Polymers with sulfinyl and oxyethylene constitutional units as catalysts of nucleophilic substitution reactions

The catalytic activity of polystyrene- and polyphosphazene-supported monosulfoxides and oligo(oxyethylene)s was investigated in the Williamson alkylation of sodium phenoxide with 1-bromooctane in 1,4-dioxane at 75°C. Polymer-supported monosulfoxides are less efficient than low-molecular-weight species. Polymer-supported oligo(oxyethylene)s with pseudo-crown-ether structures show a polymer effect, which may even be stressed by the presence of onium units in the side chains.     

Liquid crystalline polymers, 8. Structurally ordered thermotropic polyesters of glycol ethers

A series of polysters based on a triad aromatic ester mesogenic unit but containing different poly(alkylene oxide) flexible spacers in the main chain was prepared and its properties examined. The flexible spacers consisted of poly(alkylene oxide)s of varying lengths based on either oligomers of ethylene oxide or propylene oxide. The spacer types, lengths and distributions were found to strongly affect the mesophase and melting behaviors of the polymers. Polymers with spacers having more than 10 units were not liquid crystalline, whereas those of shorter length exhibited mesophase properties. The polymers containing spacers with two, three, or four oxyethylene units showed two mesophases, and the textures of their mesophases suggested that both smectic and nematic phases were formed.     

Crystallinity of methylene-oxyethylene-methylene triblock oligomers. A study of the C21, C26 and C30 di-n-alkyl ethers of pentadecaethylene glycol

Block oligomers of general formula H(CH₂)_nO(CH₂CH₂O)₁₅(CH₂)_nH, where n = 21, 26 and 30, were prepared. Both the oxyethylene and the alkyl blocks are homogeneous. Examination of their crystalline structure (by X-ray scattering, Raman and IR spectroscopy and differential scanning calorimetry) reveals two characteristic forms: type II formed on slow crystallisation of oligomers with n = 21 or 26, and type III b formed on rapid crystallisation of oligomers with n = 26 or 30. Structure II has unfolded chains in a completely crystalline layer structure, with helical oxyethylene blocks and planar zig-zag alkyl blocks. Structure III b has once-folded chains in a partly crystalline layer structure, with non-crystalline planar zig-zag oxyethylene blocks and crystalline planar zig-zag alkyl blocks.     

The adsorption of divalent metallic ions by polyamides having oligo(oxyethylene) segments in the repeating unit

Polyamides 1a – d having 1 to 4 oxyethylene units in the repeating unit were prepared from α-(2-aminoethyl)-ω-aminooligo(oxyethylene)s ( 2a – d ) and sebacoyl chloride. The adsorption of divalent metallic ions by the polyamides 1 was found to be in general in the order: Cu²⁺ > H ? Zn²⁺ ～ Cd²⁺. Polyamides with longer oligo(oxyethylene) units exhibit better adsorption capacities. The adsorption of Hg²⁺ by a polyamide with four oxyethylene units in the repeating unit follows a Langmuir adsorption isotherm, with a binding constant of K = 146 1 per mol of repeating units and a maximum Hg²⁺ adsorption of w_s = 0,36 mol per mol of repeating units.     

Crystallinity of methylene-oxyethylene-methylene triblock oligomers derived from nonaethylene glycol

Block oligomers of general formula CH₃(CH_2)nO[CH₂CH₂O]₉(CH_2)nCH₃ where n = 0 to 25 have been prepared. All blocks are monodisperse. Examination of their crystallinity (by differential scanning calorimetry, X-ray scattering, infra-red and Raman spectroscopy) shows that, within defined limits (n > 9, crystallisation temperature high), the block oligomers can crystallise completely. A likely structure is 7/2 helical monoclinic oxyethylene blocks and planar zigzag low density methylene blocks, with the oxyethylene helices normal to the lamella end-planes and the methylene chains titled.     

