Synthesis of liquid crystalline poly(1‐pentyne)s and fabrication of polyacetylene–perovskite hybrids

Poly(1‐pentyne)s containing biphenyl and phthalimido pendant groups with different spacer lengths {P 1 (m); ? [HC?C(CH₂)₃O? Biph? OCO(CH₂)_mN(CO)₂C₆H₄]_n? , Biph?4,4′? biphenylyl; m = 7, 10} are synthesized in satisfactory yields by WCl₆‐Ph₄Sn catalyst in toluene at elevated temperatures. The structures and properties of the polymers are characterized and evaluated by IR, NMR, TGA, DSC, POM, and XRD analyses. Both of the polymers are thermally stable (T_d ≥ 300 °C) and exhibit nematicity at high temperatures. Their phthalimido groups are converted into amino groups by hydrolysis, which can, after acidification, complex with lead(II) bromide to furnish polyacetylene–perovskite hybrids in high yields. The organic components contribute good solubility to the hybrids, while the perovskite framework induces the polyacetylene chains to align within the inorganic sheets. The hybrids emit a strong UV light of 374 nm upon photoexcitation, whose quantum yield increases with an increase in the spacer length. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 3538–3550, 2006     

Stilbene‐containing polyactylenes: Molecular design,synthesis, and relationship between molecular structure and NLO properties

Polyacetylenes ( P1–P4 ) containing different stilbene groups, ? [(CH?C) ? Ph? CH?CH? Ph? R]_n? (R?OC_mH_2m+1 (m = 4 ( P1 ), 10 ( P2 ), 16 ( P3 )), or NO₂ ( P4 )) were designed and synthesized, respectively, using [Rh(nbd)Cl]₂ as a catalyst. Their structures and properties were characterized and evaluated by FTIR, ¹H‐NMR, ¹³C‐NMR, GPC, and UV, PL, respectively. The optical limiting and nonlinear optical properties were investigated by using a frequency doubled, Q‐switched, mode‐locked Continuum ns/ps Nd:YAG laser system and their optical limiting mechanism was discussed. It is surprising to see that the stilbene pendants endow the polyacetylenes with a high thermal stability (T_d ≥ 270 °C), novel optical limiting properties and large third‐order nonlinear optical susceptibilities (up to 4.61 × 10^?10 esu). The optical limiting mechanism is mainly originated from reverse saturable absorption of molecules. In addition, it is found that the polymer with electron accepted NO₂ moiety exhibits better optical properties than that with electron donated alkoxy group because of larger π electron delocalization and dipolar effect. The strong interaction between stilbene pendants and the polyene main chain significantly results in red‐shift of fluorescence emitting peak. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 4529–4541, 2008     

Synthesis and properties of azobenzene‐containing poly(1‐alkyne)s with different functional pendant groups

1‐Alkynes containing azobenzene mesogenic moieties [HC?C(CH₂)₉? O? ph? N?N? ph? O? R; R = ethyl ( 1 ), octyl ( 2 ), decyl ( 3 ), (S)‐2‐methylbutyl ( 4 ), or (S)‐1‐ethoxy‐1‐oxopropan‐2‐yl ( 5 ); ph = 1,4‐phenyl] were synthesized and polymerized in the presence of a Rh catalyst {(nbd)Rh⁺[B(C₆H5)₄]^?; nbd = 2,5‐norbornadiene} to yield a series of liquid‐crystalline polymers in high yields (e.g., >75%). These polymers had moderate molecular weights (number‐average molecular weight ≥ 12,000), high cis contents in the main chain (up to 83%), good thermal stability, and good solubility in common organic solvents, such as tetrahydrofuran, chloroform, and dichloromethane. These polymers were thoroughly characterized by a combination of infrared, nuclear magnetic resonance, thermogravimetric analysis, differential scanning calorimetry, polarized optical microscopy, and two‐dimensional wide‐angle X‐ray diffraction techniques. The liquid‐crystalline behavior of these polymers was dependent on the tail group attached to the azobenzene structure. Poly‐ 1 , which had the shortest tail group, that is, an ethyl group, showed a smectic A mesophase, whereas poly‐ 2 , poly‐ 3 , and poly‐ 5 , which had longer or chiral tail groups, formed smectic C mesophases, and poly‐ 4 , which had another chiral group attached to the azobenzene structure, showed a chiral smectic C mesophase in both the heating and cooling processes. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 4532–4545, 2006     

