The chemistry of THPC–urea polymers and relationship to flame retardance on wool and wool–polyester blends. II. Relative flame-retardant efficiency on wool,polyester, and wool-polyester blends

Optimum flame retardance in THPC-urea-type formulations was achieved by approximately 1—0.9 THPC-urea mole ratio and slow urea addition. A phosphonium salt structure is more efficient in flame retarding 100% wool and wool-polyester blends than a phosphine oxide structure. Both structures are equivalent in flame retarding 100% polyester. It is considered probable that a vapor-phase mechanism is predominant in the phosphorus-based flame retardancy of wool, whereas a mixed solid-vapor phase mechanism operates for 100% polyester.     

Wholly aromatic polyamide-hydrazides. IV. Structure–property relationships for polymers containing p-phenylene and m-phenylene units

A series of wholly aromatic polyamide-hydrazides was investigated in order to acquire clear understanding of the influence exerted by controlled structural variations in these polymers upon some of important properties, such as chain flexibility, membrane permselectivity, and thermal as well as thermo-oxidative stability. For that reason, the content of para and meta phenylene units was varied within this series so that the changes in the latter were 12.5 mol % from polymer to polymer, starting from an overall content of 0–50 mol %. The polymers were prepared by a low-temperature solution polycondensation reactin of p-aminobenzhydrazide (ABH) and terephthaloyl chloride (TCI), isophthaloyl chloride (ICI), and their appropriate combinations in N,N-dimethylacetamide (DMA) as solvent and all of these preparations were monitored viscometrically in order to prepare the products with as similar as possible average molecular weights. Polymer structures were characterized by elemental analysis, infrared spectrometry, and ¹³C NMR spectroscopy, while their molecular weights were determined by light scattering and dilute-solution viscometry. Polymer properties were evaluated by solution viscometry, reverse osmosis tests, and thermal gravimetric analysis. The results obtained during the preparation of these materials, their subsequent structural characterization, and their property evaluations are discussed. They clearly indicate that substitution of m-phenylene units for p-phenylene ones within this polymer series led to an increase in polymer chain flexibility (from what is usually referred to as semiflexible or semirigid to typically flexible macromolecules), disrupted selectivity of the asymmetric thin membranes under reverse osmosis conditions and decreased stability at elevated temperatures in inert as well as in oxidative atmospheres.     

Small band gap conjugated polymers based on thiophene–thienopyrazine copolymers

In this study, five small band gap thiophene ( TH )–thienopyrazine ( TP ) conjugated copolymers were synthesized by Stille‐coupling reaction. The polymer structures consisted of one to four thiophene rings with the TP of different side groups provided a systematical investigation on the structure–electronic property relationship. The absorption maxima of the polymer films decreased from 850 to 590 nm as the thiophene moieties increased from thiophene to quaterthiophene. The optical and electrochemical band gaps of the studied poly[2,3‐didodecyl‐5‐(thiophen‐2‐yl)thieno[3,4‐b]pyrazine] ( PTHTP‐C12 ) were 0.97 and 0.78 eV, respectively, indicating a significant intramolecular charge transfer. The theoretical geometry and electronic properties of the TH ‐ TP copolymers by the density functional theory at the B3LYP level and 6‐31G(d) basis set suggested that the bond length alternation enlarged with enhancing the thiophene content and resulted in the variation on the polymer band gap. The relatively small theoretical effective mass of poly( TH ‐alt‐ TP ) also indicated its potential applications for field transistor applications. Our study demonstrates the tunable electronic properties of small band gap copolymers by the thiophene content and the resulted geometry variation. Such polymers could be potentially used for near‐infrared electronic and optoelectronic devices. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 5872–5883, 2007     

Synthesis and photoluminescence behaviors of anthracene‐layered polymers

Novel anthracene‐layered polymers containing fluorescence quenchers such as ferrocene and nitrobenzene units at the polymer termini were designed and synthesized. Their optical properties were investigated in detail. The photoluminescence spectra of the polymers were featureless without vibrational structures, indicating that the anthracenes are effectively interacting each other in a single polymer chain in the excited state. Fluorescence emission from the layered anthracene units was effectively quenched by the aromatic units at the polymer termini owing to energy and electron transfer through a single polymer chain. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 2815–2821     

