Structural studies of polyethers. IX. Planar zigzag modification of poly(ethylene oxide)

Takahashi, Yasuhiro; Sumita, I.; Tadokoro, Hiroyuki

doi:10.1002/pol.1973.180111103

Cited by 205 publications

(189 citation statements)

References 21 publications

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“…Such materials will be tested for the adsorption of heavy metals such as copper, mercury, cadmium and nickel Indeed, the strong affinity of PEOs for metal ions (Sakai et a11986, 1993;Takahashi et at 1973) could be utilized to design clay-based recyclable adsorbents.…”

Section: Discussionmentioning

confidence: 99%

Intercalation of Al₁₃-Polyethyleneoxide Complexes into Montmorillonite Clay

Montargès¹

1995

Clays and clay miner.

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Abstract--Novel promising modified days adsorbents were synthesized by intercalating hydroxy-Al polymer associated with poly(ethyleneoxide) in the interlayer of montmorillonite. Two different PEOs of low molecular weight (600) and high molecular weight (100,000) were used. In both cases, the resulting materials are hydrolyticaUy stable and display a slightly better crystallinity than the materials prepared in the absence of PEO. Thermal analysis and infrared spectroscopy indicate changes in the PEO molecular conformation after intercalation revealing interactions between the polycations and the organic molecules. The chain length of the polymer has a strong influence on the surface area of the pillared materials obtained after calcination at 500~ The use of the high molecular weight polymer leads to products with a higher specific surface area (about 400 m2/g) whereas the lower molecular weight compound does not modify significantly the surface areas. This behavior can be explained by the different nature of the species intercalated in the interlayer. PEO(600) leads to isolated organometallic species whereas PEO(100,000) seems to lead to a network of complexed polycations linked by ethylene oxide units. In the case of the PEO(100,000), high amounts of polymer in the pillaring solution provoke a partial dissolution of the octahedral layer of the clay.

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Section: Discussionmentioning

confidence: 99%

Intercalation of Al₁₃-Polyethyleneoxide Complexes into Montmorillonite Clay

Montargès¹

1995

Clays and clay miner.

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“…Para o caso da expansão interplanar de 9,0Å, uma conformação na forma helicoidal poderá ser possível 23,24 . Embora esta conformação seja a mais estável no polímero isolado, é bastante provável que no caso dos nanocompósitos, a orientação seja realmente linear, conformação observada para o polímero estirado 25 . Estudos a baixos ângulos de filmes orientados estão em progresso no sentido de dar informações a respeito da conformação linear ou helicoidal das cadeias de PEO.…”

Section: Figura 6 Medidas De Espectrometria No Infravermelho Do Nanounclassified

Síntese e caracterização dos nanocompósitos K0,1(PEO)xMoS2 (X= 0,5; 1,2)

Adad¹,

Grothe²

1998

Quím. Nova

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Recebido em 29/4/97; aceito em 29/6/98 SYNTHESIS AND CHARACTERISATION OF THE NANOCOMPOSITES K 0,1 (PEO) X MoS 2 (x= 0,5; 1,2). The reaction of an aqueous solution of poly(ethylene oxide) (PEO -mw 100.000) with a neutral aqueous suspension of single layers of MoS 2 was studied. The single layers aqueous suspension was prepared by first intercalating lithium (using n-Butyllithium in n-hexane) and reaction of these ternary compound with water under ultrasound stirring. The suspension was washed several times with water until neutral pH. The suspension was mixed with the PEO aqueous solution in the presence of KCl. Two single phase compounds were obtained with the expansion of 4,8 and 9,0Å, attributed to the solvation of the intercalated potassium cations with mono and double layers, respectively. Keywords: molybdenum disulphide; layered compounds; nanocomposites. ARTIGO INTRODUÇÃOUm tema bastante estudado desde a década de 70 é a quími-ca de intercalação em dicalcogenetos de metais de transição dos grupos IV a VIB, com estruturas lamelares 1 . A grande limitação desses sistemas é que a intercalação somente é possível quando o agente intercalante consiste de um cátion solvatado ou não, entre lamelas adjacentes. O interesse desses sistemas reascendeu drasticamente quando percebeu-se que essas matrizes poderiam ser esfoliadas (separação de lamelas individuais), produzindo uma suspensão de monolamelas em um solvente qualquer e que essas monolamelas poderiam ser posteriormente reagrupadas, após um processo de adsorsão de moléculas na sua superfície. A partir dessa descoberta, a técnica superou o limite da intercalação de cátions, passando ao encapsulamento de moléculas neutras 2 e até estruturas poliméricas [3][4][5][6][7] . Os materiais assim obtidos, consistem de uma mistura de dois compostos em nível molecular os quais passaram a ser chamados de nanocompósitos, em função das dimensões dos seus parâmetros de rede.Atualmente o trabalho tem se concentrado na obtenção de materiais que combinam as propriedades físicas, químicas e estruturais das matrizes inorgânicas com as propriedades do material orgânico encapsulado, procurando produzir materiais para aplicações industriais. Uma das dúvidas que persiste nesses nanocompósitos é a presença ou não do cátion molibdênio no estado de oxidação +3 nas monolamelas. A presença dessa espécie reduzida induziria a existência de cátions solvatados adsorvidos na superfície das mesmas, que poderiam ser trocados por outras espécies catiônicas. O procedimento passaria a ser encarado ainda como um processo de troca iônica ou solvatação dos cátions adsorvidos e não solvatação das lamelas puras propriamente ditas.O presente trabalho reporta a preparação de nanocompósi-tos através do encapsulamento de poli(óxido de etileno) (PEO) utilizando-se uma matriz lamelar do grupo VIB (2H-MoS 2 ). Baseando-se no fato de que o PEO é um bom condutor iônico e possui a característica de substituir a camada de hidratação dos cátions intercalados, aliado a boa condutividade eletrônica da matriz, esse sistem...

