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The δ-clathrate forms of syndiotactic polystyrene (s-PS) containing a homologous series of guests characterized by an increasing molecular volume (n-alkanes ranging from n-pentane to n-dodecane) have been investigated. The present analysis allows concluding that the volume of the guest plays a crucial role in the choice of the type of δ-clathrate that can be obtained. As a matter of fact, longer n-alkanes,...
Conformational behaviors of syndiotactic polystyrene (sPS) in chloroform were investigated by detecting its concentration dependence of intrinsic fluorescence in the range from 25 to −62 °C. For the dimer emission, the coexistence of T-shaped configuration with sandwich configuration was observed and the contribution of sandwich configuration increases with increasing sPS concentration in the system...
The induced circular dichroism (ICD) syndiotactic polystyrene (sPS) chiral films in sPS δ phase were prepared and the chirality of the ICD sPS films upon annealing at different temperature was investigated. The sPS δ crystals in the ICD films transform into γ and then into α crystals as those of achiral sPS δ crystals during annealing at different temperature. The CD signal intensity at λ of 200nm...
A well-dispersed multiwall carbon nanotube (MWCNT)/syndiotactic polystyrene (sPS) composite was prepared by simple in-situ polymerization of styrene using pentamethylcyclopentadienyltitanium(IV) trimethoxide (Cp*Ti(OMe) 3 ) attached to the shortened and functionalized MWCNT (f-MWCNT). The attachment of Cp*Ti(OMe) 3 to the f-MWCNT was confirmed by thermogravimetric analysis, X-ray photoelectron...
Three different co-crystalline phases of syndiotactic polystyrene (s-PS) with azobenzene have been prepared and structurally characterized. The triclinic δ-clathrate phase is characterized by a styrene-monomeric-unit/guest ratio (SU/G) equal to 8/1 while the δ-intercalate phase is characterized by SU/lG = 4/1. The orthorhombic ε-clathrate phase allows stacking of a variable number of guest molecules...
In order to improve the thermal stability of δ e form of sPS that possesses nanoporous structure, benzoylation of the phenyl groups was adopted and performed by solution procedure or solid procedure. The solution procedure involves initial benzoylation of sPS in solution and then preparing δ e form by solvent induction of benzoylated sPS; the solid procedure means benzoylation of δ...
This work investigated the effects of multi-walled carbon nanotubes (MWCNTs) on density, surface area, compressive strength, and electrical conductivity of syndiotactic polystyrene (sPS) aerogels. The non-covalently modified MWCNTs were dispersed in sPS solution before thermo-reversible gelation of the polymer. The aerogels were obtained by exchanging the solvent with liquid carbon dioxide and by...
In-situ time-resolved small angle neutron scattering is applied to the guest exchange phenomenon in the co-crystals of syndiotactic polystyrene for the first time, exploiting the significant difference in coherent scattering length between two isotopologues, fully protonated and deuterated compounds, employed as originally-occupying and subsequently-occupying guests. The vapor-induced guest exchange...
The starting morphology used for the preparation of the syndiotactic polystyrene (sPS)/solvent complex, has a significant role in facilitating the phase transitions of the host structure upon guest exchange process. This effect was studied on the structural changes of sPS, using guest exchange process, with a series of n-alkanes, and analyzed by X-ray diffraction and Fourier transform infrared spectroscopy...
The conditioning history of amorphous syndiotactic polystyrene (sPS) in mild supercritical CO2 (scCO2) changes significantly the thermal behavior and crystal phase transformation of sPS in further thermal treatment by inducing the formation of helical segments. The results of differential scanning calorimetry and temperature-dependent Fourier transform infrared spectroscopy show that polymer chains...
The role of host preparation method on the structural phase transition of syndiotactic polystyrene (sPS) after the guest exchange process has been thoroughly investigated in our previous study using a series of n-alkanes [Polymer 2013; 54:6617-27]. In addition to the host preparation method, we have found that guest molecules used for the guest exchange process also have a significant role in facilitating...
The α″ phase of syndiotactic polystyrene (α″sPS) is a frustrated “superstructure” that houses three triplets (three clusters of three chains, thus nine chains) in a trigonal unit-cell. The hk0 electron diffraction pattern of α″sPS single crystals displays, in addition to sharp spots, a number of diffuse spots located at 1/3 and 2/3 between the sharp spots. The diffuse spots correspond to the intersection...
Melt-crystallization of syndiotactic polystyrene (sPS) is studied using simultaneous small/wide angle X-ray scattering (SAXS/WAXS). Emergence, intensification, and saturation of WAXS reflections within 120 s at isothermal crystallization temperature Tc = 250 °C after quenching from 300 °C illustrate crystallinity development through successive nucleation of instantaneously stabilized crystallites...
The crystallization behaviour of syndiotactic polystyrene (sPS) and benzoylated sPS (BzsPS) was investigated by POM, DSC and XRD. The results suggest β form of sPS has higher equilibrium melting temperature Tm0 and the fold surface free energy σe than α form. With increasing benzoylation degree the growth rates and Tm0 of two forms decrease, but their Tm0 decrement is very close; the σe of β form...
Skin layers are ubiquitous in synthesis of macro- and mesoporous polymer aerogel monoliths, are much denser than the bulk materials, and can potentially impact several properties of aerogels. This study evaluates the effects of skin layers on the values of air permeability in aerogel monoliths of syndiotactic polystyrene (sPS) prepared from thermo-reversible gelation of sPS solutions followed by supercritical...
Thermal effects on the strain-induced structural transition from β-form to α-form crystals of syndiotactic polystyrene (sPS) were investigated by changing the stretching temperature and the annealing temperature. When sPS was stretched at lower temperature (near the glass transition temperature (Tg) of sPS (∼130 °C)), the crystalline structural transition was incomplete, producing fragmented β-form...
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