Organometallic polymers. XXIX. Synthesis and characterization of ferrocene-containing siloxane polymers from bis(dimethylamino)silane–disilanol condensation

A new monomer, 1,1′-bis(dimethylaminodimethylsilyl)ferrocene, was synthesized by two routes and polymerized with three aryl disilanols: dihydroxydiphenylsilane, 1,4-bis(hydroxydimethylsilyl)benzene, and 4,4′-bis(hydroxydimethylsilyl)biphenyl, yielding three different polysiloxanes. Melt polymerizations carried out at 1 torr pressure and 100°C resulted in the highest molecular weight polymers. Intramolecular cyclization competed with intermolecular chain extension in polymerization of the bis(aminosilane) with dihydroxydiphenylsilane, resulting in isolation of a bridged derivative, 1,3,5-trisila-2,4-dioxa-1,1,5,5-tetramethyl-3,3-diphenyl[5]ferrocenophane. Cyclization did not compete significantly during the formation of polymers from this bisaminosilane and the two remaining diols, as evidenced by higher yields and greater molecular weights. These polymers could be cast as tough flexible films, and fibers could be drawn from their melts. TGA and DSC data showed the polymer formed from 1,1′-bis(dimethylaminodimethylsilyl)ferrocene and 1,4-bis(hydroxydimethylsilyl)benzene to be at least as thermally stable as an arylene siloxane polymer which differed from the ferrocenylsiloxane structure only in the replacement of the ferrocene moiety with a p-substituted phenylene linkage. The ferrocene-containing polymers were generally hydrolytically stable under conditions of refluxing THF–H₂O(10 : 1) for 1 hr. The polymer-forming reaction was found to follow second-order kinetics, and the specific rate constants for formation of two of the polymers were measured.     

Liquid‐crystalline organic–inorganic hybrid polymers with functionalized silsesquioxanes

Liquid‐crystalline (LC) hybrid polymers with functionalized silsesquioxanes with various proportions of LC monomer were synthesized by the reaction of polyhedral oligomeric silsesquioxane (POSS) macromonomer with methacrylate monomer having an LC moiety under common free‐radical conditions. The obtained LC hybrid polymers were soluble in common solvents such as tetrahydrofuran, toluene, and chloroform, and their structures were characterized with Fourier transform infrared, ¹H NMR, and ²⁹Si NMR. The thermal stability of the hybrid polymers was increased with an increasing ratio of POSS moieties as the inorganic part. Because of the steric hindrance caused by the bulkiness of the POSS macromonomer, the number‐average molecular weight of the hybrid polymers gradually decreased as the molar percentage of POSS in the feed increased. Their liquid crystallinities were very dependent on the POSS segments of the hybrid polymers behaving as hard, compact components. The hybrid polymer with 90 mol % LC moiety (Cube‐LC90) showed liquid crystallinity, larger glass‐transition temperatures, and better stability with respect to the LC homopolymer. The results of differential scanning calorimetry and optical polarizing microscopy showed that Cube‐LC90 had a smectic‐mesophase‐like fine‐grained texture. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 4035–4043, 2001     

Syntheses and reactions of functional polymers. XLVI. Preparation and reactions of N-benzyloxyisomaleimide–styrene copolymer

Polymerization of N-benzyloxymaleimide(I) was attempted to obtain a polymer with the N-hydroxysuccinimide unit in the chain. In the light of infrared and NMR data the compound reported by Ames as N-benzyloxymaleimide is N-benzyloxyisomaleimide (III). Homopolymerization of III did not give polymer. Copolymerization of III with styrene was carried out in dioxane at 70°C. A strong alternation tendency like that of maleimides was observed. Monomer reactivity ratios and Q-e values were determined. Copolymer having the isoimide structure showed infrared absorptions at 1815 and 1675 cm^?1 in the carbonyl region. The copolymer was isomerized to N-benzyloxymaleimide type copolymer and debenzylated to N-hydroxymaleimide type copolymer. An insoluble copolymer was prepared by using divinylbenzene as a crosslinking agent and was converted to N-acetoxymaleimide type copolymer, which was used as an insoluble acetylating agent.     