Nitro‐substituted iron(II) tridentate bis(imino)pyridine complexes as high‐temperature catalysts for the production of α‐olefins

A new series of nitro‐substituted bis(imino)pyridine ligands {2,6‐bis[1‐(2‐methyl‐4‐nitrophenylimino)ethyl]pyridine, 2,6‐bis[1‐(4‐nitrophenylimino)ethyl]pyridine, (1‐{6‐[1‐(4‐nitro‐phenylimino)‐ethyl]‐pyridin‐2‐yl}‐ethylidene)‐(2,4,6‐trimethyl‐phenyl)‐amine, and 2,6‐bis[1‐(2‐methyl‐3‐nitrophenylimino)ethyl]pyridine} and their corresponding Fe(II) complexes [{p‐NO₂? o‐Me? Ph? N?C(Me)? Py? C(Me)?N? Ph? o‐ Me? p‐NO₂}FeCl₂ ( 10 ), L₂FeCl₂ ( 11 ), {m‐NO₂? o‐Me? Ph? N?C(Me)? Py? C(Me)?N? Ph? o‐Me? m‐NO₂}FeCl₂ ( 12 ), and {p‐NO₂? Ph? N?C(Me)? Py? C(Me)?N? Mes}FeCl₂ ( 14 )] were synthesized. According to X‐ray analysis, there were shortenings of the axial Fe? N bond lengths (up to 0.014 Å) in para‐nitro‐substituted complex 10 and (up to 0.015 Å) in meta‐nitro‐substituted complex 12 versus the Fe(II) complex without nitro groups [{o‐Me? Ph? N?C(Me)? Py? C(Me)?N? Ph? o‐Me}FeCl₂ ( 1 )]. Complexes 10 , 12 , and 14 afforded very active catalysts for the production of α‐olefins and were more temperature‐stable and had longer lifetimes than parent non‐nitro‐substituted Fe(II) complex 1 . The reaction between FeCl₂ and a sterically less hindered ligand [p‐NO₂? Ph? N?C(Me)? Py? C(Me)?N? Ph? p‐NO₂] resulted in the formation of octahedral complex 11 . A para‐dialkylamino‐substituted bis(imino)pyridine ligand [p‐NEt₂? o‐Me? Ph? N?C(Me)? Py? C(Me)?N? Ph? o‐Me? p‐NEt₂] and the corresponding Fe(II) complex [{p‐NEt₂? o‐Me? Ph? N?C(Me)? Py? C(Me)?N? Ph? o‐Me? p‐NEt₂}FeCl₂ ( 16 )] were synthesized to evaluate the effect of enhanced electron donation of the ligand on the catalytic performance. According to X‐ray analysis, there was a shortening (up to 0.043 Å) of the axial Fe? N bond lengths in para‐diethylamino‐substituted complex 16 in comparison with parent Fe(II) complex 1 . © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 2615–2635, 2006     

Preparation and property of two soluble oxadiazole‐containing functional polyacetylenes

Two novel high‐molecular weight functional polyacetylenes (PA) bearing oxadiazole group as a pendant, poly(2‐(4‐octoxyphenyl)‐5‐(4‐ethynylphenyl)‐1,3,4‐oxadiazole) ( P1 ) and poly(2‐(4′‐octoxyphenyl)‐5‐(4′‐propynyloxyphenyl)‐1,3,4‐oxadiazole) ( P2 ) were synthesized by [Rh(nbd)Cl]₂‐Et₃N catalysts. Both polymers were soluble in common organic solvents such as CHCl₃ and tetrahydrofuran. Their structures and properties were characterized and evaluated with FTIR, NMR, UV, thermogravimetric analysis, GPC, optical‐limiting and nonlinear optical analyses, respectively. The results show that linkage of oxadiazole chromophore to PA main chain has improved the nonlinear optical (NLO) property of PA, and endowed PA with novel optical limiting properties and enhanced thermal stability. Simultaneously, the optical‐limiting and NLO properties of the polymers were sensitive to their molecular structures. P1 with oxadiazole directly incorporated into PA main chain as a pendant showed better performances and larger third‐order nonlinear optical susceptibility than P2 with oxadiazole incorporated into PA main chain via a spacer. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 2072–2083, 2008     

Synthesis and helicity of optically active poly(N‐propargylphosphonamidates) having chiral phosphorus center

