PMMA-block-polyisobutylene-block-PMMA prepared with α,ω-dilithiated polyisobutylene and its characterization

Summary A triblock copolymer of PMMA and polyisobutylene(PIB), PMMA-block-PIB-block-PMMA, was prepared by anionic polymerization of methyl methacrylate initiated with , -dilithiated poly(isobutylene) diisobutylate in tetrahydrofuran at -60°C. The molecular weight distribution of the block copolymer was close to that of the starting PIB. The stereoregularity of PMMA block was predominantly syndiotactic. Proton spin-lattice relaxation time and solution viscosity of the block copolymer in acetone, which is non-solvent for PIB, indicate that the block copolymer forms rigid spherical particles. Stereocomplex formation with isotactic PMMA was also studied.     

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).     

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.     

Synthesis and characterization of nylon-polyisobutylenenylon triblock copolymers

Nylon-6-polyisobutylene-nylon-6 triblock copolymers have been synthesized by converting telechelic polyisobutylene diols to , -diisocyanate polyisobutylenes and using these macroactivators, in conjunction with strong base, to induce the subsequent anionic polymerization of -caprolactam. Pure block copolymer was obtained by suitable sequential extraction. Products were characterized by composition, molecular weight and DSC.     

Effects of crystallinity and supermolecular formations on the interfacial shear strength and adhesion in GF/PP composites

Aim of this study was to screen the morphological effects on the interfacial shear strength (i) in glass fibre (GF) reinforced isotactic polypropylene (iPP) model composites. i was determined by a modified single fibre pull-out technique. It was established that the relation between i (5–6 MPa) and the yield stress of the iPP (y30 MPa) is at about 1:6 and that the i values were not influenced by the mophological superstructure set under isothermal crystallization conditions. Increased i was only observed when specimens were produced non-isothermally, by quenching (i9 MPa). This improvement could not be related to thermal shrinkage stresses. The enhancement in i was attributed to better wetting and improved adhesion due to the enlarged amorphous PP (aPP)-phase. A schematic adhesion model considering the wetting behaviour of aPP and iPP was proposed.     

Synthesis of novel telechelic monodispersed nonconjugated dienes

Summary The synthesis of novel telechelic monodispersed nonconjugated dienes from commercially available , -dithiols and dienes is presented. The batch reaction produced a polydispersed. mixture separable with difficulty whereas a dropwise addition of dithiol onto an excess of , -diene in the presence of peroxide led selectively and quantitatively to the addition product: diene-dithiol-diene.     

Silphinene Sesquiterpenes as Model Insect Antifeedants

Silphinene sesquiterpenes are established chrysomelid antifeedants. In this work, nine silphinene analogs, 11-acetoxy-5-angeloyloxysilphinen-3-one (1), 11-acetoxy-5-tigloyloxysilphinen-3-one (2), 11-acetoxy-5-iso- butyryloxysilphinen-3-one (3), 11-hydroxy-5-angeloyloxysilphinen-3-one (4), 11,5-dihydroxysilphinen-3-one (5), 11,5-diacetoxysilphinen-3-one (6), 5,11-diisobutyryloxysilphinen-3-one (7), silphinen-3,5,11-trione (8), and O-methyl-5-epicantabrenolic acid methyl ester (10), and a presilphiperfolane sesquiterpene (9) were tested against several divergent insect species, including the lepidopteran Spodoptera littoralis, the chrysomelid Leptinotarsa decemlineata, and five aphid species, and their antifeedant effects were compared with those of picrotoxinin, a GABA-antagonist, and thymol, an allosteric modulator for insect GABA receptors. All insects tested responded to at least one silphinene analog and/or GABA antagonist. Compound 3 and thymol were effective antifeedants against all species tested except S. littoralis, with varying potencies according to their feeding ecologies. The toxicity of these compounds was species-dependent and did not correlate with their antifeedant effect.     

Intermediate angle scattering functions and local chain configurations of semicrystalline and amorphous polymers

Summary Molecular scattering functions at intermediate scattering vectors, of =(4/ sin/2) in the range 0.03 to 1.0Å^–1, are found to be extremely sensitive to the local configurations of polymer chains in both semicrystalline and amorphous states. Available experimental results of intermediate angle neutron scattering (IANS) from melt-crystallized polyethylene and isotactic polypropylene provide compelling evidence that adjacent re-entry is rare. The rotational isomeric state model satisfactorily accounts for IANS and chain dimensions of polycarbonate in the amorphous state.     