Ethynylene‐containing donor–acceptor alternating conjugated polymers: Synthesis and photovoltaic properties

Four ethynylene‐containing donor‐acceptor alternating conjugated polymers P1 – P4 with 2,5‐bis(dodecyloxy) substituted phenylene or carbazole as the donor unit and benzothiadiazole (BTZ) as the acceptor unit were synthesized and used as donor polymers in bulk heterojunction polymer solar cells. The optical, electrochemical, and photovoltaic properties of these four polymers with the ethylene unit located at different positions of the polymer chains were systematically investigated. Our results demonstrated that absorption spectra and the HOMO and LUMO energy levels of polymers could be tuned by varying the position of the ethynylene unit in the polymer chains. Photovoltaic devices based on polymer/PC₇₁BM blend films spin coated from chloroform and dichlorobenzene solutions were investigated. For all four polymers, open circuit voltages (V_oc) higher than 0.8 V were obtained. P4 , with ethynylene unit between BTZ and thiophene, shows the best performance among these four polymers, with a V_oc of 0.94 V, a J_sc of 4.2 mA/cm², an FF of 0.40, and a PCE of 1.6%. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013     

Carborane polymers. IV. Polysiloxanes

Carboranes attached to silicon through straight-chain alkyl groups were prepared and characterized for thermal stability by TGA and molecular weight change on heating. The monomers for these polymers were prepared generally by platinum-catalyzed addition of a silylhydride to an alkenyl or dialkenyl carborane. Polymerization was effected by hydrolysis-condensation of chlorosilanes, ring opening of cyclosiloxanes, and condensation of alkoxy and chlorosilanes. Two types of polymer structures were prepared, one contained m-carborane in the chain backbone, the other contained o-carborane as pendant alkylcarborane groups. Both types were obtained as elastomers; however, higher proportions of carborane in the polymers reduced elasticity and finally resulted in nonelastomers. TGA of the backbone carborane siloxane polymer indicated degradation at 370°C. in nitrogen and at 235°C. in air. Chain scission, as determined by molecular weight decrease, was observed on heating in nitrogen at 350°C. TGA of the pendant carborane siloxane polymer indicated that degradation in nitrogen and in air occurred at greater than 400°C. However, chain scission, as determined by molecular weight decrease, was observed upon heating at 300°C. in nitrogen.     

Dendronized polymers via Diels–Alder “click” reaction

A modular approach toward the synthesis of polymers containing dendron groups as side chains is developed using the Diels–Alder “click” reaction. For this purpose, a styrene‐based polymer appended with anthracene groups as reactive side chains was synthesized. First through third‐generation polyester dendrons containing furan‐protected maleimide groups at their focal point were synthesized. Facile, reagent‐free, thermal Diels–Alder cycloaddition between the anthracene‐containing polymer and latent‐reactive dendrons leads to quantitative functionalization of the polymer chains to afford dendronized polymers. The efficiency of this functionalization step was monitored using ¹H and ¹³C NMR spectroscopy and FTIR and UV–vis spectrometry. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 410–416, 2010     

Acrylamide–itaconic acid superabsorbent polymers and superabsorbent polymer/mica nanocomposites

Superabsorbent polymer acrylamide (AM)/itaconic acid (IA) and its nanocomposite were synthesized by redox polymerization in an aqueous solution of both monomers with mica used as an inorganic additive. The influences of IA concentration, mica content, and crosslinker concentration on the water absorption and physical properties of the superabsorbent polymer and its nanocomposite were examined. Water absorbency in artificial urine by the synthesized copolymers, and the gel strength of the superabsorbent copolymers and their nanocomposites, were tested with loads of 0.28 or 0.70 psi. Transmission electron micrographs and X‐ray diffraction confirmed that the polymer chains were successfully intercalated into the silicate layers in the mica. The water absorbency and the artificial urine absorbency of the composite with an AM‐to‐IA mole ratio of 95:5, 0.2% mol N‐MBA, and 5% w/w mica were 748 ± 5 and 76 ± 2 g g^?1, respectively, whilst the neat copolymer achieved only 640 ± 7 and 72 ± 2 g g^?1 in water and artificial urine, respectively. The viscoelastic behavior suggested that the swollen gel of the nanocomposites exhibited mechanical stability and elasticity. Copyright © 2009 John Wiley & Sons, Ltd.     

