Studies on poly(iminomethylenes)

A variety of simple alkyl and aryl isocyanides have been polymerized using 0.5% NiCl₂ in ethanol as a catalyst. The resulting poly(iminomethylenes) have been characterized by carbon-13 NMR spectroscopy and their polystyrene-equivalent molecular weights have been determined by gel permeation chromatography. Straight chain aliphatic isocyanides having from three to ten carbon atoms in the chain form readily solyble polymers having molecular weights (M_w) in the general range 10,000 to 30,000. Neopentyl isocyanide unlike tert-butyl isocyanide forms an insoluble polymer. A number of new soluble aryl isocyanide polymers have been obtained. However, aryl isocyanides having a single alkyl substituent (CH₃, C₂H₅, CF₃) in the ortho position give only insoluble polymers, whereas aryl isocyanides having alkyl substituents in both ortho positions (e.g., 2,6-(CH₃)₂C₆H₃NC and 2,4,6-(CH₃)₃C₆H₂NC) fail to polymerize under these conditions. The highest molecular weight soluble aryl isocyanide homopolymer is obtained from 3-CH₃OC₆H₄NC(M_w = 26,000). The trimethylsilyl substituted isocyanide (CH₃)₃SiCH₂CH₂NC has been obtained from LiCH₂NC and (CH₃)SiCH₂Cl and gives a brown soluble homopolymer with a molecular weight (M_w) of 19,000.     

Isothermal crystallization kinetics of poly(ethylene terephthalate)s of different molecular weights

The isothermal crystallization kinetics and morphology of poly(ethylene terephthalate) (PET) polymers of different molecular weights have been studied by means of differential scanning calorimetry and transmission microscopy (TM). The kinetic parameters of Avrami exponent n, the rate constant k, half time t _1/2, rate at 50 % crystallinity, τ _1/2 for crystallization of different PETs were evaluated from double logarithmic plots of log {?ln[1 ? X(t)]} versus log t, where X(t) is extent of crystallinity at a given crystallization temperature. The crystallization rate of polymers with high molecular weight found to be lower than that of polymers with low molecular weight, at the same crystallization temperature. It was found that the nucleation mechanism and growth dimension of polymers with low molecular weight are different from those of polymers with high molecular weight. The results of TM and isothermal crystallization kinetics showed a consistent trend for the crystallization of all PET polymers studied, comprising a primary stage and a secondary stage. The activation energy in the PET polymers of low molecular weight was found to be lower than that of polymers with high molecular weight.     

Synthesis and characterization of poly(phenylacetylenes) featuring activated ester side groups

Four monomers based on 4‐ethynylbenzoic acid have been synthesized, one of those featuring an activated ester. With the metathesis catalytic system WCl₆/Ph₄Sn, these acetylenic monomers could successfully be polymerized yielding conjugated polymers with molecular weights of around 10,000 to 15,000 g/mol and molecular weight distributions M_w/M_n ≤ 2.1. Also the copolymerization of phenylacetylene or methyl 4‐ethynylbenzoate with pentafluorophenyl 4‐ethynylbenzoate as reactive unit was conducted. Polymer analogous reactions of the reactive polymers and copolymers with amines have been investigated and it was found that poly(pentafluorophenyl 4‐ethynylbenzoate) featured a significant reactivity, such that reactions proceeded quantitatively even with aromatic amines. Moreover the UV‐Vis spectra of the activated ester based polymer before and after conversion with aliphatic amines showed a change, indicating an effect on the conjugated backbone of the polymers. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010     

Tetrahydrofuran and 3,3-bis(chloromethyl) oxetane triblock copolymers synthesized by two-end living cationic polymerization