Novel chiral N‐propargylphosphonamidate monomers (HC?CCH₂NHP(?O)R? O? menthyl, 1 : R = CH₃, 2 : R = C₂H₅, 3 : R = n‐C₃H₇, 4 : R = Ph) were synthesized by the reaction of the corresponding phosphonic dichlorides with menthol and propargylamine. Pairs of diastereomeric monomers 1 – 4 with different ratios were obtained due to the chiral P‐center and menthyl group. One diastereomer could be separated from another one in the cases of monomers 1 and 2 . Polymerization of 1 – 4 with (nbd)Rh⁺[η⁶‐C₆H₅B^?(C₆H₅)₃] as a catalyst in CHCl₃ gave the polymers with number‐average molecular weights ranging from 5000 to 12,000 in 65–85%. Poly( 1 )–poly( 4 ) exhibited quantitative cis contents, and much larger specific rotations than 1 – 4 did in CHCl₃. The polymers showed an intense Cotton effect around 325 nm based on the conjugated polyacetylene backbone. It was indicated that the polymers took a helical structure with predominantly one‐handed screw sense, and intramolecular hydrogen bonding between P?O and N? H of the polymers contributed to the stability of the helical structure. Poly( 1a ) and poly( 2a ) decreased the CD intensity upon raising CH₃OH content in CHCl₃/CH₃OH. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 1515–1524, 2007     

Synthesis of poly(1‐chloro‐2‐arylacetylene)s with high cis‐content and examination of their absorption/emission properties

A series of 1‐chloro‐2‐arylacetylenes [Cl‐C?C‐Ar, Ar = C₆H₅ ( 1 ), C₆H₄‐p‐i Pr ( 2 ), C₆H₄‐p‐Oi Pr ( 3 ), C₆H₄‐p‐NHC(O)Ot Bu ( 4 ), and C₆H₄‐o‐i Pr ( 5 )] were polymerized using (tBu₃P)PdMeCl/silver trifluoromethanesulfonate (AgOTf) and MoCl₅/SnBu₄ catalysts. The corresponding polymers [poly( 1 )–poly( 5 )] with weight‐average molecular weights of 6,500–690,000 were obtained in 10–91% yields. THF‐insoluble parts, presumably high‐molecular weight polymers, were formed together with THF‐soluble polymers by the Pd‐catalyzed polymerization. The Pd catalyst polymerized nonpolar monomers 1 and 2 to give the polymers in yields lower than the Mo catalyst, while the Pd catalyst polymerized polar monomers 3 and 4 to give the corresponding polymers in higher yields. The ¹H NMR and UV–vis absorption spectra of the polymers indicated that the cis‐contents of the Pd‐based polymers were higher than those of the Mo‐based polymers, and the conjugation length of the Pd‐based polymers was shorter than that of the Mo‐based polymers. Pd‐based poly( 5 ) emitted fluorescence most strongly among poly( 1 )–poly( 5 ). © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55 , 382–388     

Synthesis and chiroptical properties of L‐valine‐containing poly(phenylacetylene)s with (a)chiral pendant terminal groups

Poly(phenylacetylene)s containing L ‐valine residues (P 1 ) with (a)chiral pendant terminal groups R^(*) [?(HC?C{C₆H₄CONHCH[CH(CH₃)₂]COO? R^(*)})_n?]; R^(*) = 1‐octyl (P 1 o), (1S,2R,5S)‐(+)‐menthyl [P 1 (+)], (1R,2S,5R)‐(?)‐menthyl [P 1 (?)] are designed and synthesized. The polymers are prepared by organorhodium catalysts in high yields (yield up to 88%) with high molecular weights (M_w up to ?6.4 × 10⁵). Their structures and properties are characterized by NMR, IR, TGA, UV, and circular dichroism analyses. All the polymers are thermally fairly stable (T_d ≥ 320 °C). The chiral moieties induce the poly(phenylacetylene) chains to helically rotate in a preferred direction. The chirality of the pendant terminal groups affects little the helicity of the polymers but their bulkiness stabilizes the helical conformation against solvent perturbation. The backbone conjugation and chain helicity of the polymers can be modulated continuously and reversibly by acid. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 2117–2129, 2006     

Nanostructured polymetallaynes of controlled length: Synthesis and characterization of oligomers and polymers from 1,1′‐bis‐(ethynyl)4,4′‐biphenyl bridging Pt(II) or Pd(II) centers