Proteins and polymers

Proteins, chain molecules of amino acids, behave in ways which are similar to each other yet quite distinct from standard compact polymers. We demonstrate that the Flory theorem, derived for polymer melts, holds for compact protein native state structures and is not incompatible with the existence of structured building blocks such as alpha helices and beta strands. We present a discussion on how the notion of the thickness of a polymer chain, besides being useful in describing a chain molecule in the continuum limit, plays a vital role in interpolating between conventional polymer physics and the phase of matter associated with protein structures.     

Exactly alternating silarylene–siloxane polymers. VII. Thermal stability and degradation behavior of p-silphenylene–siloxane polymers with methyl,vinyl, hydrido,and/or fluoroalkyl side groups

The thermal stability and degradation behavior of a series of nine different exactly alternating silphenylene-siloxane polymers which contained methyl, vinyl, hydrido, 3,3,3-trifluoropropyl, and tridecafluoro-1,1,2,2-tetrahydrooctyl side groups, or their combinations, were investigated by dynamic and isothermal gravimetric analyses in air and in nitrogen. Two distinctly different mechanisms were observed in these atmospheres: a complex multi-step weight loss process in air and a single-step process in nitrogen. In nitrogen all polymers produced black, insoluble, highly stable degradation residues which were characterized by high carbon content. In contrast, in air the nonfluorine containing polymers degraded to pure silica, while the fluoroalkyl substituted polymers may have formed fluorosilicates of unspecified structures. There appears to be no significant molecular weight effect on the thermal stability of these polymers, at least not above an M _w value of about 35,000. Isothermal investigations indicate that 300°C in air and 350°C in nitrogen may be possible upper use temperatures for the methylvinyl substituted, exactly alternating silphenylene–siloxane polymers for extended periods of time. A strong thermostabilizing effect by vinyl side groups on the degradation behavior of these polymers was established. The extent of stabilization depends on the content of vinyl units, but it can already be clearly seen at the 5 mol % vinyl level, and it increases exponentially with increasing vinyl concentration. In contrast to this behavior, by comparison with the parent all-methyl substituted, exactly alternating silphenylene–siloxane polymers, the hydrido and fluroalkyl side groups reduce overall polymer thermal stability in terms of the degradation onset temperature, the temperature for 50% weight loss, and the amount of degradation residue. The presence of these groups also extends the later stages of the degradation processes to higher temperatures. Based on these and previous results, an order of stability is proposed as a function of the type of the substituent side groups for the thermal degradation of these polymers.     

Structure of diepoxide–diamine network polymers. II. Soluble chemical species

Gel permeation chromatography has been used to separate diepoxide–diamine oligomers, produced at a variety of stoichiometric ratios, into individual chemical species. Probability theory has been applied to calculate expressions for the amounts of each of these compounds and close agreement has been found with the experimental results. In conjunction with previous conclusions, this provides compelling evidence in favor of a purely random reaction mechanism, contrary to the inhomogeneous network-forming mechanism suggested by other workers. The effect of adding an inert diluent prior to reaction has been investigated and it is evident that the fraction of intramolecularly formed bonds increases as the concentration of polymer decreases.     

Interaction of inorganic salts with polar polymers. II. Infrared studies of polymer–inorganic nitrate systems

Certain inorganic nitrate salts are quite soluble in the polymers studied, namely, cellulose acetate, poly(vinyl acetate), poly(vinyl alcohol), poly(methyl methacrylate), and poly(methyl acrylate). Large effects upon the glass-transition temperature were observed in those systems where the transition could be readily measured. Large shifts in the infrared spectra of both the inorganic nitrate salts and in the polymer carbonyl and ester ether frequencies have been observed. These observations have been interpreted in terms of complex formation between these polymers and salts in the solid state. The proposed structure of the complex explains the nature of the infrared shifts both for the nitrate salts and the polymers as well as explaining the concentration effects observed. Effects of the solvating environment upon the salt and polymer spectra remain unexplained. The large glass-transition effects are a result of the degree of solubility of the salts in the polymers and the interactions between them. However, the reason why, in some cases, the change in the transition temperature as a function of concentration goes through a maximum is unclear.     