Triblock copolymers based on tetrahydrofuran (THF) and 3,3-bis(chloromethyl) oxetane (BCMO), BCMO-block-THF-block-BCMO and poly(BCMO-co-THF)-THF-(BCMO-co-THF), have been synthesized by two-end living cationic polymerization with a bifunctional initiator, trifluoromethanesulfonic anhydride [(CF₃SO₂)₂O]. The polymers are obtained by using the two end propagating species of poly(THF) to initiate the sequential BCMO polymerization. The resulting polymers are characterized by infrared (IR), nuclear magnetic resonance (NMR), and differential scanning calorimetry (DSC), confirming that the polymers are ABA-type block copolymers. The identities of the molecular weights predetermined and which determined by GPC show the success of predetermining molecular weights of the polymers and preparing well-defined polymers. The narrow polydispersities, 1.1–1.3, indicate that the chains are propagating by a living mechanism. © 1993 John Wiley & Sons, Inc.     

聚芳亚胺的合成、结构与性能

以不同的二碘化合物和芳香二胺为单体,通过两种不同的方法经缩聚反应得到了系列高分子量、低分布的聚芳亚胺。其结构由FT-IR, 1H NMR1和元素分析表征。由DSC和TG测定结果可知,该系聚合物具有较高的玻璃化转变温度(Tg＞150℃)和良好的热稳定性(TD＞400℃)。另外,该系聚合物还表现出良好的溶解性能。     

Molecular modeling simulation and experimental measurements to characterize chitosan and poly(vinyl pyrrolidone) blend interactions

Blends of chitosan and poly(vinyl pyrrolidone) (PVP) have a high potential for use in various biomedical applications and in advanced drug‐delivery systems. Recently, the physical and chemical properties of these blends have been extensively characterized. However, the molecular interaction between these two polymers is not fully understood. In this study, the intermolecular interaction between chitosan and PVP was experimentally investigated using ¹³C cross‐polarization magic angle‐spinning nuclear magnetic resonance (¹³C CP/MAS NMR) and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). According to these experimental results, the interaction between the polymers takes place through the carbonyl group of PVP and either the OH? C₆, OH? C₃, or NH? C₂ of chitosan. In an attempt to identify the interacting groups of these polymers, molecular modeling simulation was performed. Molecular simulation was able to clarify that the hydrogen atom of OH? C₆ of chitosan was the most favorable site to form hydrogen bonding with the oxygen atom of C?O of PVP, followed by that of OH? C₃, whereas that of NH? C₂ was the weakest proton donor group. The nitrogen atom of PVP was not involved in the intermolecular interaction between these polymers. Furthermore, the interactions between these polymers are higher when PVP concentrations are lower, and interactions decrease with increasing amounts of PVP. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 1258–1264, 2008     

Preparation of new dioxygen-active triphenylantimony(V) catecholate-containing porous polymer

Novel porous polymers with 4-ethoxy-3,6-di-tert-butyl-o-benzoquinone grafted to the porous surface have been prepared via the secondary functionalization of porous polymer monoliths obtained by the photopolymerization of oligo(carbonate dimethacrylate) and hydroxyethyl methacrylate in methanol solution. These quinone-functionalized polymers have been applied for the synthesis of triphenylantimony(V) catecholate-containing polymers by the oxidative addition reaction of quinone moieties with SbPh₃. The obtained antimony-containing porous polymeric material is able to reversibly bind molecular oxygen in nearly quantitative yield. The rate of molecular oxygen sorption is 900 times higher for the porous material than that for the same film material and comparable with the process rate in solution. Copyright © 2016 John Wiley & Sons, Ltd.     

Synthesis of poly(ferrocenyldialkoxysilane) polymers and formation of gels by non-hydrolytic gelation methods

The synthesis of new 1,1′-ferrocenediyldialkoxysilanes Fe(η-C₅H₄)₂Si(OR)₂ M1-M3, with R = tBu, CH₂Ph, iPr, is described. The X-ray diffraction of a single crystal has been performed in the case of M1. Thermal ring opening polymerisation of M1-M3 yielded the corresponding poly(ferrocenylsilane) polymers P1-P3. These linear polymers are soluble in polar solvents and exhibit high molecular weights. M3 and P1 have been introduced in a silica matrix by non-hydrolytic condensation. The electrochemical properties of the obtained gels GM3 and GP1 have been studied.     

