Synthesis and characterization of amphipathic poly(methyl methacrylate)-b-poly(ethylene oxide) diblock copolymers

Summary This paper describes the synthesis and characterization of amphipathic diblock copolymers of poly(methyl methacrylate) (PMMA) and poly(ethylene oxide) (PEO). The synthesis involved the coupling of acyl chloride-terminated PMMA block with methoxy poly(ethylene oxide) (MPEO). Carboxylic acid chloride-terminated PMMA was generated by treating with thionyl chloride the parent carboxylic PMMA, which was prepared by free radical polymerization of methyl methacrylate (MMA) using benzoyl peroxide (BPO) as the initiator and -mercaptopropionic acid (MPA) as the chain transfer agent. The proposed mechanism of MMA polymerization is in good agreement with the experimental results which indicate that as a side reaction nonfunctional (aromatic) counterpart is produced in a small quantity. The coupling of the acyl chloride-terminated PMMA with MPEO was quantitative.     

Mark-Houwink-Sakurada coefficients for conventional poly(methyl methacrylate) in tetrahydrofuran

Summary Intrinsic viscosities [] in tetrahydrofuran (THF) at 30°C are reported for ten narrow molecular weight distribution poly(methyl methacrylate) (PMMA) samples covering nearly two orders of magnitude in molecular weight. By combining the viscosity results with absolute weight-average molecular weights determined via low-angle laser light scattering (LALLS) experiments, we have accurately determined the Mark-Houwink-Sakurada (MHS) parameters for this polymer-solvent pair (K=7.56x10⁵ and a=0.731, when [] is in dL g^-1).     

Characterization of some organic poly(aminiumphosphate)s

Summary Metachromatic reactions of MB and AO are studied with poly(aminium phosphate)s. The main band() at 665 m and 492 m for MB and AO are shifted to 580 m and 455 m respectively (-bands). The metachromatic values at different concentrations of poly(aminium phosphate)s are also reported. The dye association for MB with these polymer derivatives is investigated conductometrically as well. It is observed that MB can be at the most bind with the phosphate residue of polymer upto 11 molar ratio. The polymeric nature was further established by paper chromatographic technique in Terry's, Ebel's & Pfrengle's solvents.     

Synthesis of new metal-containing side-chain monomers and polymers

New metal-containing vinyl monomers, hexyl-6-oxy-{4-[4-(4-carboxy cyclopentadienyl manganese tricarbonyl phenyl)phenyl]benzoyloxy}methacrylate and hexyl-6-oxy-{4-[4-(4-ferrocenoyl phenyl)phenyl]benzoyloxy}methacrylate, and the corresponding homopolymers and random copolymers with hydroxy monomer hexyl-6-oxy-{4-[4-(4-hydroxyphenyl)phenyl]benzoyloxy}methacrylate were synthesized. The compounds were characterized by¹H NMR; their thermal behavior was investigated by means of differential scanning calorimetry. Monomers and polymers containing the ferrocene unit melt at lower temperatures than those derived from the cyclopentadienyl managanese tricarbonyl moiety. The melting temperatures of the monomers and polymers ranged from 399 to about 515 K, Both monomers and polymers failed to exhibit mesogenic behavior. Values ofM _n,M _w,M _w/M _n, and degree of polymerization were obtained by gel permeation chromatography. TheM _n ranged from 16,500 for the copolymer containing hexyl-6-oxy-{4-[4-(4-ferrocenoyl phenyl)phenyl] benzoyloxy}methacrylate and hydroxy monomer hexyl-6-oxy-{4-[4-(4-hydroxyphenyl)phenyl]benzoyloxy}methacrylate at a 1:3 ratio to 26,000 for the copolymer containing hexyl-6-oxy-{4-[4-(4-carboxy cyclopentadienyl manganese tricarbonyl phenyl)phenyl]benzoyloxy}methacrylate and hydroxy monomer hexyl-6-oxy-{4-[4-(4-hydroxyphenyl)phenyl]benzoyloxy}methacrylate at a 1:3 ratio.M _w/M _n ranged from 1.6 in the case of the copolymer containing hexyl-6-oxy-{4-[4-(4-carboxy cyclopentadienyl manganese tricarbonyl phenyl)phenyl]benzoyloxy}methacrylate and hydroxy monomer hexyl-6-oxy-{4-[4-(4-hydroxyphenyl)phenyl]benzoyloxy}methacrylate at a 1:3 ratio to 2.2 in the case of poly(hexyl-6-oxy{4-[4-(4-carboxy cyclopentadienyl manganese tricarbonyl phenyl)phenyl]benzoyloxy}methacrylate).     