Esca applied to polymers. XXIII. RF glow discharge modification of polymers in pure oxygen and helium–oxygen mixtures

The oxidation of polyethylene, polypropylene, and polystyrene by exposure to plasmas excited in pure oxygen and helium–oxygen mixtures at low power levels has been studied. A detailed curve resolution procedure is outlined, and the rate of oxidation is shown to be a strong function of the polymer structure for pure oxygen plasmas, as is the composition of the oxidized layer; this is not the case, however, for oxidation effected by helium–oxygen mixtures. It seems likely, from a consideration of the available data, that the oxidation is confined to the outermost monolayer and is initiated by a crosslinking mechanism that involves oxygen-containing functionalities.     

Multidimensional benzobisoxazole rigid-rod polymers. II. Processing,characterization, and morphology

A high-torque rheometer was used to facilitate the polycondensation of 4-[5-amino-6-hydroxybenzoxazol-2-yl]benzoic acid (ABA) with trimesic acid and 1,3,5,7-tetrakis(4-carboxylatophenyl)adamantane to yield two- and three-dimensional benzobisoxazole polymers, respectively. Although the resultant polymer dopes exhibited improved homogeneity compared to polymer dopes previously prepared in glassware, improved polymer solution viscosities were not achieved. Fibers spun from the two- and three-dimensional polymers did not show a significant increase in compressive strength compared to fibers of the linear or one-dimensional benzobisoxazole polymer derived from the homopolymerization of ABA. Morphological studies of the polymer fibers and films by wide-angle X-ray scattering and scanning electron microscopy strongly indicated more lateral disorder and a more isotropic character for the three-dimensional structures compared to the one-dimensional structures. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35 : 3457–3466, 1997     

A study of surface dynamics of polymers. II. Investigation by plasma surface implantation of fluorine–containing moieties

Macromolecules at the surface of a polymeric solid have considerable mobility, and the specific arrangement of functional groups of macromolecules at the surface is dictated by the environmental conditions in which the surface is placed. Consequently, the change of environmental conditions, such as immersion in water or placement in a biological surrounding, could cause a cosiderable degree of change in the surface characteristics of a polymer from those evaluated in the laboratory against ambient air. The mobile nature of a polymer surface can be investigated by surface-implanting fluorine-containing moieties, mainly—CF₃, by the plasma implantation technique and following the disappearance and reappearance of fluorine atoms on the surface. The disappearance rates (based on the immersion time in water at room temperature) of ESCA F_1s signals, the decay rates of (advancing) contact angle of water, and the recovery of these values on heat treatment of water-immersed samples were measured as a function of crystallinity of polymer samples (at three levels of crystallinity) for poly(ethylene terephthalate) and nylon 6.     

Structure–property relationships of ionene polymers

The synthesis of new ionenes was accomplished by the reaction of novel diamines and dihalides. A new class of crosslinkable ionenes was made possible by the synthesis of tertiary diamines with acrylate functionality, generated ultimately from diepoxides and secondary amines. Other tertiary diamines were produced by endcapping of diols with tolylene diisocyanate, followed by reaction with N,N-dimethylethanolamine and also termination of living poly(tetrahydrofuran) polymer with dimethylamine. New dihalides were produced by the opening of diepoxides with ω-bromoacids. These diamines and dihalides underwent Menschutkin reactions providing novel ionenes for structure–property relationship studies. Correlations were drawn concerning amine nucleophilicity, dihalide nucleofugascity, and molecular weight. Stress–strain and thermal data reflected the effects of ionic domains and large flexible segments in the polymers. Also considered were the electrical conductivity, moisture–vapor transmission, and oxygen permeability of these materials.     

Moisture‐mediated intrinsic self‐healing of modified polyurethane urea polymers

Functional materials having the ability to self‐heal cracks or scratches after damage are of great interest for a huge scope of applications. Herein, we report a self‐healing polyurethane urea‐based material with implemented 1‐(2‐aminoethyl) imidazolidone (UDETA) as a chain terminating molecule and for hydrogen bond network formation. Both, UDETA content and moisture affected the self‐healing process. The reversible change in the materials properties was proven by detailed analyses of hardness and thermomechanical behavior in dependence of the water uptake of the samples. FT‐IR analysis revealed that water is able to act as a plasticizer interrupting hydrogen bonding interactions within the polymer network and thus, influencing glass transition temperature and hardness of the samples. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018 , 56, 537–548.