New telechelic polymers and sequential copolymers by polyfunctional initiator-transfer agents (inifers). XVIII. Epoxy and aldehyde telechelic polyisobutylenes

This article concerns the synthesis and characterization of new epoxy and aldehyde telechelic polyisobutylenes, that is, and . The synthesis of the epoxy derivative was achieved by quantitative epoxidation of α,ω-di(isobutenyl) polyisobutylene with m-chloroperoxybenzoic acid and that of the dialdehyde by quantitative isomerization of the epoxy termini with zinc bromide. Infrared (IR) and ¹H-NMR analysis of these new telechelic polymers and ultraviolet (UV) analysis of the 2,4-dinitrophenylhydrazine derivative of the dialdehyde indicate quantitative conversions and yields, that is, essentially theoretical functionalization (F _n = 1.95 ± 0.05).     

New telechelic polymers and sequential copolymers by polyfunctional initiator-transfer agents (inifers). III. Synthesis and characterization of poly(α-methylstyrene-b-isobutylene-b-α-methylstyrene)

The synthesis of a new glassy-rubbery-glassy triblock copolymer poly(α-methylstyrene-b-isobutylene-b-α-methylstyrene) has been demonstrated. The key to the synthesis was the preparation by inifer method of a perfectly bifunctional polyisobutylene which carries tert-chlorine end groups Cl-PIB-Cl. In conjunction with Et₂AlCl coinitiator, the telechelic Cl-PIB-Cl molecule initiates the polymerization of α-methylstyrene at both ends of the prepolymer. Triblock composition can be controlled by the judicious selection of synthesis conditions; that is, Cl-PIB-Cl molecular weight, α-methylstyrene concentration, and solvent polarity. Theoretical triblock M _n calculated from M _n of Cl-PIB-Cl and triblock overall composition is in excellent agreement with experimental M _n which indicates negligible homopolymer contamination. Extraction with a series of hydrocarbon solvents reveals broad composition distribution. The stress-strain profile of a triblock is similar to that of a poly(styrene-b-butadiene-b-styrene) thermoplastic elastomer of similar composition.     

New telechelic polymers and sequential copolymers by polyfunctional initiator-transfer agents (inifers). LIII. Lithiation of 2,4,4-trimethyl-1-pentene and isopropylidene-capped polyisobutylenes by butyllithiums in the presence of complexing agents

Lithiated isopropylidene-telechelic polyisobutylenes (i.e., PIBs capped with end groups) are most interesting novel intermediates for further transformations, e.g., functionalization, polymerization. This report concerns model lithiation experiments of 2,4,4-trimethyl-1-pentene (TM1P) that guided us toward the subsequent quantitative lithiation of isopropylidene-telechelic PIBs. Thus, lithiation of TM1P with, n-, s-, and t-butyllithium, in the presence of various complexing agents (i.e., TMEDA, t-BuOK, 1,2-DPE, CH₃OCH₂CH₂OCH₃, THF, and 12-crown-4) followed by silylation with Me₃SiCl (for the purpose of quantitation) gave three products: 2(trimethylsilylmethyl)-4,4-dimethyl-1-pentene (TM1P-Si), 2(trimethylsilylmethyl)-4,4-dimethyl-2-pentene (TM2P-Si₂). The relative product composition strongly depends on the BuLi/complexing agent ratio and temperature. Among the different butyllithiums and complexing agents the best overall results were obtained with the s-BuLi/TMEDA combination. Complete lithiation of TM1P with minimum dilithiation was obtained using the molar ratio [s-BuLi]: [TMEDA]: [TM1P] = 2 : 2 : 1. The apparent activation energy of lithiation by s-BuLi/TMEDA was found to be 6.7 ± 0.8 kcal/mol. Guided by TM1P model experiments, quantitative monolithiation of isopropylidene-capped polyisobutylene (including ca. 4% chain and isomerization) was achieved using the molar ratio [s-BuLi] : [TMEDA] : [C? C] = 5 : 4 : 1.     