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“…Significantly different mechanisms have been proposed for these two polymers with different morphologies 11 -13 ; i.e., chain extended vs. chain folded. Several polymers, such as poly(ethylene glycol) 22 and syndiotactic polypropylene 23 have been shown to undergo similar conformational transformation on drawing. However, the unusual stress-strain curve has not been reported for these polymers probably due to differences in morphology.…”

Section: Edrxdrmentioning

confidence: 99%

Unusual Stress–Strain Behavior in Ultra-Drawn Films of High Molecular Weight Poly(4-methyl-1-pentene)

Kanamoto

Ohtsu

1988

Polym J

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KEY WORDSPoly(4-methyl-1-pentene) / Ultradrawing / Unusual StressStrain Behavior / Crystal Transformation / New Crystal Form / Recently, ultradrawing of flexible chain polymers has been extensively studied to achieve the maximum mechanical properties.1 -3 Among many polymers studied, only ultrahigh molecular weight (UHMW) polyethylene4-7 and polypropylene 8 -10 have been ultradrawn to the limits in terms of mechanical and physical properties approaching limits.In our current study of ultradrawing of poly(4-methyl-l-pentene) (P4MlP), it was found that single crystal mats of UHMW-P4M 1P could also be drawn to a high draw ratio (DR) of 80 by a two-stage drawing technique. 5 · 8 The ultradrawn films exhibited unusual stress-strain curves for ambient tensile testing. The curve was characterized by three distinct regions consisting of an initial elastic region, a yield region, and finally, a post-yield region. A similar stress-strain curve has been reported only in a few polymers such as wool 11 • 12 and oriented polypivalolactone 13 and poly(butylene terephthalate) 14 where the alpha-beta (helix-planar zigzag or gauchetrans) transformation occurred ·on extension. In contrast to these polymers, however, ultradrawn UHMW-P4MlP showed tensile moduli of 7.5-9.1 GPa in the post-yield region, which were significantly higher than the crystal modulus of 2.9-6.7 GPa 15 ' 16 reported for the ordinary tetragonal form of P4MlP. 17 · 18 In this communication, we report unusual stress-strain behavior observed in ultradrawn films of UHMW-P4MIP and studied in relation to the specific morphology and the crystal structural or conformational changes that occurred during extension at room temperature. EXPERIMENT ALThe UHMW-P4MlP used was a highly isotactic polymer with viscosity average MW of 1.5 x 10 6 • Solution-grown crystals (SGC) were isothermally precipitated from a 0.2 wt% solution in xylene kept at 50°C over 20 h. SGC mats were obtained by slowly filtering the crystal suspension followed by drying at 50°C.A two-stage drawing technique 5 · 8 was utilized for uniaxial drawing of SGC mats of UHMW-P4MlP. For the first-stage drawing, a solid-state coextrusion technique developed by Porter et al. 19 was used. For the secondstage, a conventional tensile drawing technique was used. Extrudates having an extrusion DR (EDR) of 6 prepared at 180cc were drawn at 180-200°C in an air oven equipped with a Tensilon tensile tester HTM-100. The total DR was defined by DR 1 = EDRxDR.179

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Structural studies of polyethers. IX. Planar zigzag modification of poly(ethylene oxide)

Cited by 205 publications

References 21 publications

Intercalation of Al₁₃-Polyethyleneoxide Complexes into Montmorillonite Clay

Intercalation of Al₁₃-Polyethyleneoxide Complexes into Montmorillonite Clay

Síntese e caracterização dos nanocompósitos K0,1(PEO)xMoS2 (X= 0,5; 1,2)

Unusual Stress–Strain Behavior in Ultra-Drawn Films of High Molecular Weight Poly(4-methyl-1-pentene)

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Structural studies of polyethers. IX. Planar zigzag modification of poly(ethylene oxide)

Cited by 205 publications

References 21 publications

Intercalation of Al13-Polyethyleneoxide Complexes into Montmorillonite Clay

Intercalation of Al13-Polyethyleneoxide Complexes into Montmorillonite Clay

Síntese e caracterização dos nanocompósitos K0,1(PEO)xMoS2 (X= 0,5; 1,2)

Unusual Stress–Strain Behavior in Ultra-Drawn Films of High Molecular Weight Poly(4-methyl-1-pentene)

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Intercalation of Al₁₃-Polyethyleneoxide Complexes into Montmorillonite Clay

Intercalation of Al₁₃-Polyethyleneoxide Complexes into Montmorillonite Clay