Molecular Mechanism of Solvent-Induced Crystallization of Syndiotactic Polystyrene Glass. 1. Time-Resolved Measurements of Infrared/Raman Spectra and X-ray Diffraction

Tashiro, Kohji; Ueno, Y.; Yoshioka, and Akiko; Kobayashi, Masamichi

doi:10.1021/ma001659s

Cited by 132 publications

(139 citation statements)

References 40 publications

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“…For example, crystallization of amorphous syndiotacic-polystyrene induced was induced by vapor of toluene [21]. It may offer the key to attain the crystallization of PLA without whitening.…”

Section: Introductionmentioning

confidence: 99%

Crystallization of Amorphous Poly(Lactic Acid) Induced by Vapor of Acetone to Form High Crystallinity and Transparency Specimen

Naga¹,

Yoshida²,

Noguchi³

et al. 2013

OJPChem

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Crystallization of amorphous poly(lactic acid) (PLA) was investigated by exposing to vapor of acetone. The vapor of acetone induced crystallization of the amorphous PLA effectively. It took about 24 min to complete the crystallization of a 1 cm × 2 cm × 0.55 mm specimen at 25˚C. The crystallization rate increased with increasing of conducting temperature. The crystallization method yielded high crystallinity about 40%, which was almost equal to that attained by annealing or immersion methods conducted as references. The specimens crystallized by the vapor showed higher transparency than those prepared by the reference methods. The crystallization was induced by diffusion of acetone into the amorphous phase of PLA, and polarized optical photomicrographs cleared that the diffusion obeyed Fick type diffusion.

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Section: Introductionmentioning

confidence: 99%

Crystallization of Amorphous Poly(Lactic Acid) Induced by Vapor of Acetone to Form High Crystallinity and Transparency Specimen

Naga¹,

Yoshida²,

Noguchi³

et al. 2013

OJPChem

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“…Kobayashi and his coworkers revealed the characteristic vibrational modes for these conformations using the infrared and Raman spectroscopies. [9][10][11][12][13] It is worth noting that the formation of the modifications with the t 2 g 2 sequence requires the assistance of an organic solvent. Several methods are known to obtain the t 2 g 2 crystal forms, i.e., casting from an organic solution, soaking the glassy sPS in an organic non-solvent, and exposing the glassy sPS in vapor of an organic solvent.…”

mentioning

confidence: 99%

Crystallization Condition of Glassy Syndiotactic Polystyrene in Supercritical CO2

Nakaoki

Fukuda

Nakajima

et al. 2003

Polym J

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ABSTRACT:Polymorphism of syndiotactic polystyrene (sPS) induced by supercritical CO 2 (scCO 2 ) was investigated as functions of temperature and pressure by using infrared spectroscopy and X-ray diffraction. When a glassy sPS was incubated in scCO 2 at 18 MPa, a modification with the trans-trans-gauche-gauche (t 2 g 2 ) conformation appeared between 40• C and 80• C, and the planar zigzag form appeared above 60• C. Both forms coexisted between 60• C and 80• C. Below the critical temperature of CO 2 (31.1 • C) no crystallization occurred at any pressure. When the pressure of CO 2 is below the critical pressure (7.2 MPa), the t 2 g 2 form did not appear at any temperature but the planar zigzag form appeared above 90• C. These results indicate that incubation in supercritical CO 2 is necessary for the formation of the t 2 g 2 form. On the other hand, the planar zigzag form was obtained irrespective of the physical states of CO 2 , but depended on the incubation temperature and pressure. This indicates that the conformational stability of the planar zigzag form depends only on the thermal factors. The crystallization temperature into the planar zigzag form decreased with increasing pressure of CO 2 due to the plasticizer effect of CO 2 . KEY WORDS Crystallization / Syndiotactic Polystyrene / Supercritical CO 2 / Infrared Spectroscopy / Syndiotactic polystyrene (sPS) exhibits polymorphism. So far four crystal modifications and two mesomorphic phases have been reported, since Ishihara et al. 1 succeeded the synthesis of highly syndiotactic polystyrene. [2][3][4][5][6][7][8] The molecular conformation of the α and β forms is planar zigzag but that of the γ and δ forms is t 2 g 2 . Kobayashi and his coworkers revealed the characteristic vibrational modes for these conformations using the infrared and Raman spectroscopies. [9][10][11][12][13] It is worth noting that the formation of the modifications with the t 2 g 2 sequence requires the assistance of an organic solvent. Several methods are known to obtain the t 2 g 2 crystal forms, i.e., casting from an organic solution, soaking the glassy sPS in an organic non-solvent, and exposing the glassy sPS in vapor of an organic solvent. For example, chloroform, benzene, toluene, and other many aromatic compounds were found to induce the δ-form. 5, 9 Since the δ-form is one of the host-guest type crystals formed by the sPS chains and solvent molecules, the cavity created by the sPS chains in the crystal is believed to play an important role to form the complex structure. 8,14 The γ-form also takes the t 2 g 2 conformation but is formed without solvents. 5,11 These crystal structures have been investigated in terms of various methods. Among them, the infrared spectroscopy is very sensitive to conformational changes and provides information not only on the lo- † To whom correspondence should be addressed.cal vibrations such as the stretching and bending modes but also on the molecular symmetry defined by the factor group analyses. The symmetries of the planar zigzag and the t 2 g ...