New telechelic polymers and sequential copolymers by polyfunctional initiator-transfer agents (inifers). II. Synthesis and characterization of α,ω-di(tert-chloro)polyisobutylenes

Detailed understanding of the mechanism of initiation and chain transfer in BCl₃-coinitiated isobutylene polymerization led to the efficient synthesis of symmetric telechelic polyisobutylenes carrying ～CH₂C(CH₃)₂Cl groups at either end of the molecule Cl-PIB-Cl. The synthesis is based on the use of inifers, i.e., bifunctional initiator-transfer agents that effect controlled initiation and propagation in the absence of chain transfer to a monomer. Specifically, the synthesis of Cl-PIB-Cl was achieved by the p-dicumyl chloride/BCl₃/isobutylene/CH₂Cl₂ system. According to the inifer mechanism each Cl-PIB-Cl contains two terminal tertiary chlorines and one phenyl group at the interior of the chains. The structure of this new symmetric telechelic polymer has been established by detailed characterization studies including a sensitive new gel permeation chromatography (UV plus RI) analysis method, ¹H-NMR, kinetic experiments, and chemical derivatization. The Cl-PIB-Cl molecule is a key intermediate for the synthesis of hosts of new materials, e.g., triblock copolymers, α,ω-diolefins, and α,ω-difunctional polymers.     

New telechelic polymers and sequential copolymers by polyfunctional initiator-transfer agents (inifers). VII. Synthesis and characterization of α,ω-di(hydroxy)polyisobutylene

A new telechelic polyisobutylene diol, HO? CH₂? PIB? CH₂? OH, carrying two terminal primary hydroxyl end groups has been prepared from α,ω-di(isobutenyl)polyisobutylene, CH₂?C(CH₃)- CH₂? PIB? CH₂C(CH₃)?CH₂, by regioselective hydroboration followed by alkaline hydrogen peroxide oxidation. Infrared (IR) spectra, ¹H-NMR analysis of the pure and silylated products, and ultraviolet (UV) spectra of phenylisocyanate-treated diols indicate quantitative yields and two ? CH₂OH termini per polyisobutylene chain. The viscosity of HO? CH₂? PIB? CH₂? OH is higher than that of the starting α,ω-diolefin. The telechelic diol prepolymer opens new avenues to the synthesis of many new materials, e.g., polyurethanes.     

New telechelic polymers and sequential copolymers by polyfunctional initiator-transfer agents (inifers). XXX. Synthesis and quantitative terminal functionalization of α,ω-diarylpolyisobutylenes

Novel aromatic-telechelic polyisobutylenes were prepared and characterized: α,ω-diphenylpolyisobutylene, α-phenyl-ω-tolylpolyisobutylene, and α,ωditolylpolyisobutylene. The syntheses involved the preparation of asymmetric telechelic prepolymers (α-phenyl-ω-tert-chloropolyisobutylene and α-tolyl-ω-tert-chloropolyisobutylene) by the minifer method and quantitative alkylation of benzene and toluene by the prepolymer. The terminal aromatic rings of these telechelic polyisobutylenes were quantitatively nitrated, acetylated, and chlorosulfonated and a series of further novel telechelic products was obtained. Characterization of these derivatives provided additional proof for the telechelic structure of the starting prepolymers. The quantitative reduction of nitroaryl-telechelic polyisobutylene by SnCl₂/HCl led to aminoaryl-telechelic polyisobutylene which was used to cure bisphenol-A diglycidyl ether. These new flexible epoxy networks exhibited outstanding heat and hydrolytic stability combined with satisfactory mechanical properties.     