Synthesis,electrical and optical properties of multifunctional poly[2-(2-ethyl-hexyloxy)-1,4-phenylenevinylene]

Summary Branched monoalkoxy-substituted poly[2-(2-ethylhexyloxy)-1,4-phenylenevinylene] (EH-PPV) was prepared in thin films via the water-soluble precursor technique and solution elimination method. These precursor polymer films could be stretched up to 8 times, and the drawn films of the EH-PPV could be doped with I₂ and FeCl₃ to give conductivities of 5.28x10^-3 and 0.56 S/cm, respectively. The third-order nonlinear optical susceptibility of the polymer was determined by using third harmonic generation (THG) method at 1907 nm, fundamental wavelength. Measured ⁽³⁾(–3; ,,) value was 3.8x10^-12 esu. The maximum emission wavelength of EH-PPV film in photoluminescence spectrum was 560 nm, corresponding to the yellowish red color.     

Intramolecular charge transfer complexes

Summary Radical copolymerization of N-ethyl-3-hydroxymethyl cartbazolyl methacrylate (EHMCM) with methacryloyl--hydroxyethyl-3,5-dinitrobenzoate (DNBM) and acryloyl--hydroxyethyl-3,5-dinitrobenzoate (DNBA), respectively, lead to intramolecular charge transfer complexes (CTC). In the case of EHMCM-DNBA copolymerization, a mechanism involving intermonomeric CTC participation is evidenced.Dedicated to Professor B. Vollmert's 60th anniversary     

Monotropic liquid crystalline poly(β-thioester)s containing bis (p-oxybenzoate) mesogenic units

Summary A new series of thermotropic liquid crystalline poly(-thioester)s was prepared by a Michael-type polyaddition of ,-polymethylenedithiols of different length to a mesogenic diacrylate containing two bis(p-oxybenzoate) units symmetrically connected through a dodecamethylene segment. The thermotropic behaviour was studied by combined DSC and thermal-optical analyses. All the poly(-thioester)s investigated exhibited quite unusual monotropic mesomorphism.     

Synthesis,electroconductivity and third-order nonlinear optical property of poly(2-isopropoxy-5-methoxy-1,4-phenylenevinylene)

Summary Asymmetrically disubstituted poly(2-isopropoxy-5-methoxy-1,4-phenylene-vinylene), PIMPV, was prepared in thin films via organic-soluble precursor polymer method. These polymer films could be easily stretched up to 7 times, and the drawn films of the PIMPV could be doped with FeCl₃ and I₂ to give conductivities of 26.9 and 11.3 Scm^-1, respectively. The third-order nonlinear optical susceptibility of the polymer was determined using third harmonic generation(THG) method at 1907 nm, fundamental wavelength. Measured ⁽³⁰⁾ (-3: , , ) value was 3.7x10^-12 esu.     

13C NMR spin-lattice relaxation in solid poly(methyl methacrylate)

Summary ¹³C spin-lattice relaxation rates R₁ in samples of solid PMMA have been measured with CP MAS NMR. Isotactic, atactic, syndiotactic, and the 12 i-s PMMA complex were measured, along with atactic samples containing bisdioxan or the monomer as a plasticizer. The reorientation of the -methyl protons is the dominant relaxation source for the methylene, -methyl and quarternary carbon nuclei. Increased mobility of the polymer in the presence of a plasticizer is not reflected in significant changes in R₁.Presented at the 22nd Microsymposium, Characterization of Structure and Dynamics of Macromolecular Systems by NMR Methods, Prague, July 20–23, 1981     

Properties ofSrMO 3-δ(M=Fe,Co) as oxygen electrodes in alkaline solution

Strontium ferrates and cobaltates with compositions SrFeO_3- (0.060.40) and SrCoO_3- (0.040.30) were synthesized. The dependence of the oxygen electrode properties on the value was examined in 1 mol dm^–3 KOH solution. In the SrFeO_3- series, the samples with 0.24<<0.29, showed the highest activity in both oxygen evolution and reduction reactions. In contrast, no strong dependence on the value was observed in SrCoO_3-, which also showed a high catalytic activity for oxygen evolution.     