The reactivity of square planar palladium(II) and platinum(II) complexes in trans or cis configuration, namely trans or cis‐[dichlorobis(tributylphosphine)platinum(II)] and trans‐[dichlorobis(tributylphosphine)palladium(II)] with 1,1′‐bis(ethynyl) 4,4′‐biphenyl, DEBP, leading to π‐conjugated organometallic oligomeric and polymeric metallaynes, was investigated by a systematic variation of the reaction conditions. The formation of polymers and oligomers with defined chain length [? M(PBu₃)₂ (C?C? C₆H₄? C₆H₄? C?C? )]_n (n = 3–10 for the oligomers, n = 20–50 for the polymers) depends on the configuration of the precursor Pt(II) and Pd(II) complexes, the presence/absence of the catalyst CuI, and the reaction time. A series of model reactions monitored by XPS, GPC, and NMR ³¹P spectroscopy showed the route to modulate the chain growth. As expected, the nature of the transition metal (Pt or Pd) and the molecular weight of the polymers markedly influence the photophysical characteristics of the polymetallaynes, such as optical absorption and emission behavior. Polymetallaynes with nanostructured morphology could be obtained by a simple casting procedure of polymer solutions. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 3311–3329, 2007     

Synthesis,Interionic Structure,and Reactivity toward CO and p‐Methylstyrene of Palladacyclic Compounds Bearing α‐Diimine Ligands

Palladacyclic compounds [Pd(C₆H₄(C₆H₅C?O)C?N? R)(N? N)] [X] (R = Et, ⁱPr, 2,6‐ⁱPr₂C₆H₃; N? N = bpy = 2,2′‐bipyridine, or 1,4‐(o,o′‐dialkylaryl)‐1,4‐diazabuta‐1,3‐dienes; [X]^? = [BF₄]^? or [PF₆]^?) were synthesized from the dimers [{Pd(C₆H₄(C₆H₅C?O)C?N? R)(μ‐Cl)}₂] and N? N ligands. Their interionic structure in CD₂Cl₂ was determined by means of ¹⁹F,¹H‐HOESY experiments and compared with that in the solid state derived from X‐ray single‐crystal studies. [Pd(C₆H₄(C₆H₅C?O)C?N? R)(N? N)] [X] complexes were found to copolymerize CO and p‐methylstyrene affording syndiotactic or isotactic copolymers when bpy or 1,4‐(o,o′‐dimethylaryl)‐1,4‐diazabuta‐1,3‐dienes were used, respectively. The reactions with CO and p‐methylstyrene of the bpy derivatives were investigated. Two intermediates derived from a single and a double insertion of CO into the Pd? C bonds were isolated and completely characterized in solution.     

Nonlinear optical side‐chain polymers post‐functionalized with high‐β chromophores exhibiting large electro‐optic property

Electro‐optic side‐chain polymers have been synthesized by the post‐functionalization of methacrylate isocyanate polymers with novel phenyl vinylene thiophene vinylene bridge (FTC) nonlinear optical chromophores. For this application, FTC‐based chromophores were modified in their electronic donor structure, exhibiting much larger molecular hyperpolarizabilities compared with the benchmark FTC. Of these new chromophores, absorption spectra, hyper‐Rayleigh scattering experiment, and thermal analysis were carried out to confirm availability as effective nonlinear optical units for electro‐optic side‐chain polymers. The electro‐optic coefficients (r₃₃) of obtained polymers were investigated in the process of in situ poling by monitoring the temperature, current flow, poling field, and electro‐optic signal. Compared with the nonsubstituted analogue, benxyloxy modified FTC chromophore significantly achieved higher nonlinear optical property, exhibiting molecular hyperpolarizability at 1.9 μm of 4600 × 10^?30 esu and an r₃₃ value of 150 pm/V at the wavelength of 1.31 μm. Synthesized electro‐optic polymers showed high glass transition temperature (T_g), so that the temporal stability examination exhibited >78% of the electro‐optic intensity remaining at 85 °C over 500 h. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010     

Benzodifuran‐containing well‐defined π‐conjugated polymers for photovoltaic cells