Crystallization behavior of poly(styrene-ethylene) copolymers prepared by sequential polymerization

Polystyrene-ethylene copolymers were prepared by sequential polymerization of styrene and ethylene. The crystallization behaviors of the PSE copolymers were studied by polarized light microscopy, wide angle X-ray diffraction and differential scanning calorimeter. The spherulitic growth rates have a tendency of reduction with increasing of styrene content. The growth rates, the melting points and onset temperatures of melting peaks are lower than those of pure polyethylene. The orthorhombic lattice parameters of relatively low styrene content are slightly larger than those in pure PE and the X-ray diffraction traces are no more typically orthorhombic when the styrene content is relatively high. The DSC analyses on the annealed fractions extracted with temperature gradation elution fractionation revealed that the components in the copolymer could be classified into three types based on the thermal behaviors: styrene ethylene random copolymer, ethylene-predominant copolymer and multi-ethylene segment copolymer.     

New poly(amide-imide) siloxane copolymers by polycondensation

Some new poly(amide-imide) siloxane copolymers have been synthesized by solution polycondensation of some aromatic diamines with siloxanic diacids having preformed imide rings. Two polycondensation techniques were used: polycondensation of aromatic diamines with diacid chlorides and direct polycondensation of aromatic diamines with diacids in the presence of organic phosphites, following the Yamazaki-Higashi phosphorylation technique. In all cases the reactions were carried out using equimolecular amounts of the two monomers, in polar aprotic solvents and inert atmosphere.The obtained compounds were characterized by elemental C, H and Si analysis, solubility tests, IR and ¹H-NMR spectrometry. Thermogravimetric curves were also recorded. All data agree with the proposed structures.     

Study on the conformations in poly(p-chlorostyrene)-endothermic solvent (n-propylbenzene) and poly(p-chlorostyrene)-exothermic solvent(tert-butyl acetate) at theta temperatures by X-ray small-angle scattering

Summary Conformations of linear poly(p-chlorostyrene) (PPCS) in an endothermic solvent (n-propylbenzene) and an exothermic solvent (tert-butyl acetate) at theta temperatures have been investigated by X-ray small angle scattering. By analyzing X-ray small-angle scattering data for the two systems, the determination of molecular parameters and the comparison between an angular dependence of experimental scattering curve and that of theoretical one have been made, with the discussion on the asymptotic behavior of the scattering curve.The values of persistence length and the radius of gyration of a cross section of polymer chain were 10.5–13.0 Å and 3.7 Å for PPCS-n-propylbenzen, and 11.1–13.7 Å and 5.2 Å for PPCS-tert-butyl acetate, respectively.The values of persistence length seem to be little affected in both systems, while those of radius of gyration of a cross section of polymer chain seem to be affected appreciably by the condition whether the system is endothermic or exothermic. The effect of the distribution of the electron density on the cross section is almost equal in both solvents. From the asymptotic behavior of scattering curves, the system of PPCS-n-propylbenzene has the area of interface larger than that of PPCS-tert-butyl acetate. Agreements between theoretical and experimental scattering curves are found over the experimental angular regions. Thus, it is considered that conformations of PPCS in both theta conditions are the same as that of an ideal chain and only a radius of gyration of the cross section of the polymer chain assumes different values in two solvents.

