,2,4-trisubstitued benzene rings as the predominated isomeric structure. The intracyclotrimerization reactions during the polymerization result in the formation of intramolecular rings in the resultant polymers. Hyperbranched poly(aroylarylene)s with degree of branching up to unity are prepared by a new synthetic route-piperidine-catalyzed polycyclotrimerization of bis(aroylacetylene)s. Due to its ionic mechanism, the polycyclization is strictly regioselective and highly functionality-tolerant. All the polymers are thermally stable, losing merely 5% of their weights at high temperatures (up to 580 °C) and carbonizing in high yields (up to 81%) at 900 °C. Upon photoexcitation, the polymers emit UV and green lights with quantum yields ranged from 0.5% to 30.0%. Hyperbranched poly(aroylarylene)s are readily photocrosslinked upon UV irradiation with high photosensitivities (D0.5 down to 43 mJ/cm2) and generate well-resolved photopatterns with nanometer resolution. Ceramizations of ferrocene-containing polymers at 1000 °C under nitrogen yield soft ferromagnetic ceramics with high magnetizabilities (Ms up to 22 emu/g) but low hysteresis losses (down to 0.07 kOe). Pyrolysis of the patterned polymer films with micro resolution produces magnetic ceramic patterns with excellent shape retention in the lateral direction.
Description: Thesis (M.Phil.)--Hong Kong University of Science and Technology, 2005
xx, 191 leaves : ill. ; 30 cm
HKUST Call Number: Thesis CHEM 2005 Dong
Appears in Collections:CHEM Master Theses

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