Two well‐defined alternating π‐conjugated polymers containing a soluble electroactive benzo[1,2‐b:4,5‐b′]difuran (BDF) chromophore, poly(BDF‐(9‐phenylcarbazole)) (PBDFC), and poly(BDF‐benzothiadiazole) (PBDFBTD) were synthesized via Sonogashira copolymerizations. Their optical, electrochemical, and field‐effect charge transport properties were characterized and compared with those of the corresponding homopolymer PBDF and random copolymers of the same overall composition. All these polymers cover broad optical absorption ranges from 250 to 750 nm with narrow optical band gaps of 1.78–2.35 eV. Both PBDF and PBDFBTD show ambipolar redox properties with HOMO levels of ?5.38 and ?5.09 eV, respectively. The field‐effect mobility of holes varies from 2.9 × 10^?8 cm² V^?1 s^?1 in PBDF to 1.0 × 10^?5 cm² V^?1 s^?1 in PBDFBTD. Bulk heterojunction solar cell devices were fabricated using the polymers as the electron donor and [6,6]‐phenyl‐C₆₁‐butyric acid methyl ester as the electron acceptor, leading to power conversion efficiencies of 0.24–0.57% under air mass 1.5 illumination (100 mW cm^?2). These results indicate that their band gaps, molecular electronic energy levels, charge mobilities, and molecular weights are readily tuned by copolymerizing the BDF core with different π‐conjugated units. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Photocurrent Enhancement in Diketopyrrolopyrrole Solar Cells by Manipulating Dipolar Anchoring Terminals on Alkyl‐Chain Spacers

We chose DPP‐BDT‐DPP {DPP=diketopyrrolopyrrole, BDT=4,8‐di‐[2‐(2‐ethylhexyl)‐thienyl]benzo[1,2‐b:4,5‐b′]dithiophene} as a model backbone and varied the anchoring groups [? C₅H₁₁, ? COOCH₃, and ? SiCH₃(OSiCH₃)₂] terminated on the N‐substituted alkyl‐chain spacer of the DPP units to study the effect of anchoring terminals on the morphology of blend film and on the device performances of bulk heterojunction solar cells. By replacing the nonpolar ? C₅H₁₁ anchoring terminal with the polar ? COOCH₃ anchoring terminal leads to an enhancement in the short‐circuit current density (J_sc) (4.62 vs. 9.32 mA cm^?2), whereas the value of J_sc sharply decreases to 0.45 mA cm^?2 if the ? C₅H₁₁ anchoring terminal is replaced by a ? SiCH₃(OSiCH₃)₂ group. The changes in J_sc are associated with changes in the π–π stacking distance (3.39→3.34 Å vs. 3.39→3.45 Å) and the phase size (50→20 nm vs. 50→>250 nm) through alteration of the anchoring group from ? C₅H₁₁ to ? COOCH₃ versus from ? C₅H₁₁ to ? SiCH₃(OSiCH₃)₂. Interestingly, the anchoring terminals bring about drastic changes in molecular orientations, which result in different out‐of‐plane hole transport. This is the first time this effect has been systemically demonstrated to improve photocurrent generation by manipulating the dipolar anchoring groups terminated on the alkyl‐chain spacer.     

Mechanism and characterization of alkylene‐ and p‐ethylenebenzylene‐spaced polycarbosilanes ceramic precursor synthesized by electropolymerization

An electropolymerization of haloalkylhalosilanes (Cl? R? SiCH₃Cl₂) that possess two types of electroactive sites, that is, the C? Cl and Si? Cl bond is described. The one‐pot synthesis method is shown to yield branched polycarbosilanes having a regular carbon block‐spaced silicon backbone structure. A series of branched polycarbosilanes, [? R? SiCH₃? ]_n with R being ? CH₂? , ? C₂H₄? , ? C₃H₆? , and ? CH₂? C₆H₄? C₂H₄? , have been successfully electropolymerized with M_n up to 42,600 Dalton. Experimental and simulation cyclic voltammetry of these monomers and the computational examination of their LUMOs are applied to study the electropolymerization mechanism. The results suggest that polymerization proceeds by iterating steps involving (1) electroreduction of a C? Cl bond to a carbanion, which is catalyzed by silylanion radical [Cl SiCl(CH₃)RCl] and/or Ni(0)/TDA‐1; and (2) nucleophilic attack of carbanions to Si? Cl bonds of a second monomer or oligomer to extend the polymer chain. The investigation reveals that the R spacer has a considerable impact on the polymerizability of the corresponding monomer. Such interfacial polymerization resembles a template polymerization, leading to unique microstructures that were preserved even after converted to silicon carbide ceramics at high temperatures. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 7677–7689, 2008     