ABA triblock comb copolymers with oligo(oxyethylene) side chains as matrix for ion transport

ABA triblock copolymers consisting of two terminal blocks (A) of comb-like polymethacrylate with oligo(oxyethylene) side chains (on the average eight oxyethylene units per side chain) and a middle block B of polystyrene were synthesized by anionic polymerization. The ratios A/B were varied, and the respective polymers characterized by ¹H and ¹³C NMR, gel permeation chromatography (GPC) and differential scanning calorimetry (DSC). The polymers were then solution-cast from tetrahydrofuran solutions of lithium perchlorate, and the homogeneous, solvent-free polymer electrolyte systems tested for their thermal characteristics (DSC) and conductivity. The inclusion of a polystyrene block in the comb-like polymethacrylate electrolyte vastly improves their film-forming and mechanical properties, but also lowers the conductivity. Addition of dimethyltetraethyleneglycol (2,5,8,11,14-pentaoxapentadecane) enhances the ion conduction which can reach values of 10^?4 Ω^?1 · cm^?1 at 70°C, depending on salt and styrene content.     

Supramolecular structures of poly(p-phenylenes) with oxyethylene side chains and their mixtures with lithium salts

A series of poly(p-phenylenes) with linear and branched oxyethylene side chains was synthesized. Microphase separation in the solid state causes polymers with linear side chains to form supramolecular structures, which consist of main chain layers separated by an amorphous side chain matrix. If mixed with lithium salts such as lithium triflate (LiOTf) or lithium bis(trifluoromethanesulfone)imide (LiNTf), the polymers form solid solutions. The experimental data suggest that the layered structures undergo a one-dimensional swelling in the direction perpendicular to the main chain layers when blended with LiOTf and that this salt is only incorporated into the side chain matrix. The observed melting point depression in polymer-LiNTf mixtures is explained by the assumption that the salt species are incorporated both into the side chain and the main chain microphase.     

Adsorption of fibrinogen on to polystyrene latex coated with the non-ionic surfactant, poloxamer 338

We have measured the isothermal adsorption of 125I-fibrinogen on to polystyrene latex (PSL), which was prepared without surfactants, and on to PSL with an adsorbed coat of poloxamer 338 (an A-B-A block copolymer where A is poly(oxyethylene) and B is poly(oxypropylene]. The plateau adsorption of fibrinogen, at 310 K, was significantly lower on to latex coated with poloxamer 338. Previous studies have shown that poloxamer 338-coated PSL is cleared less avidly than uncoated PSL by cells of the mononuclear phagocytic system (MPS). Our findings are quantitative evidence in support of the theory that the uptake of colloids by the MPS can be related to the interfacial adsorption of opsonic proteins.     

Crystallinity of uniform triblock oxyethylene/methylene/oxyethylene (EmCnEm) oligomers studied by X-ray diffraction,differential scanning calorimetry and Raman spectroscopy

Uniform triblock oligomers with a central methylene block and outer oxyethylene blocks terminated by methoxy groups, CH₃(OCH₂CH₂)_mO(CH₂)_n(OCH₂CH₂)_mOCH₃ (E_mC_nE_m), were prepared and studied in the solid state by X-ray diffraction, differential scanning calorimetry and Raman spectroscopy. Both fully crystalline and partly-crystalline structures were found, with chains in wholly trans-planar and mixed-trans-planar/helical conformations. Comparison is made with previous results for triblock oligomers of type C_nE_mC_n and diblock oligomers of type C_nE_m.     

1H and 13C NMR determination of the hydroxy end-groups in poly(oxypropylene)s

¹H and ¹³C NMR signals of tri(propylene glycol) and of its benzoate and phenyl urethane were assigned by means of 1D and 2D NMR methods such as super-selective long-range INEPT, H-H COSY, H-C COSY and H-H-C RCT spectra. Both ¹H and ¹³C NMR were used as methods for the determination of primary and secondary hydroxy end-groups and of their degree of conversion. ¹³C NMR was found to be a reliable and universal method of end-group determination even for cases where ¹H NMR fails due to the presence of water in the sample or to the nature of the reactant. The results are applied to the analysis of poly(oxypropylene)s with two or three hydroxy end-groups and their derivatives.     

Poly(ethylene terephthalate): A solid state condensation process, 2. Copolymerization

Copolyesters of poly(ethylene terephthalate) containing 0,95 to 14,2 mole-% di(oxyethylene)oxy units are prepared in a solid state condensation process. A low molecular weight prepolymer with reactive end groups is annealed at temperatures between 235 and 250°C. Samples with molecular weights from 2 000 to 26 000 are obtained. The melting behaviour of the copolyesters is determined by the crystallinity of the precondensate, the counit content, and the degree of polymerization.     