New tetradentate Schiff-base polymers: preparation of poly[2,5-(didodecyloxy)phenylene-1,4-diyl-alt-N,N-(o-phenylene)-bis(salicylideneiminato-4,4-diyl)] and poly[2,5-(didodecyloxy)phenylene-1,4-diyl-alt-N,N-(alkylidene)-bis(salicylideneiminato-4,4-diyl)]s

New tetradentate Schiff-base polymers, in which phenylene units alternate with salicylideneiminato units, have been prepared by condensation of 2,5-(didodecyloxy)-1,4-bis(3-formyl-4-hydroxyphenyl)benzene (DFHB) with appropriate diamines in a mixed solution of CHCl₃/toluene/acetic acid with 31-79% yields. DFHB as the key building block was prepared by the Suzuki reaction of 2,5-(didodecyloxy)benzene-1,4-diboronic acid with 5-bromosalicylaldehyde in a two-phase solution of tetrahydrofuran/water in the presence of NaHCO₃/Pd(PPh₃)₄ in 45% yield. The molecular structures of the prepared compounds were identified by spectroscopy. Their absorption spectroscopic profiles have been analyzed.     

Star-shaped polymers with a doubled fullerene (C60) branching center

Star-shaped regular homopolystyrenes with 22 arms and heteroarm polymers with 12 PS arms and 10 poly(2-vinypyridine) arms have been synthesized by consecutive coupling-functionalization-coupling reactions. The synthesis includes the following stages: the exhaustive grafting of fullerene C₆₀ by polystyryllithium chains (living hexaadducts); the coupling of hexaadducts with the use of dimethyldichlorosilane or 1,4-dibromobutane into twelve-arm macromolecules, where the branching center is composed of two covalently bonded fullerene C₆₀ molecules; functionalization of twelve-arm double-core PS stars during the action of excess dihalides (the replacement of lithium atoms with groups containing chlorine or bromine atoms); and the coupling of living chains of PS or poly(2-vinylpyridine) via reactions with halogen-containing groups at the branching center of double-core PS stars. Linear living polymers used as arms have been prepared by anionic polymerization. Exclusion chromatography has been used to control the individual stages of synthesis. The molecular characteristics of the PS precursor and of star-shaped polymers have been studied in terms of hydrodynamics and light scattering.     

Sustainable poly(ether amide)s from lignin-derived precursors

In recent years, there have been concerted efforts to replace petrochemical products with those from renewable sources due to the unsustainability of petroleum feedstock, and the continued volatility in the price. This work describes the synthesis and thermal properties of two new lignin-derived poly(ether-amide)s as alternative thermoplastics to petroleum-based commodities. Poly-4-(2-aminoethoxy)benzoate (PEAB) and poly-4-(2-aminoethoxy)-3-methoxybenzoate (PEAV) are synthesized by a melt polycondensation and characterized by ¹H NMR spectroscopy and thermal analysis. The number average molecular weight (M_n) of the polymers are estimated from the ¹H NMR spectroscopy analysis, and were shown to be 4100 and 12,000 g/mol for PEAB and PEAV respectively. The PEAB had a higher decomposition temperature (T_d) as well as glass transition temperature (T_g) compared to PEAV; albeit, with a lower molecular weight. The polymers’ T_d were in the range of 330 °C–380 °C and the T_g were between 100 °C and 120 °C. The thermal properties of the polymers are in the desirable range for thermoplastic materials used in the packaging, storage, and coating industries. Furthermore, the polymers are susceptible to degradation under acidic conditions in a short period; a property that is highly desirable for degradable polymers. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018 , 56, 2154–2160     

pH-effects in the complex formation of polymers I. Interaction of poly(acrylic acid) with poly(acrylamide)

The effects of polymer concentration, molecular weight of poly(acrylic acid) (PAA), addition of sodium, potassium, ammonium and copper (II) chlorides on the complex formation ability of the system PAA-poly(acrylamide) (PAAM) have been studied in aqueous solutions. The critical pH values of the complexation were determined in different conditions. The complex formation ability of PAAM is compared with other non-ionic polymers. It was shown that an increase in polymers concentration, molecular weight of PAA and ionic strength favours the complexation and shifts the critical pH values to the higher pH region. An addition of CuCl₂ to the mixture of two polymers enhances the complexation drastically due to the formation of triple complexes.     