Soluble polynorbornenes with pendant carbazole derivatives as host materials for highly efficient blue phosphorescent organic light‐emitting diodes

We report novel host polymers for a high‐efficiency polymer‐based solution‐processed phosphorescent organic light‐emitting diode with typical blue‐emitting dopant bis(4,6‐difluorophenylpyridinato‐N,C²)iridium(III) picolinate (FIrpic). The host polymers, soluble polynorbornenes with pendant carbazole derivatives, N‐phenyl‐9H‐carbazole ( P1 ), N‐biphenyl‐9H‐carbazole ( P2 ), and 9,9′‐(1,3‐phenylene)bis‐9H‐carbazole (mCP) ( P3 ) are efficiently synthesized by vinyl addition polymerization of norbornene monomers using Pd(II) catalyst in combination with 1‐octene chain transfer agent. The polymers exhibit high thermal stability with high decomposition (T_d5 > 410 °C) and glass transition temperatures (T_g ≈ 268 °C). The HOMO (ca. ?5.5 to ?5.7 eV) and LUMO (ca. ?2.0 to ?2.1 eV) levels with the high triplet energy of about 2.7–3.0 eV suggest that the polymers are suitable for a host material for blue emitters. Among the solution‐processed devices that were fabricated based on the emissive layers containing the P1 ? P3 host doped with various concentrations of FIrpic (7–13 wt %), the best device with P3 host exhibits power efficiency of 3.0 lm W^?1 and external quantum efficiency of 4.0% at a luminance of 1000 cd m^?2 that is outstanding among the polymeric rivals. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Topological polymer chemistry by electrostatic self‐assembly

Recent developments in topological polymer chemistry are outlined. First, nonlinear polymer topologies are systematically classified on the basis of topological considerations of constitutional isomerism in a series of alkanes (C_nH_2n+2), monocycloalkanes (C_nH_2n), and polycycloalkanes (C_nH_2n?2, C_nH_2n?4, etc.). Various pairs of topological isomers are identified in randomly coiled, flexible polymer molecules with cyclic and branched structures. An electro‐ static self‐assembly and covalent fixation strategy has subsequently been developed for the efficient synthesis of a variety of topologically unique polymers, including monocyclic and polycyclic polymers, topological isomers, and topological block copolymers. In this process, new telechelics with moderately strained cyclic onium salt groups carrying multifunctional carboxylate counteranions have been designed as key polymeric precursors. Further extensions of topological polymer chem‐ istry have been achieved by the use of cyclic telechelics (kyklo‐telechelics) and cyclic macromonomers, obtainable also by means of the electrostatic self‐assembly and covalent fixation process. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 2905–2917, 2003     

Judiciously balancing steric and electronic influences on 2,3‐diiminobutane‐based Pd(II) complexes in nourishing polyethylene properties

A new series of palladium complexes ( Pd1–Pd5 ) ligated by symmetrical 2,3‐diiminobutane derivatives, 2,3‐bis[2,6‐bis{bis(4‐FC₆H₄)₂CH}₂‐4‐(alkyl)C₆H₂N]C₄H₆ (alkyl = Me L1 , Et L2 , ⁱ Pr L3 , ^t Bu L4 ) and 2,3‐bis[2,6‐bis{bis(C₆H₅)₂CH}₂‐4‐{(CH₃)₃C}C₆H₂N]C₄H₆ L5 , have been prepared and well characterized, and their catalytic scope toward ethylene polymerization have been investigated. Upon activation with MAO, all palladium complexes ( Pd1–Pd5) exhibited good activities (up to 1.44 × 10⁶ g (PE) mol^?1(Pd) h^?1) and produced higher molecular weight polyethylene in the range of 10⁵ g mol^?1 with precise molecular weight distribution (M _w/M _n = 1.37–1.77). One of the long‐standing limiting features of the Brookhart type α‐diimine Pd(II) catalysts is that they produce highly branched (ca. 100/1000 C atoms) and totally amorphous polymer. Conversely, herein Pd5 produced polymers having dramatically lower branching number (28/1000) as well as improved melting temperature up to 73.1 °C showing well‐controlled linear architecture, and very similar to polyethylene materials generated by early‐transition‐metal based catalysts. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55 , 3214–3222     

Polymerization of substituted phenylacetylenes with a novel,water‐soluble Rh–vinyl complex in water

