The Flory-Huggins Interaction Parameter and Thermoreversible Gelation of Poly(vinylidene fluoride) in Organic Solvents

Okabe, Masaru; Wada, Risei; Tazaki, Michiko; Homma, Takeshi

doi:10.1295/polymj.35.798

Cited by 41 publications

(34 citation statements)

References 29 publications

(25 reference statements)

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“…To solve for M c , these equations require the polymer volume fraction of the swollen gel (V pol ), the molar volume of the solvent (V 0 ), the density of the polymer (r pol ), the Huggins solvent-polymer interaction parameter (m), the swelling factor (f) and the density of the solvent (r solv )-in this case cyclohexanone. Tazaki et al (2000) and Okabe et al (2003) have determined the Flory-Huggins interaction parameters (m) for PVDF homopolymer and a 12% HFP copolymer in cyclohexanone across a wide temperature range. Using their data, values of 0.3 and À0.3 were obtained for PVDF and 12% HFP copolymer, respectively.…”

Section: Sol-gel Analysismentioning

confidence: 99%

Evaluation of vinylidene fluoride polymers for use in space environments: Comparison of radiation sensitivities

Dargaville

Celina

Clough

2006

Radiation Physics and Chemistry

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Section: Sol-gel Analysismentioning

confidence: 99%

Evaluation of vinylidene fluoride polymers for use in space environments: Comparison of radiation sensitivities

Dargaville

Celina

Clough

2006

Radiation Physics and Chemistry

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“…27,28 We have also shown that T g m of poly(vinylidene fluoride) or poly(butylene succinate) gels increases with increasing 12 . 29,30 In view of these previous results, the junction size in sPS gels is thought to have a close relationship to the sPS-solvent interaction parameter though we have not measured 12 yet. That is to say, the size is presumed to become larger with increasing 12 .…”

Section: Junction Point Size Of Gelmentioning

confidence: 69%

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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“…A large difference in solubility parameters between PVdF and the gelation solvent would result in decreased swelling ratios, leading to an increase in T m g . We previously reported that the T m g values of PVdF gels in the absence of lithium salts 16 and those of poly(butylene succinate) gels 25 increase with an increase in the polymer-solvent interaction parameter. …”

Section: Gel-melting Temperaturementioning

confidence: 99%

“…[12][13][14][15] In addition, we experimentally estimated the Flory-Huggins interaction parameters (w 12 ) between PVdF and the organic solvents over a wide temperature range using inverse gas chromatography and then clarified the correlation between the thermoreversible gelation of a PVdF solution and the magnitude of w 12 . 16 Here, we report the results of a preliminary study of the gelation process and the structural morphology of a PVdF gel in the presence of a lithium salt, LiBF 4 . The morphology of the PVdF gel was studied by scanning electron microscopy (SEM).…”

Section: Introductionmentioning

confidence: 99%

Sol-gel transitions of poly(vinylidene fluoride) in organic solvents containing LiBF4

Shimizu

Arioka

Ogawa

et al. 2011

Polym J

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Poly(vinylidene fluoride) (PVdF) dissolved in organic solvents containing lithium tetrafluoroborate (LiBF 4 ) forms stable gels when the solution is cooled to room temperature. Here, we describe the effects of LiBF 4 concentration and different gelation solvents on the gelation process, and characterize the resulting structural morphology using several techniques. Diethyl carbonate (DEC), propylene carbonate (PC) and c-butyrolactone (GBL) were used as gelation solvents. Time-resolved Fourier transform infrared spectroscopic measurements showed that the conformational transition from TGT G to T 3 GT 3 G occurred with the addition of lithium salts to the PVdF/DEC gel. In addition, PVdF produces thermoreversible gels in GBL and PC containing LiBF 4 , by assuming a T 3 GT 3 G conformation regardless of the LiBF 4 concentration. Scanning electron microscopy studies have indicated the presence of spherulites in the gels. Spherulite size decreased with increasing LiBF 4 concentration, whereas gel-melting temperatures increased with an increase in LiBF 4 concentration. These results indicate that gelation of PVdF in the presence of LiBF 4 occurs as polymer chains assuming the T 3 GT 3 G conformation, imparting the resulting gels with increased thermal stability. Polymer Journal (2011) 43, 540-544; doi:10.1038/pj.2011.21; published online 13 April 2011Keywords: lithium ion; molecular conformation; polymer gel electrolyte; poly(vinylidene fluoride); thermoreversible gel INTRODUCTION Polymer electrolytes have attracted much attention in lithium-battery technology because they enable fabrication of safe and reliable highenergy, high-power secondary lithium batteries. 1 Typical examples of polymer electrolytes include complexes of a lithium salt (LiX) with PEO (polyethylene oxide). The conductivity of PEO-LiX electrolytes reaches practically useful values of B10 À4 S cm À1 at temperatures of 60-80 1C but decreases to 10 À7 S cm À1 at room temperature. 2 Decrease in the conductivity on cooling is because fast ion transport occurs only in the amorphous state of the polymer.The most promising approach for improving conductivity at room temperature is to immobilize a highly conductive liquid electrolyte within a polymer matrix. This type of electrolyte is called a polymer gel electrolyte. This system demonstrates high ionic conductivity at room temperature with sufficient mechanical strength. 3,4 Among the matrices used for polymer gel electrolytes are PVdF, 5,6 poly(methyl methacrylate), 7,8 and poly(acrylonitrile). 9,10 Gel electrolytes based on PVdF are of great interest because of their good thermal, mechanical and electrochemical stability. Recent studies have shown that the ionic conductivity of PVdF gel electrolytes is related to the morphology of the gel. 11 However, a detailed characterization of these gels with regard to the gelation process and structural morphology has not been undertaken. In a previous study, we reported our investigation of the gelation process of PVdF in a number of organic solvents without a lith...

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The Flory-Huggins Interaction Parameter and Thermoreversible Gelation of Poly(vinylidene fluoride) in Organic Solvents

Cited by 41 publications

References 29 publications

Evaluation of vinylidene fluoride polymers for use in space environments: Comparison of radiation sensitivities

Evaluation of vinylidene fluoride polymers for use in space environments: Comparison of radiation sensitivities

Solvent Effect on Junction Size in Syndiotactic Polystyrene Physical Gel

Sol-gel transitions of poly(vinylidene fluoride) in organic solvents containing LiBF4

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