Preparation and properties of poly(phosphonatoalanes)

Two general types of poly(phosphonatoalanes), [? Al(X)O? P(O)(R)O? ]_n (X = Cl or F, R = alkyl or aryl) and [? Al(OP(O)R₂)O? P(O)(R′)O? ]_n, were prepared and studied. Poly[chloro(phosphonato)alanes] are influsible and have low molecular weights (n = 4–11). Polyfluoro(phosphonato)alanes are fusible and also have low molecular weights, but under certain conditions grow to higher polymers (n = 30–45). Poly[phosphinato(phosphonato)alanes] are fusible and are prepared with high molecular weights (n = 83–340).     

Dilute Solution Properties of Poly(methacrylonitrile-co-styrene) and Poly(acrylonitrile-co-styrene)

Poly(methacrylonitrile-co-styrene) (PMANS) and Poly(acrylo-nitrile- co- styrene) (PANS) having 1:1 composition were prepared with free-radical initiators. The polymers were fractionated into fractions having narrow molecular weight distribution. The dilute solution properties of the fractionated copolymers were studied by light scattering, viscometry, and osmometry in solvents (methyl ethyl ketone, dimethylformamide, and acetone), [n]-M _w and(r²)_w ^l/2?M _w relationships have been established. The validity of the various graphical methods for the determination of Flory′s constant, K _θ were observed.

From the values of the steric factors it was noticed that the copolymer coil of PANS is stiffer than that of PMANS.     

Quantum-chemical justification of possibility of electrochemical polymerization of N2O2 azomethines and their complexes with Cu(II)

Electronic structures of a series of aromatic N₂O₂-azomethines and their complexes with Cu(II) have been simulated by quantum chemistry methods. By analyzing the spin density and the highest occupied molecular orbital structure of the single-electron oxidation products (cation-radicals) of the monomers, we have concluded about possibility of the monomers polymerization to give the electroconductive polymers.     

2,4,6‐Tri(hydroxy)‐1,3,5‐triphosphinine,P3C3(OH)3: The Phosphorus Analogue of Cyanuric Acid

Cyanuric acid (C₃H₃N₃O₃) is widely used as cross‐linker in basic polymers (often in combination with other crosslinking agents like melamine) but also finds application in more sophisticated materials such as in supramolecular assemblies and molecular sheets. The unknown phosphorus analogue of cyanuric acid, P₃C₃(OH)₃, may become an equally useful building block for phosphorus‐based polymers or materials which have unique properties. ¹ Herein we describe a straightforward synthesis of 2,4,6‐tri(hydroxy)‐1,3,5‐triphosphinine and its derivatives P₃C₃(OR)₃ which have been applied as strong π‐acceptor η⁶‐ligands in piano stool Mo(CO)₃ complexes.     

Glass transition and miscibility in blends of two semicrystalline polymers: Poly(aryl ether ketone) and poly(ether ether ketone)

Binary melt‐blended mixtures of two aryl ether ketone polymers (i.e., a new poly(aryl ether ketone) (code name PK99) and poly(ether ether ketone) (PEEK), have been studied. Polymer miscibility in glassy amorphous (or melt) domains has been demonstrated for the binary blend comprising of two aryl‐ether‐ketone‐type semicrystalline polymers. Composition‐dependent, single T_g was observed within full composition range in the PK99/PEEK blends, and the narrow T_g breadth also suggests that the scale of mixing was fine and uniform. To better resolve any possible overlapping T_g's, physical aging was imposed on a comparison set of blend samples for the purpose of improving detectability of overlapped multiple transitions if existing. The result still showed one single T_g. The relative sharp T_g and lack of cloud point transition suggest that the scale of molecular intermixing is good. Phase homogeneity was further confirmed using optical and scanning electron microscopy. The X‐ray diffractograms suggest that isomorphism does not exist in the PK99/PEEK blends and that the crystal forms of the respective polymers remain distinct and unchanged by the miscibility in the amorphous region. © 1999 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 37: 1485–1494, 1999     