Enzymatic grafting modification of polyethylene film in nonaqueous solvents

Summary Diblock and triblock copolymer of -caprolactone(-CL) and styrene(St) were obtained by the combination of two different polymerization process, namely enzymatic ring-opening polymerization(ROP) and atom transfer radical polymerization(ATRP) methods. Mono-/di- hydroxyl terminated macromolecules were prepared by enzymatic ROP of -CL in the presence of Novozyme-435 and methanol/ethylene glycol as biocatalyst and initiator, respectively, and subsequently converted to bromine ended polycaprolactone(PCL) by the esterification of the resulting macromolecules with -bromopropionyl bromide. The mono- and difunctional macroinitiators were employed in ATRP of styrene using CuCl/2, 2-bipyridine(bpy) as the catalyst system. The GPC and ¹H-NMR analysis indicated a controlled/living radical polymerization which resulted in the formation of block copolymers with narrow polydispersities.     

Comparison of some 4- and 4,4′-substituted derivatives of stilbene for their reactivities towards the benzoyloxy radical

Summary 4-Fluoro- and 4,4-difluorostilbene are similar in their reactivities towards the benzoyloxy radical; a similar conclusion has been reached in respect of 4-chloro- with 4,4-dichlorostilbene and 4-phenyl-with 4,4-diphenylstilbene. These results have been obtained by consideration of the numbers of benzoate and phenyl end-groups in poly (methyl methacrylate) made using benzoyl peroxide in the presence of the appropriate derivative of stilbene.     

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     

Dewatering deposits formed in purifying effluent from refractory factories by vacuum filtration

Conclusions The residue formed from effluent contaminated with chamotte dust, with coagulation and without coagulation, is thoroughly dewatered on vacuum equipment with concentrations of more than 700 kg/m³ of suspended particles in the residue.Residues obtained from effluent contaminated with mixtures of chamotte and clay dust in the ratio 41, 11, and 14 are dewatered less effectively than chamotte residues. The residue from a mixture of chamotte and clay 41 is dewatered with a minimum concentration of 809 kg/m³; the residue from the mixture of chamotte and clay 11 can be satisfactorily dewatered only with a high vacuum (640 mm Hg) and with a filter cycle time longer than that used in existing equipment. With a filter cycle of 30 min the thickness of the skin of uncoagulated residue was 13 mm. The coagulated residue from a mixture of clay and chamotte 11 even after 14 days holding had too low a concentration, and in practice cannot be dewatered on a vacuum filter. The residue from mixtures of 14 chamotte and clay is dewatered very ineffectively. The thickness of the cake with a filter cycle time of 20 min for uncoagulated residue was only 4 mm.Translated from Ogneupory, No. 6, pp. 17–20, June, 1970.     

Synthesis and characterization of amphiphilic polyisobutylene/poly(ethylene glycol) di- and triblock copolymers

Summary Di- and triblock copolymers of polyisobutylene PIB and poly(ethylene glycol) PEG have been prepared and characterized. The syntheses involved the capping with tolylene 2,4-diisocyanate TDI various molecular weight -phenyl--(p-phenol) polyisobutylenes C₆H₅-PIB-C₆H₄OH and ,-di-(p-phenol)polyisobutylenes HOC₆H₄-PIB-C₆H₄OH, or commercially available mono- and di-hydroxyl-terminated PEGs. In this manner a series of PIB-b-PEG diblock copolymers, and PEG-b-PIB-b-PEG and PIB-b-PEG-b-PIB triblock copolymers have been obtained. The complete removal of the prepolymers from these amphiphilic sequential copolymers by conventional solvent extraction techniques could not be achieved because of the very high emulsifying action of the latters. In contrast, satisfactory separation was obtained by column chromatography using mixed (polar/nonpolar) eluents. The blocking efficiencies and composition of the block copolymers have been determined.Part XL V of the Series on New Telechelic Polymers and Sequential Copolymers by Polyfunctional Initiator-Transfer Agents (Inifers).     