A novel, water‐soluble Rh complex, (nbd)Rh[PPh₂(m‐NaOSO₂C₆H₄)] [C(Ph)?CPh₂] ( 1 ) was synthesized by the reaction of [(nbd)RhCl]₂, Ph₂P(m‐NaOSO₂C₆H₄) and Ph₂C?C(Ph)Li, whose structure was determined by NMR and IR spectroscopies. The Rh catalyst 1 induced the polymerization of phenylacetylene (PA) in water to give two kinds of polymers; one was soluble in organic solvents such as tetrahydrofuran (THF) and CHCl₃, and the other was insoluble in common organic solvents. The polymerization of sodium p‐ethynylbenzoate (p‐NaOCO‐PA) homogeneously proceeded with 1 in water at 60 °C to give the polymer in high yield. Poly(p‐NaOCO‐PA) was treated with 1 N HCl and then reacted with (CH₃)₃SiCHN₂ to obtain poly(p‐MeOCO‐PA). The methyl‐esterified polymer was insoluble in THF and CHCl₃, which suggests that the formed poly(p‐MeOCO‐PA) has cis–cisoidal structure. The polymer obtained from the polymerization of [p‐CH₃(OCH₂CH₂)₂O₂CC₆H₄]C?CH with 1 in water was soluble in methanol, ethanol, and THF, and partly soluble in water. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2100–2105, 2004     

Cyclic and linear poly(ferrocenylene alkylene)s synthesized from addition‐condensation polymerization of ferrocene with aldehydes

Oligo‐ and poly(ferrocenylene alkylene)s, [Fe(C₅H_5‐x)(C₅H_5‐y)CHR]_n (x = y = 1 or x = 2, y = 0; R = alkyl, aryl), were synthesized by Lewis acid‐promoted addition‐condensation polymerization of ferrocene with aldehydes. The reaction of alkyl aldehydes, such as n‐hept‐CHO, EtCHO and nBuCHO, with ferrocene yields a mixture of the cyclic and linear poly(ferrocenylene alkylene)s, while aryl aldehyde, such as C₆F₅CHO, CF₃C₆H₄‐4‐CHO and MeC₆H₄‐4‐CHO, forms the linear polymers exclusively. The linear polymer has terminal ? Fe(C₅H₄)(C₅H₅) and ? CH₂Aryl groups, which are characterized by high resolution mass spectroscopy. Results of addition‐condensation polymerization of ferrocenemethanol catalyzed by BF₃ indicate that the propagating polymer of the above addition‐condensation polymerization contains terminal 1‐hydroxyalkyl‐ferrocenylene group, ? Fe(C₅H₄)[C₅H₄{CH(OH)R}]. The trimer prepared from ferrocene and paraformaldehyde dimethylacetal contains 1,1′‐, 1,2‐, and 1,3‐ferrocenylene units, suggesting that the polymers obtained from alkyl and aryl aldehydes are also composed of these structural units. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 3627–3635     

Synthesis and properties of polyacetylenes with directly attached bis(4‐alkoxyphenyl)terephthalate mesogens as pendants

Liquid‐crystalline, monosubstituted polyacetylenes containing lateral pendants of bis(4‐alkoxyphenyl)terephthalate with no flexible spacers and alkoxy tails {RO, where R is CH₃ [P(1)] or C₆H₁₃ [P(6)]} were synthesized, and the effects of the backbone structure and alkoxy tails on the properties of the polymers were investigated. The polymerizations of acetylene monomers were carried out with chloronorbornadiene rhodium(I) dimer as a 1,2‐insertion catalyst in toluene. The structures and properties of the monosubstituted polyacetylenes were characterized and evaluated with nuclear magnetic resonance, infrared spectroscopy, thermogravimetry, differential scanning calorimetry, polarized optical microscopy, ultraviolet spectroscopy, and photoluminescence analyses. The molecular weights of the polymers were measured by gel permeation chromatography. The polymer with long tails (p‐hexyloxy), that is, P(6), formed a smectic mesophase upon heating above the melting temperature, but the other one with short tails (p‐methoxy), that is, P(1), could not exhibit liquid crystallinity at elevated temperatures. The steric effect of bulky, liquid‐crystalline mesogens and a direct connection with the main chain prevented the planar conformation of the polyene backbone and, therefore, led to the lower absorption and emission wavelength of the polymers. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 2499–2509, 2006