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“…This range is known to be sensitive to sPS conformation. 1,25 It can be seen from Figure 1 that the same strong vibrational bands near 572, 549, and 536 cm À1 for all solvents were observed and these bands became larger with increasing time. These bands are characteristic of the conformation TTGG, indicating that the sPS chains gather together into the helical structure in the sPS/organic solvent gel.…”

Section: Conformation Of Sps Chains In Gelmentioning

confidence: 71%

Solvent Effect on Junction Size in Syndiotactic Polystyrene Physical Gel

Shimizu

Wakayama

Wada

et al. 2005

Polym J

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ABSTRACT:In order to estimate the junction point size of syndiotactic polystyrene (sPS) physical gels formed in chloroform, toluene, benzene, and o-dichlorobenzene, gel-melting temperatures were measured as a function of polymer concentration. The size in number of styrene units was estimated with the aid of the Tanaka and Stockmayer theory (TS theory), which is based upon the conjecture that junction points of a gel are aggregates comprised of units in length and sequences in cross section. According to measurement of in situ FT-IR, the junction points of sPS/ organic solvent gels were suggested to be aggregates of sPS chains with helical structure of TTGG conformation regardless of the difference in solvents. Quantitative analysis by the TS theory led to the results that the size was little dependent upon the sPS molecular weight for each sPS/organic solvent system. On the other hand, the size was strongly affected by solvents, i.e., in sPS/o-dichlorobenzene gel was the largest among the solvents used in the present study, while that in sPS/chloroform gel was the smallest. This solvent effect on the junction point size probably arises from the difference in magnitude of polymer/solvent interaction. [DOI 10.1295/polymj.37.294] KEY WORDS Syndiotactic Polystyrene / Polystyrene / Thermoreversible Gel / Junction Size / Gel-melting Temperature / Time-resolved FT-IR / Syndiotactic polystyrene (sPS) is of considerable scientific and industrial interest as a rigid high performance semicrystalline material. It is known that sPS polymer has two types of molecular chain conformations in its crystalline region: one is the all-trans planar zigzag structure (TT), and the other is the helical conformation (TTGG). 1-5Like other crystalline or semicrystalline polymers, sPS polymer also converts to thermoreversible gel in suitable organic solvents such as toluene or chloroform. Kobayashi et al. investigated the gelation process of sPS with time-resolved Fourier transform infrared (FT-IR) spectroscopy and showed that highly ordered TTGG conformations are formed on gelation. 6 Recent studies in the temperature-concentration phase diagrams of sPS gels have suggested that solvent molecules are intercalated between sPS chains in the TTGG conformation, and the number of solvent molecules involved is dependent on the gelation solvent.7-11 The ordered TT conformation was observed on gelation of sPS in big size solvent like octadecyl benzoate.12 Time-resolved small-angle neutron scattering (SANS) experiments also showed that the gelnetwork structure formation occurred in parallel to the conformational ordering of sPS chains. 13The thermoreversible gelation of highly stereoregular polymers such as sPS and syndiotactic poly-(methyl methacrylate) is considered to proceed in two steps:14-16 A first step is an intramolecular coil-tohelix transition; This change in molecular conformation is then followed by an intermolecular association of multiple helix segments, which leads to the formation of network structure. This gelation mechanism is ...

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Molecular Mechanism of Solvent-Induced Crystallization of Syndiotactic Polystyrene Glass. 1. Time-Resolved Measurements of Infrared/Raman Spectra and X-ray Diffraction

Cited by 132 publications

References 40 publications

Crystallization of Amorphous Poly(Lactic Acid) Induced by Vapor of Acetone to Form High Crystallinity and Transparency Specimen

Crystallization of Amorphous Poly(Lactic Acid) Induced by Vapor of Acetone to Form High Crystallinity and Transparency Specimen

Crystallization Condition of Glassy Syndiotactic Polystyrene in Supercritical CO2

Solvent Effect on Junction Size in Syndiotactic Polystyrene Physical Gel

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