Liquid crystalline polysurfactant

Wang, S. E.; Li, Y.; Zhang, H. F.; Mo, Zhishen

doi:10.1007/bf00963134

Cited by 2 publications

(1 citation statement)

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“…The presence of polar groups in the main chain anisotropic distribution of nonpolar groups in the side chains is responsible for giving the liquid crystalline behavior to LCPs. 1,2 These polymers offer a number of potential applications in the field of science and technology due to excellent properties such as low coefficient of thermal expansion, good dimensional stability, high heat resistance, low melt viscosity, and chemical resistance. [3][4][5][6][7][8][9][10][11][12] However, LCPs show more complex behavior than flexible polymers.…”

Section: Introductionmentioning

confidence: 99%

Dielectric Spectroscopy of Pristine and O⁷⁺ Ion Irradiated NCO‐Terminated Polybutadiene‐Based Liquid Crystalline Polyurethane

Lal

Quamara

2014

Adv Polym Technol

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The dielectric constant (ε ) and loss factor (ε ) have been measured in NCO-terminated polybutadiene-based pristine and 100 MeV O 7+ ion irradiated liquid crystalline polyurethane in the temperature region of 80-300 K at frequencies ranging from 1 KHz to 1 MHz. The variation in ε with temperature in different temperature regions has been analyzed in relation to the dipole structure of the molecules. The ε -T plots of pristine liquid crystalline polyurethane (LCPU) reveal the presence of multiple relaxation processes associated with the crankshaft motion of but-2-ene groups, dipolar nature of carbonyl groups, and glass transition temperature, respectively. An additional dielectric loss peak is observed in irradiated LCPU samples associated with the Maxwell-Wagner-Sillars (MWS) polarization. There is an overall increase in ε in irradiated samples due to the dominance of MWS polarization arising from the large number of radiation-induced defect sites and free radicals. The loss in γ relaxation due to chain scissions of but-2-ene groups and the formation of new subpolar groups providing a new dipolar relaxation process is observed in irradiated LCPU samples. The variation in ε with fluence shows the occurrence of a secondary radiation induced crystallization in irradiated LCPU samples. The X-ray diffraction analysis also shows the effect of fluence on the crystalline nature of LCPU samples. C

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Section: Introductionmentioning

confidence: 99%

Dielectric Spectroscopy of Pristine and O⁷⁺ Ion Irradiated NCO‐Terminated Polybutadiene‐Based Liquid Crystalline Polyurethane

Lal

Quamara

2014

Adv Polym Technol

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Poli(Álcool Vinílico) Modificado com Cadeias Hidrocarbônicas: Avaliação do Balanço Hidrófilo/Lipófilo

Aranha¹,

Lucas

2001

Polímeros

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Resumo: Terpolímeros de poli(álcool vinílico) foram sintetizados por meio de reação de esterificação do PVA parcialmente hidrolisado com cloretos de ácidos graxos de comprimento de cadeia diferentes. O objetivo da síntese foi obter polímeros à base de PVA com pequenas variações no balanço hidrófilo/lipófilo e nas propriedades interfaciais de suas soluções. A modificação foi acompanhada por ressonância magnética nuclear de hidrogênio e as propriedades foram avaliadas pela variação na solubilidade e na tensão superficial. Foram obtidos polímeros modificados com baixos teores de grupamento hidrófobo. Testes de tensão superficial, realizados com os produtos solúveis em água, não mostraram variação dessa propriedade. A solubilidade dos produtos diminuiu sensivelmente mesmo para pequenas incorporações de grupamento hidrófobo. Foi observado que, para uma mesma massa, segmentos hidrófobos menores, distribuídos ao longo da cadeia, promovem maior modificação na solubilidade. Palavras-chave: Poli(álcool vinílico), ácidos graxos, esterificação, solubilidade. Chemical Modification of Poly(Vinyl Alcohol): Evaluation of Hydrophilic/Lipophilic BalanceAbstract: Poly(vinyl alcohol) terpolymers have been obtained by reaction of partially hydrolized poly(vinyl alcohol) with different acid chlorides. The objective is the preparation of polymers with slight differences in their hydrophilic/lipophilic balance and in the interfacial activities of their solutions. The chemical modifications were characterized by means of 1 H NMR and the polymer properties were evaluated in terms of changes in solubility and surface tension. By chemical modification, polymers with low percentage of hydrophobic group were obtained. The water-soluble polymers obtained did not have the surface tension of their solutions altered. The solubility of the modified polymers decreased markedly, even with low contents of hydrophobic groups.

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Liquid crystalline polysurfactant

Cited by 2 publications

References 3 publications

Dielectric Spectroscopy of Pristine and O⁷⁺ Ion Irradiated NCO‐Terminated Polybutadiene‐Based Liquid Crystalline Polyurethane

Dielectric Spectroscopy of Pristine and O⁷⁺ Ion Irradiated NCO‐Terminated Polybutadiene‐Based Liquid Crystalline Polyurethane

Poli(Álcool Vinílico) Modificado com Cadeias Hidrocarbônicas: Avaliação do Balanço Hidrófilo/Lipófilo

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Liquid crystalline polysurfactant

Cited by 2 publications

References 3 publications

Dielectric Spectroscopy of Pristine and O7+ Ion Irradiated NCO‐Terminated Polybutadiene‐Based Liquid Crystalline Polyurethane

Dielectric Spectroscopy of Pristine and O7+ Ion Irradiated NCO‐Terminated Polybutadiene‐Based Liquid Crystalline Polyurethane

Poli(Álcool Vinílico) Modificado com Cadeias Hidrocarbônicas: Avaliação do Balanço Hidrófilo/Lipófilo

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Dielectric Spectroscopy of Pristine and O⁷⁺ Ion Irradiated NCO‐Terminated Polybutadiene‐Based Liquid Crystalline Polyurethane

Dielectric Spectroscopy of Pristine and O⁷⁺ Ion Irradiated NCO‐Terminated Polybutadiene‐Based Liquid Crystalline Polyurethane