Structural phase transitions of syndiotactic polystyrene

Gowd, E. Bhoje; Tashiro, Kohji; Ramesh, C.

doi:10.1016/j.progpolymsci.2008.11.002

Cited by 165 publications

(143 citation statements)

References 141 publications

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“…IR and VCD measurements were recorded using a commercial Bruker Tensor 27 FTIR spectrometer coupled to a PMA50 external module, (needed to double modulate the Infrared radiation) using a linear KRS5 polarizer, a ZnSe 50 KHz photoelastic modulator (PEM, by HINDS) with a proper antireflecting coating, an optical filter (transmitting below 2000 cm 21 ) and a narrow band MCT (Mercury Cadmium Telluride) detector. All VCD spectra were recorded for 5 min of data collection time, at 4 cm 21 resolution.…”

Section: Methodsmentioning

confidence: 99%

“…Large circular dichroism values are observed not only for the peaks of the nonracemic guests e.g., for carvone at 1667 cm 21 and for limonene at 1644, and 888 (labeled as g and g 0 in Figures 2B and 2D, respectively), but also for many polymer host peaks, for instance at 1601, 1352, 1169, and 1067 cm 21 . The VCD spectra of Figures 2B and 2D also show that enantiomers of carvone and limonene labeled by the same configurational sign, which exhibit sterically similar structures (Scheme 1), present the same sign for each CD peak.…”

Section: Vcd Measurementsmentioning

confidence: 99%

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Induced vibrational circular dichroism and polymorphism of syndiotactic polystyrene

2010

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The intense circular dichroism (CD) phenomena, as induced in amorphous samples of syndiotactic polystyrene (s-PS) by cocrystallization with nonracemic volatile guest molecules (carvone and limonene), have been investigated by Vibrational Circular Dichroism (VCD) measurements and X-ray diffraction characterizations. Moreover, the stability of these CD phenomena after thermal and solvent treatments, leading to different polymorphic crystalline phases of s-PS, has been studied. The CD phenomena remain stable not only after guest extraction but also after thermal annealing procedures leading to the helical γ phase or to the transplanar α phase. The CD phenomena are instead reduced for the solvent treatments involving at least partial dissolution and crystallization that lead to the helical ε phases and even lost for thermal treatments involving melting and crystallization that lead to the β phase. The reported results indicate that the intense CD phenomena observed for s-PS films are due to a supramolecular chirality associated with the native cocrystal morphology.

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Section: Methodsmentioning

confidence: 99%

Section: Vcd Measurementsmentioning

confidence: 99%

Induced vibrational circular dichroism and polymorphism of syndiotactic polystyrene

2010

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“…It is believed that small cavities could be found between the PS chains [8]. Therefore, it is likely that as time proceeds, water is able to penetrate through the cavities of the PS chains and eventually allow more pores to be formed [23].…”

Section: Aunp@pspaa Incubation In Watermentioning

confidence: 99%

“…Secondly, the poly(acrylic acid) (PAA) block helps maintain charge-charge repulsion, and hence allows the AuNP@PSPAA to maintain its stability in water [6]. While pores or voids may be found in the PS domain when placed in water [8], AuNP@PSPAAwere found to resist cyanide etching for months [9]. This suggests that limited or low ionic diffusion of ions occurred across the polymer shell.…”

Section: Introductionmentioning

confidence: 99%

Probing Ionic Diffusion Dynamics through the Modulation of Polymer Shell Using Surface-Enhanced Raman Spectroscopy

Song¹,

Phua²,

Xu³

2017

J Nanomed Nanotechnol

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“…sPS is regarded as a new low-cost engineering polymer with various desirable properties, such as high melting temperature (270 1C), fast crystallization rate, low dielectric constant, low permeability to gases and good chemical resistance. [24][25][26] Several drawbacks can, however, restrict its practical use: its brittleness, a disadvantage in applications where mechanical properties are important; the lack of polar groups for adhesion and compatibility with other polymers; and the need to process sPS at high temperatures. Recently, several attempts have been made to improve the physical properties and processability of sPS by several procedures.…”

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confidence: 99%

Exfoliated syndiotactic polystyrene-graft-poly(methyl methacrylate)/montmorillonite nanocomposite prepared by solvent blending

Jaymand

2011

Polym J

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This study aims to explore an effective route for the graft copolymerization of methyl methacrylate (MMA) monomer onto syndiotactic polystyrene (sPS) using free-radical polymerization, and the effects of an organophilic montmorillonite on the final properties of graft copolymer samples. For this purpose, the chlorine groups of a-phenyl-chloro-acetylated sPS were converted to 9-decen-1-oxy groups by a substitution nucleophilic reaction in the presence of a solvent composed of 9-decen-1-ol moiety, sodium hydride (NaH) and dry N,N-dimethylformamide. The vinyl-terminated sPS multicenter macromonomer (VsPSM) obtained was used in free-radical copolymerization with MMA monomer in a heterogeneous process to yield a graft copolymer (sPS-graftpoly(methyl methacrylate) (sPS-g-PMMA)). The structure of VsPSM and sPS-g-PMMA were determined by 1 H nuclear magnetic resonance and Fourier transform infrared spectroscopy. Thereafter, organophilic MMT was obtained after being treated with hexadecyl trimethyl ammonium chloride salt by an ion-exchange process. Finally, the sPS-g-PMMA/MMT nanocomposite was prepared by a solution intercalation method. X-ray diffraction and transmission electron microscopy were used to confirm nanocomposite formation. It was found that the addition of only a small amount of organoclay (3 wt%) was enough to improve the thermal stabilities and properties of the nanocomposite. Polymer Journal (2011) 43, 901-908; doi:10.1038/pj.2011.79; published online 7 September 2011Keywords: free-radical polymerization; graft copolymer; macromonomer; montmorillonite; nanocomposite; poly(methyl methacrylate); syndiotactic polystyrene INTRODUCTION Nanocomposites are defined as materials in which the particle size of the dispersed phase is in the nanometer range in at least one dimension. Organic-inorganic hybrids based on layered inorganic compounds, such as clays and organic polymers, have been studied because of their exceptional properties, such as increased modulus, strength, reduced gas permeability and enhanced thermal stability. [1][2][3][4][5] The dispersion of the silicate layers in the polymer matrix is improved by replacing the metal cations in the clay (such as sodium MMT; Na + -MMT) with ions bearing an aliphatic chain to compatibilize the silicate. This compatibilization enhances the silicate's interaction with the polymer by enlarging the interlayer, and the compatibilized clay is known as an organoclay. [6][7][8][9] Although complete compatibility between the long aliphatic chain of the organic modifier and the polymer matrix may be desirable for better dispersion of the clay, it appears that the modification of the clay by the introduction of surfactants to obtain better compatibility is less important than the modification of the polymer matrix by the introduction of polar groups. Polymers containing polar groups capable of associative interactions, such as Lewis acid/base interactions or hydrogen bonding, lead to intercalation of polymer chains in the silicate layers. To improve the polarizability or hy...

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Structural phase transitions of syndiotactic polystyrene

Cited by 165 publications

References 141 publications

Induced vibrational circular dichroism and polymorphism of syndiotactic polystyrene

Induced vibrational circular dichroism and polymorphism of syndiotactic polystyrene

Probing Ionic Diffusion Dynamics through the Modulation of Polymer Shell Using Surface-Enhanced Raman Spectroscopy

Exfoliated syndiotactic polystyrene-graft-poly(methyl methacrylate)/montmorillonite nanocomposite prepared by solvent blending

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