Synthesis of monocarboxylic polyoxyethylenes

Summary The various methods of synthesis which can be used to prepare -carboxy polyoxyethylenes are reviewed. The synthesis and the purification of -methoxy -carboxy polyoxyethylenes ( ) are reported. The process consists of the reaction of halogenoacetic acids with an -methoxy -sodium hydroxylate polyoxyethylene followed by a purification by extraction. ,-dimethoxy and -methoxy -ethyl carboxylate polyoxyethylenes were synthesized.     

Cryochemical Synthesis of Mn-Containing Poly(p-Xylylene)

A Mn-containing polymer was produced by solid-state photopolymerization of a cocondensated mixture of p-xylylene with Mn at 80 K. It was shown that during simultaneous deposition p-xylylene and Mn formed both - and -complexes. Irradiation of the system by UV light resulted in polymerization of p-xylylene with the destruction of the unstable -complexes, while the -bonded compounds were incorporated into the polymer chains. Complexes of Mn with benzyl-type radicals of the polymerized system were also observed. Prolonged storage of the polymerized material at ambient temperature under vacuum led to the gradual decomposition of the organomanganese compounds and complexes.     

Cooperative inclusion of sodium 1-pyrenesulfonate by γ-cyclodextrin

Summary The interaction of -cyclodextrin(-CD) with sodium 1-pyrenesulfonate(PS) was studied spectrophotometrically. -CD was found to cause much larger decrease in the absorption maxima of PS than -CD. The fluorescence spectra of PS in the presence of -CD showed excimer emission, while those of PS with -CD showed only monomer emission, indicating that -CD forms 12 (-CDPS) complexes in which two PS molecules are included in the -CD cavity in a face-to-face fashion. The binding isotherm showed a sigmoidal curve. The association constants were estimated by computer simulation of the binding curve. The 12 (CDPS) complex was found to be much more stable (K=10⁶ M^–1) than the 11 complex (K=1 M^–1). At high concentration of -CD another -CD cooperates in binding two PS molecules, resulting in the formation of a 22 complex.     

Fertilizer requirements for specified yield targets. I. Theoretical derivation of mathematical models for the computation of soil and fertilizer nutrient efficiencies

The conventional deduction procedure of computation of soil () and fertilizer () nutrient efficiencies for the amount of fertilizer required for specified yield targets does not make provision of the amount of soil nutrient derived by crops from the available pool of soil nutrients not accounted for in the amount extracted by a soil test procedure. The derivation of two mathematical models, viz., Tamil Nadu Agricultural University Model I [TNAU Model I] and Model II [TNAU Model II] is reported in this paper which aim at computing the soil () and fertilizer () nutrient efficiencies not accounted for by the conventional method.In the case of TNAU Model I, the relationship between the nutrient uptake (U) and the soil (S) and the fertilizer (F) nutrients was established by assuming a functional relationship of the type U =S +F such that 0 1 and 0 1. In TNAU Model II the same relationship was established as U =S +F + such that 0 1, 0 1 and > 0. The term in the latter model is a measure of the amount of soil nutrient the crop absorbs from a slowly available pool of nutrients not accounted for in the amounts extracted by the soil test procedure employed or applied through fertilizer.The field verification of these models is reported elsewhere.     

Enthalpy relaxation studies in isotactic polystyrene. Effects of crystallinity

Summary The enthalpy relaxation of the amorphus isotactic polystyrene is strongly affected from the crystalline phase induced by annealing at temperatures between Tg and Tm. All the parameters describing the relaxation process, H, T_max and T_ons depend also on the above T_g annealing conditions as the induced crystallinity alters the quantity and the quality (i.e.Tg, T_gons, T_g) of the remaining amorphous phase.     

Cationic modifications of polychloroprene

Summary The synthesis of the novel graft-block copolymer poly[chloroprene-g-(isobutylene-b--methylstyrene)], i.e., a polychloroprene backbone carrying isobutylene/-methylstyrene block copolymer branches, is described. The synthesis was accomplished by exploiting detailed insight into the mechanisms of initiation of isobutylene and -methylstyrene polymerization, and termination of isobutylene polymerization.     

Synthesis and polymerization of 2-(β-N-ethylenediphenylamine)-2-oxazoline

Summary The synthesis of 2-(-N-ethylenediphenylamine)-2-oxazoline and its living cationic polymerization in the presence of methyltosylate are described. This 2-substituted 2-oxazoline was used for the synthesis of a ABA triblock copolymer with poly(N--(N-diphenylamine)propionylethylenimine) as A block and poly(ethyleneglycoladipate) as B block.