Synthesis and photovoltaic properties of novel (X-DADAD)n conjugated polymers with fluorene and phenylene blocks

Novel fluorene- and phenylene-based conjugated polymers with the TBTBT molecular framework consisting of the thiophene (T) and benzothiadiazole (B) building blocks have been synthesized and investigated. It has been demonstrated that the variation of X building blocks with branched side chains in (X-TBTBT)_n-type structures, as well as the introduction of fluorine into the main chain, strongly affects the optical, electronic and physicochemical properties of the obtained polymers. The phenylene-based polymer with a fluorine- loaded TBTBT block achieves a power conversion efficiency of 7% in organic solar cells, which can be further improved by optimizing the active layer morphology.     

2,4,6‐Tri(hydroxy)‐1,3,5‐triphosphinine,P3C3(OH)3: The Phosphorus Analogue of Cyanuric Acid

Cyanuric acid (C₃H₃N₃O₃) is widely used as cross‐linker in basic polymers (often in combination with other crosslinking agents like melamine) but also finds application in more sophisticated materials such as in supramolecular assemblies and molecular sheets. The unknown phosphorus analogue of cyanuric acid, P₃C₃(OH)₃, may become an equally useful building block for phosphorus‐based polymers or materials which have unique properties. ¹ Herein we describe a straightforward synthesis of 2,4,6‐tri(hydroxy)‐1,3,5‐triphosphinine and its derivatives P₃C₃(OR)₃ which have been applied as strong π‐acceptor η⁶‐ligands in piano stool Mo(CO)₃ complexes.     

Ionic conductivity and compatibility studies of blends of poly(methyl methacrylate) and poly(propylene glycol) complexed with LICF3SO3

Stable to atmospheric moisture, adhesive and transparent polymer electrolytes have been prepared by blending poly(methyl methacrylate) (PMMA) with poly(propylene glycol)-425/LiCF₃SO₃ complexes. The blending of the polymers has been achieved by a method developed in our laboratory: free radical polymerization of methylmethacrylate in the polyether/salt matrix. A series of polymer blend complexes varying in PMMA content (up to 20% by weight) and oxygen/metal ratios (25, 16, and 8) have been synthesized and their properties studied. All the samples prepared in this study were found to be optically clear unlike the higher molecular weight poly(propylene glycol)-2000 (PPG-2000) system which required a minimum salt concentration to compatibilize a specific amount of PMMA with PPG. The mechanisms by which the salt holds the otherwise incompatible polymers together in a single phase have been investigated by FT-IR. Our studies show a weak coupling of the ether oxygens in the PPG with the ester groups of the PMMA through the lithium cations. Discrete changes has been observed in the FT-IR spectrum of PMMA when doped with the lithium salt hitherto unnoticed with other dopants. Gel permeation chromatography results of the PMMA samples isolated from the solid electrolytes indicate the molecular weight to vary between 43000 and 121000 with relatively narrow distributions, 1.6?2.0. The ionic conductivities of the polymer blend electrolytes were fairly high (10^?5 S/cm) at room temperature. The PMMA neither significantly influenced the T_g of the blend complexes nor effected the ionic conductivities drastically. The ionic conductivity as a function of temperature followed the empirical Vogel-Tammann-Fulcher equation. The blending of PMMA with PPG/LiCF₃SO₃ complexes was found to impart good adhesiveness to the solid electrolytes while making them stable to atmospheric moisture. © 1992 John Wiley & Sons, Inc.