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Zusammenfassung Es wurde die Konformation vom linearen Poly(p-chlorostyrol) (PPCS) im endothermen Lösungsmittel (n-Propylbenzol) und im exothermen Lösungsmittel (tert-Butylacetat) bei den -Temperaturen untersucht. Die Bestimmung des molekularen Parameters, der Vergleich zwischen den Winkelabhängigkeiten der experimentellen und theoretischen Streukurven und die Diskussion über das asymptotische Verhalten der Streukurven wurden für die beiden Systeme durch Analyse der Röntgenkleinwinkelstreuungsdaten durchgeführt.Die Werte von Persistenzlängen und Querschnittsstreumassenradien waren 10.5–13.0 Å und 3.7 Å für PPCS-n-Propylbenzol, bzw. 11.1–13.7 Å und 5.2 Å für PPCS-tert Butylacetat.Es scheint, daß kein Einfluß auf die Persistenzlängen in den beiden Systemen existiert, während ein solcher auf die Querschnittsstreumassenradien der Polymerknäuel festzustellen ist, je nachdem das System endotherm oder exotherm ist. Die Verteilung der Elektronendichte hat die gleiche Wirkung auf den Querschnitt in den beiden Systemen.Nach dem asymptotischen Verhalten der Streukurven hat das System von PPCS-n-Propylbenzol die größere innere Oberfläche als die von PPCS-tert Butylacetat. Die Übereinstimmung zwischen den experimentellen und theoretischen Streukurven wird innerhalb der experimentellen Winkelbereiche festgestellt. Hieraus wird geschlossen, daß die Konformationen des PPCS unter Thetabedingungen dieselben sind, die Knäuel ideale Knäuel sind und nur die Werte von Querschnittsstreumassenradien der Polymerknäuel in den beiden Lösungsmitteln differieren.

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With 10 figures and 1 table     

Block copolymers of telechelic poly(phenylene sulfide) and semiaromatic thermotropic liquid crystalline polyester segments

We report the synthesis and characterization of copolymers comprising poly(phenyl sulfide) (PPS) blocks and semiaromatic thermotropic liquid crystalline polymer (TLCP) blocks. The copolymers, synthesized by melt-transesterification of dicarboxy-terminated poly(phenylene sulfide) with poly(ethylene terephthalate-co-oxybenzoate) (PET/OB), were characterized using Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), X-ray diffraction (XRD), and polarized light optical microscopy (PLOM). The crystallizability and liquid crystalline properties of the copolymers are greatly influenced by the extent of interchange reactions, the mole percent of oxybenzoate with respect to the PET, the PPS : PET/OB weight ratio, and the reaction time. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 2707–2713, 1998     

New electrochemically synthesized copolymers: poly(difluorenyl-ethylenes)

Synthesis and cyclic voltammetry data of novel copolymers containing difluorenyl-ethylene units in the conjugated backbone are reported.     

New architectures of poly(ethylene glycol) and poly(methylthiirane) in block copolymers

Two synthetic ways were experimented to prepare new architectures of block copolymers made of poly(ethylene glycol) (PEG) and poly(methylthiirane). The coupling of both blocks conveniently end-capped as well as anionic polymerization of methylthiirane initiated by PEG-thiols gave readily the copolymers. Their characterization by ¹H NMR, SEC and IR confirmed the expected structures.     

Glass bead grafting with poly(carboxylic acid) polymers and maleic anhydride copolymers

Glass beads were etched with acids and bases to increase the surface porosity and the number of silanol groups that could be used for grafting materials to the surfaces. The pretreated glass beads were functionalized using 3‐aminopropyltriethoxysilane (APS) coupling agent and then further chemically modified by reacting the carboxyl groups of carboxylic acid polymers with the amino groups of the pregrafted APS. Several carboxylic acid polymers and poly(maleic anhydride) copolymers, such as poly(acrylic acid) (PAA), poly(methacrylic acid) (PMA), poly(styrene‐alt‐maleic anhydride) (PSMA), and poly(ethylene‐alt‐maleic anhydride) (PEMA) were grafted onto the bead surface. The chemical modifications were investigated and characterized by FT‐IR spectroscopy, particle size analysis, and tensiometry for contact angle and porosity changes. The amount of APS and the different polymer grafted on the surface was determined from thermal gravimetric analysis and elemental analysis data. Spectroscopic studies and elemental analysis data showed that carboxylic acid polymers and maleic anhydride copolymers were chemically attached to the glass bead surface. The improved surface properties of surface modified glass beads were determined by measuring water and hexane penetration rates and contact angle. Contact angles increased and porosity decreased as the molecular weights of the polymer increased. The contact angles increased with the hydrophobicity of the attached polymer. The surface morphology was examined by scanning electron microscopy (SEM) and showed an increase in roughness for etched glass beads. Copyright © 2007 John Wiley & Sons, Ltd.     