Suppression of the α → β-nickel hydroxide transformation in concentrated alkali: Role of dissolved cations

The presence of dissolved cations such as Al and Zn in alkaline electrolyte (6 M KOH) suppresses the -nickel hydroxide transformation. The uptake of Al (10 mol%) and Zn (30 mol%) exhibited by the active material likely stabilizes the -phase. Dissolved Al is deleterious to the performance of the nickel hydroxide electrode, whereas, dissolved Zn enhances the specific discharge capacity of nickel hydroxide by approximately 25% showing that the mode of metal uptake is different in the two cases.     

High resolution transmission electron microscopic (HRTEM) determination of the preferentially exposed faces onγ-Al2O3 andη-Al2O3

High resolution transmission electron microscopy has been used to examine the crystallites in -Al₂O₃ and -Al₂O₃. -Al₂O₃ has been found to be nearly hexagonally shaped crystallites whose identity distances and angles of fringe patterns indicate that (110) planes are preferentially exposed. -Al₂O₃ showed preferentially exposed surfaces of (100), (110) and super imposed (111)/(211). This information is valuable to the catalyst researcher trying to model the surfaces of these two supports.     

Synthesis and characterization of three-branched star-like poly(γ-benzyl-l-glutamate)

Summary Three branched star-like poly(-benzyl-l-glutamate) was synthesized using three functional amine as an initiator, and characterized through light-scattering, ORD and intrinsic viscosity measurements. Experimental results suggest that the synthesized star-like poly(-benzyl-l-glutamate)s are composed of three branches of equal length.     

Effect of branched alkyl groups on physical properties in poly(ethylene-co-branched alkyl methacrylate)s

Summary Poly(ethylene-co-5.4 mol% n-alkyl/branched alkyl methacrylate)s (PEM) were prepared by a dehydrogenchloride reaction of poly(ethylene-co-5.4 mol% alkyl methacrylic chloride) with the corresponding alkyl alcohol to investigate effect of branching structure and length of alkyl ester on a few physical properties of PEM [glass transition temperature (T_g), degree of crystallinity in polyethylene region (X_c) and dielectric molecular motion], where the alkyl groups used here are n-propyl, n-butyl, n-hexyl, n-decyl, 2-ethylhexyl, 3,5,5-trimethylhexyl and 2-(1,3,3-trimethylbutyl)-5,7,7-trimethyloctyl. In the n-alkyl methacrylate copolymers, T_g and X_c were almost unchanged with the presence of alkyl ester, but T_g increased and X_c decreased in the highly branched alkyl methacrylate copolymers even at the low methacrylate content of 5.4 mol%.     

Determination of the microstructure of poly(methyl α-fluoroacrylate) by NMR spectroscopy

Summary The 300 MHz pmr, 282 MHz fmr and 20 MHz cmr spectra of poly (methyl -fluoroacrylate) that was prepared by free radical initiated polymerization have been recorded. They indicate the polymer to have a Bernoullian distribution of stereosequences, with = P(m) = 0.41. Pentad stereosequence distributions were measurable from the 282 MHz fmr spectra of this polymer, but only dyad and triad distributions could be determined from the pmr and cmr spectra, respectively.     

Elasticity of swollen polyvinyl alcohol and poly(vinyl acetate) networks

Summary In this paper we report on a series of unidirectional compression measurements carried out on chemically crosslinked polyvinyl alcohol (PVA) and poly(vinyl acetate) (FVAc) networks. The influence of the molecular mass and the molecular mass distribution of the primary chains on the mechanical properties has been studied. The PVAc gels were prepared by total acetylation of the PVA gels without producing changes in the network topology (topo-analogous transformation) (NAGY et al. 1978). The comparison between the mechanical behaviour of PVA and PVAc gels enables us to make a more detailed analysis of the molecular parameters relevant to the network structure.Presented at the 7th IUPAC Discussion Conference Polymer Networks, Karlovy Vary, CSSR, September 15–19, 1980     