Liquid Crystalline Polythiophenes With Amphiphilic Side Chains

A series of poly(thiophene) derivatives with decyl‐oligo(oxyethylene) side groups, (PDnET) is synthesized via oxidative coupling polymerization. PD3ET and PD4ET with longer oligo(oxyethylene) units exhibited a liquid crystalline phase with well‐ordered lamella structures, although PD3ET showed a more ordered structure than PD4ET. PD1ET and PD2ET have shorter oligo(oxyethylene) groups than PD3ET and show less‐ordered structures with liquid‐crystalline phase observed. The UV‐vis spectra indicated that the maximum absorption wavelengths of PDnET increase when the number of oxyethylene units increases from 1 to 3; however, the maximum absorption wavelength of PD4ET is lower than that of PD3ET. Therefore, the most ordered and conjugated structures are obtained when the number of oxyethylene units is three.     

Preparation of regularly Sequenced polyamides,containing definite numbers of oxyethylene units

Polyamides 3 containing constant and definite numbers of oxyethylene units were prepared by condensation polymerization of suitable diamines and diesters, both of which containing oxyethylene units. The polymer structure was determined by IR and ¹H NMR spectroscopy. Almost all polymers are crystals melting at ≈ 40°C and show a complexation ability towards alkalimetal cations. It was also found that diesters containing oxyethylene units show a higher condensation rate than alkylene diesters, which is explained by an inductive effect of the ether oxygene. However, no remarkable difference in the condensation rate was found between diamines containing oxyethylene units and the corresponding aliphatic diamines.     

Cristallisation de poly(oxyéthylène)s segmentés

Two homologous series of segmented poly(oxyethylene)s, comprising from 1 to 4 blocks, were studied by differential scanning calorimetry, dilatometry and low-angle X-ray scattering. The polymers used were synthesized by condensation of α,ω-dihydroxy poly(oxyethylene)s with molecular weights of 2750 and 10600, respectively, upon 2,4-toluene diisocyanate. It was shown that the structure of these polymers is lamellar as for the usual poly(oxyethylene)s, but the degree of crystallinity and the melting temperature decrease appreciably with increasing degree of condensation. The thickness of the lamellae of the two-block polymers increases drastically and stepwise with crystallization temperature, exactly as in the case of weakly polydisperse, ordinary poly(oxyethylene)s. On the other hand, the thickness of the lamellae is little affected by the crystallization temperature for tri- and tetra-block polymers. The conclusion is drawn that this is due to a blocking of the urethane groups during the annealing process. As these groups are excluded from the crystalline domains, they play the same rǒle as end groups of the chains in ordinary poly(oxyethylene)s.     

Synthesis of poly(ethylene glycol)-modified urethane acrylates and their soap-free emulsification

In order to prepare the soap-free emulsion of urethane acrylates, poly(ethylene glycol)-modified urethane acrylates (PMUA), containing poly(oxyethylene) chains as terminal groups, were synthesized by reaction of poly(ethylene glycol) (PEG) with residual isocyanate groups. The size of the droplets of PMUA emulsions decreases as the molar ratio of PEG to 2-hydroxyethyl methacrylate (2-HEMA) increases. The interfacial activity of PMUA was confirmed by the measurement of the adsorption isotherm at the water/benzene interface. The chain length of poly(oxyethylene) and the type of polyol (PTMG, PPG) affects significantly the size of the droplets and the stability of the PMUA emulsions.     

Polymethacrylate-supported linear polyethers as solid-liquid phase transfer catalysts

Oligo(oxyethylene)s immobilized as pendant groups on a polymethacrylate-based resin were used as phase transfer catalysts in the reaction of solid alkali phenoxides with octyl halides in toluene and in the synthesis of benzyl acetate from benzyl bromide and solid alkali acetates in chloroform. The resins are cross-linked homopolymers or copolymers of methyl ethers of oligo(ethylene glycol) methacrylates of the general formula H₂C?C(CH₃)COO(CH₂CH₂O)_n CH₃ with n = 4 (MG4), 8 (MG8) or 22 (MG22), the comonomers being styrene, methyl methacrylate (MMA), acrylonitrile or 4-vinylpyridine. The conversion of the organic halides into the respective products were found to be all pseudo first order reactions and the observed rate constants are proportional to the amount of added catalyst and decrease with increasing crosslinking density of the catalyst. Catalysts with longer oligo(oxyethylene) chains have considerably higher activity. Incorporation of more than 50 mol-% MMA comonomer decreases the catalytic activity at least for the benzyl bromide reaction, but the structure of the comonomer has no significant effect. The catalysts are easily synthesized in large quantities from commercially available monomers.     