Synthesis of amphiphilic poly(methyl methacrylate‐ b‐ethylene oxide) copolymers from monohydroxy telechelic poly(methyl methacrylate) as macroinitiator

The synthesis of well‐defined poly(methyl methacrylate)‐block‐poly(ethylene oxide) (PMMA‐b‐PEO) dibock copolymer through anionic polymerization using monohydroxy telechelic PMMA as macroinitiator is described. Living anionic polymerization of methyl methacrylate was performed using initiators derived from the adduct of diphenylethylene and a suitable alkyllithium, either of which contains a hydroxyl group protected with tert‐butyldimethylsilyl moiety in tetrahydrofuran (THF) at ?78 °C in the presence of LiClO₄. The synthesized telechelic PMMAs had good control of molecular weight with narrow molecular weight distribution (MWD). The ¹H NMR and MALDI‐TOF MS analysis confirmed quantitative functionalization of chain‐ends. Block copolymerization of ethylene oxide was carried out using the terminal hydroxyl group of PMMA as initiator in the presence of potassium counter ion in THF at 35 °C. The PMMA‐b‐PEO diblock copolymers had moderate control of molecular weight with narrow MWD. The ¹H NMR results confirm the absence of trans‐esterification reaction of propagating PEO anions onto the ester pendants of PMMA. The micellation behavior of PMMA‐b‐PEO diblock copolymer was examined in water using ¹H NMR and dynamic light scattering. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 2132–2144, 2008     

Inorganic coordination polymers. VIII. Cobalt(II) and zinc(II) phosphinate polymers and copolymers

The preparation, properties, x-ray powder patterns, and TGA curves are given for cobalt(II) dimethyl-, methylphenyl- and diphenylphosphinate. The polymeric character of cobalt(II) methylphenylphosphinate is demonstrated by its colligative properties and melt indexes. These cobalt(II) phosphinates along with hybrid copolymers of zinc(II) or cobalt(II) were prepared by the reaction of the metal acetate with the appropriate phosphinic acid or mixture of phosphinic acids. A consideration of the hybrid copolymers leads to the conclusion that both the zinc(II) and cobalt(II) dimethyl- and diphenylphosphinates are likewise polymeric. Thermal stability is discussed in terms of the structures suggested, and it is shown that crystallinity is related to polymer symmetry.     

Synthesis and characterization of new telechelic poly(phenyleneoxide)s

New well-defined telechelic poly(phenyleneoxide)s (PPO's) were synthesized from 4-bromo-2,6-dimethylphenol and bi-phenolic compounds through phase transfer catalyzed aromatic nucleophilic substitution polymerization. Bisphenol-A (BPA), 4,4^′-biphenol (BP), hydroquinone (HQ) and 2,6-dihydroxynaphthalene (DHN) were employed as telechelic units. The composition analysis by proton-nuclear magnetic resonance (¹H-NMR) spectroscopy revealed that DHN was highly reactive compared to BPA and HQ, whereas BP was un-reactive in the polymerization process. The number average repeating unit (n) in telechelic PPO was estimated as n=17-19 and n=17-20 for DHN and BPA (or HQ), respectively. The reactivity of the bi-phenolic in PPO synthesis are confirmed as DHN > HQ ∼ BPA ? BP. The molecular weight determination by gel permeation chromatography (GPC) and viscosity method suggest that the molecular weight of PPO decreased drastically with increasing amount of bi-phenolic units in the feed. The GPC chromatogram of PPO showed a bi-modal distribution, clearly indicative of formation of two different types of molecular weight chains, whereas the telechelic polymers have a mono-modal distribution with a narrow polydispersity. Thermal analysis by differential scanning calorimetry revealed that telechelic polymers are highly amorphous, like PPO, and no crystallization or melting peaks were observed in the heating/cooling cycles.