Synthesis, Characterization and Optimum Reaction Conditions of Oligo-N, N′-bis (2-hydroxy-1-naphthalidene) Thiosemicarbazone

The oxidative polycondenzation reaction conditions of N, N-bis (2-hydroxy-1-naphthalidene) thiosemicarbazone (HNTSC) using air oxygen, H₂O₂ and NaOCl were studied in an aqueous alkaline medium between 50–90°C. Oligo-N, N-bis (2-hydroxy-1-naphthalidene) thiosemicarbazone was characterized by ¹H-NMR, FT-IR, UV-Vis, size exclusion chromatography (SEC) and elemental analysis techniques. Solubility testing of oligomer was investigated using organic solvents such as DMF, THF, DMSO, methanol, ethanol, CHCl₃, CCl₄, toluene acetonitrile, ethyl acetate, concentrated H₂SO₄ and an aqueous alkaline solution. Using NaOCl, H₂O₂ and air O₂ oxidants, conversion to oligo-N, N-bis (2-hydroxy-1-naphthalidene) thiosemicarbazone (OHNTSC) of N, N-bis (2-hydroxy-1-naphthalidene) thiosemicarbazone was found to be 85, 80 and 76%, respectively, in an aqueous alkaline medium. According to the SEC analyses, the number-average molecular weight, weight-average molecular weight and polydispersity index values of OHNTSC synthesized were found to be 1050 gmol^–1 1715 gmol^–1 and 1.63, using NaOCl, and 2137, 2957 gmol^–1 and 1.38, using air O₂ and 2155 gmol^–1 4164 gmol^–1 and 1.93, using air H₂O₂, respectively. Also, TG analysis was shown to be unstable of oligo-N, N-bis (2-hydroxy-1-naphthalidene) thiosemicarbazone against thermo-oxidative decomposition. The weight loss of OHNTSC was found to be 97.29% at 900°C.     

Effect of crystallinity on the dynamic mechanical relaxations of poly(butylene isophthalate)

Summary The viscoelastic spectrum of poly(butylene isophthalate) annealed at 90 °C for different times has been examined by dynamic mechanical spectroscopy.Crystallinity affects both the main a absorption associated with the glass to rubber transition and the sub-ambient secondary relaxation region. The latter results from two overlapping processes, ₁ and ₂, that have been evidentiated by a resolution procedure. Values of 52 and 76 kJ/mol have been obtained for the activation energies of the low (₁) and high (₂) temperature component respectively. It is suggested that these values are not affected by the methylene chain length and by the isomerism of the phthaloyl residue.     

Temperature dependence of the intensity of fluorescence of poly(n-vinylcarbazole) films

Summary The fluorescence spectra of thin films of poly(N-vinylcarbazole), PVCA, were measured at temperatures between 103 K and 535 K by constant excitation light intensity. Below 300 K, the corrected spectra were divided into bands belonging to different emitting species of PVCA. Temperature changes of the intensity of fluorescence of the two main excitation energy traps in PVCA are discussed using the simplified kinetic model of Johnson. Local anomalies on the curves of intensity of excimer fluorescence versus temperature measured at constant wavelength reflex the - and - relaxation regions in PVCA.     

Miscibility of poly(α-methyl styrene-co-methacrylic acid) with alkyl methacrylate-co-4-vinylpyridine copolymers

Summary The miscibility of blends of poly(-methyl styrene-co-methacrylic acid) (PMSMA) with various alkyl methacrylate polymers or poly(alkyl methacrylate-co-4-vinylpyridine) was studied by differential scanning calorimetry and Fourier transform infra red spectroscopy. PMSMA is immiscible with poly(methyl methacrylate), poly(ethyl methacrylate) and poly(n-butyl methacrylate). The introduction of 4-vinylpyridine by random free radical copolymerization within these alkyl methacrylate polymer chains enhanced the miscibility of these copolymers with PMSMA as a result of specific interactions that occurred between the carboxylic and pyridine groups, evidenced from the significant changes observed by FTIR in the carboxyl and pyridine ring regions. The density of interacting groups required for miscible blends depends on the size of the pendant group.