Darstellung und eigenschaften von copolyamiden mit oxyethylengruppen in definierter sequenz

The polyamides 3 – 5 were synthesized from α,ω-diamino-substituted oligo(oxyethylene)s ( 1 ) and bis-chlorides of dicarboxylic acids ( 2 ). As copolymers with defined sequences they contain up to five oxyethylene units per repeating unit. Hereby properties like solubility, thermal stability and complexing ability towards alkali metal cations are influenced.     

Viscometric characterization of poly(oxyethylene)-block-poly(oxypropylene)-block-poly(oxyethylene) in aqueous solution

Viscometric measurements were carried out to characterize poly(oxyethylene)-block-poly-(oxypropy1ene)-block-poly(oxyethy1ene) (POE-POP-POE) in aqueous solution. The results were discussed in terms of a core-shell model of intramolecular phase separation which is based on (i) the selectivity of the solvent water, and (ii) the incompatibility of the POE and POP blocks. The interaction between the two blocks was analysed by vapour pressure osmometry and vapour sorption investigations. The results are:

• 1 The two homopolymer blocks (POE and POP) forming the triblock copolymer are incompatible with each other as vapour pressure osmometry and vapour sorption measurements using ethylbenzene as solvent have shown. This incompatibility of the blocks as well as the selectivity of the solvent water with respect to the different blocks causes the intramolecular (and intermolecular) phase separation of the copolymers in aqueous solution.
• 2 The viscometric data of the aqueous block copolymer solutions can be discussed in terms of the generally accepted core-shell model. This model for the structure of the self-organized molecules includes POP gel core (“melt”) surrounded by solvated POE shell. A quantitative analysis according to this simplified view shows that the hydrodynamic volume of the copolymer molecules is determined by the POE blocks. In the temperature range ? > 30°C, the influence of the POP block on the molecular dimensions is negligible, whereas at ? < 30°C the contributions of the POP and POE to the molecular volume are comparable.
• 3 Kuhn's statistical segment length of POE in the triblock molecules comprises about 4–5 monomeric units. The theta temperature of the triblock copolymer molecules is nearly identical to that of pure POE ((369 ± 3)K).

     

13C NMR study of O-(2-hydroxypropyl)cellulose

The proton-decoupled signal of methyl carbons of O-(2-hydroxypropyl)cellulose (HPC) ( 1b , m ≥ 1) was found to be split into two peaks. The results of experiments on lanthanide shift and the dependence of the relative intensities of both peaks on the molecular weight of poly(oxypropylene) [poly(propylene oxide)] (PPO) indicated that the low-field peak results from the terminal hydroxypropyl groups and the high-field peak from the inside oxypropylene units. From the ratio between the intensities of the two peaks and the molar substitution (MS) (average number of oxypropylene units per anhydroglucose (AHG) unit), the degree of substitution (DS) (average number of hydroxyl groups substituted per AHG unit) was calculated. This new method could be applied to samples of low-MS to which the conventional method based on the ¹H NMR technique alone was inapplicable. From the analysis of ¹³C NMR spectra of HPC samples differing in MS, an authentic structural picuture of the HPC molecule could be proposed.     

Influence of the far order effect on the reactivity of functional end groups of macromolecules in non-equilibrium polycondensation

The influence of the number of oxyethylene repeating units in the oligomeric derivatives of ethylene bis(4-chlorocarbonylbenzoate) ( 1 , n = 3, 6,4, 13, 22,3, 45 and 68) on the reactivity of the chlorocarbonyl end groups in the acceptor-catalytic esterification was determined by means of thermodynamic and kinetic investigations in diluted solutions. The violation of the principle of equal reactivity was found to be caused by the far-order effect, when with increasing chain length the effective local concentration of oxyethylene repeating units increases in the environment of the end group whose reactivity is determined by the ratio between the “solvating ability” of the repeating units and the solvent. The far-order effect influences not only the kinetics, but also the reaction mechanism.