Browsing by Author "Wu, Jingbo"
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Item Synthesis and Characterization of a Novel Fluorinated Bismaleimide via a Nucleophilic Addition-Elimination Reaction and its Polymeric Networks(Royal Society of Chemistry, 1905-07-07) Wu, Jingbo; Xi, Yang; McCandless, Gregory T.; Kulikov, Oleg V.; Menon, Remya; Novak, Bruce M.; Wu, Jingbo; Xi, Yang; McCandless, Gregory T.; Kulikov, Oleg V.; Menon, Remya; Novak, Bruce M.The commercially available octafluorocyclopentene (OFCP) as both a fluorinated building block and a linker has been successfully utilized to prepare a new fluorinated bismaleimide monomer OFCP-BMIvia a nucleophilic addition-elimination reaction. The resulting OFCP-BMI is characterized by 1H, 13C, 19F nuclear magnetic resonance (NMR) spectroscopy, attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), and high resolution mass spectrometry. The monomer OFCP-BMI reacts with a free radical initiator or self-cures to prepare its resins. No obvious glass transition temperature (Tg) below 260°C was observed for the self-curing resin suggesting that a highly cross-linked polymeric network was formed. The self-curing resin exhibits excellent thermal stability with the on-set weight loss temperature (Ton-setd) of 445°C and a 50% char yield at 800°C under a nitrogen atmosphere. The resin obtained by a free radical polymerization process exhibits less thermal stability and a lower char yield than the self-curing resin due to its lower cross-linking density. The self-curing resin exhibits a low dielectric constant (Dk = 2.5).Item Towards an Understanding of Structure-Nonlinearity Relationships in Triarylamine-based Push-Pull Electro-Optic Chromophores: The Influence of Substituent and Molecular Conformation on Molecular Hyperpolarizabilities(Royal Soc Chemistry, 2014-02-17) Wu, Jingbo; Wilson, Blake A.; Smith, Dennis W., Jr.; Nielsen, Steven O.; 2012052347 (Smith, DW); Smith, Dennis W., Jr.; Nielsen, Steven O.We calculated the second-order hyperpolarizability (beta) of a series of triarylamine (TAA) based donor-bridge-acceptor (D-π-A) push-pull type nonlinear optical (NLO) chromophores with different electron donor moieties and the same thiophene π-bridge and dicyanovinyl electron acceptor using a time-dependent Hartree-Fock (TDHF) approach within the software package MOPAC 2012. NLO chromophores with various quantities and positions of methoxy groups in the TAA donor moiety were investigated. The relationship between NLO properties and the electronic or geometric structures of the TAA donor subunit is discussed through the calculation results. Both substituent and conformational effects affect the delocalization of the nitrogen lone pair into the aryl rings, leading to a dramatic influence on the nonlinear optical properties. Introduction of methoxy groups at the ortho positions of the TAA moiety has a larger influence on the molecular hyperpolarizability and dipole moment than the introduction of methoxy group at the para or meta positions. Our calculation results demonstrate how to improve the NLO properties of TAA based chromophores while meeting practical device requirements.Item Utilization of a Meldrum's Acid Towards Functionalized Fluoropolymers Possessing Dual Reactivity for Thermal Crosslinking and Post-Polymerization Modification(2015-04-30) Wu, Jingbo; Iacono, Scott T.; McCandless, Gregory T.; Smith, Dennis W., Jr.; Novak, Bruce M.; 253728855 (Smith, DW); 116300023 (Novak, BM); Wu, Jingbo; Iacono, Scott T.; McCandless, Gregory T.; Smith, Dennis W., Jr.; Novak, Bruce M.New thermally cross-linkable and/or post-functionalizable perfluorocyclobutyl (PFCB) polymers containing Meldrum's acid moieties have been successfully prepared via the thermal cyclopolymerization of a new Meldrum's acid functionalized aromatic trifluorovinyl ether (TFVE) monomer.