Raman Study of Free Volume Effects on Ion Pairs in Polymer Electrolytes

1990 ◽  
Vol 210 ◽  
Author(s):  
L. M. Torell ◽  
S. Schantz ◽  
P. Jacobson
Keyword(s):  
Molecular Weight ◽  
Free Volume ◽  
Polymer Electrolytes ◽  
Ion Pairs ◽  
Polymer Chains ◽  
Cross Linking ◽  
Polymer Complexes ◽  
Solvated Ions ◽  
Entropy Effect ◽  
Raman Study

AbstractIon associations are demonstrated from Raman spectra of the anion symmetric stretch in NaCF3SO3 and LiCF3SO3 containing salt polymer complexes based on PPO and siloxane modified PPO. The observation of increasing amount of ion pairs with increasing molecular weight and temperature can be explained by an entropically driven process. The entropy effect includes contributions from several factors related to transient cross-linking via the cations, conformational entropy of the polymer chains, and free volume dissimilarities between the solvated ions and the macromolecules.

Mechanically robust, readily repairable polymers via tailored noncovalent cross-linking

Science ◽  
2017 ◽  
Vol 359 (6371) ◽  
pp. 72-76 ◽  
Author(s):  
Yu Yanagisawa ◽  
Yiling Nan ◽  
Kou Okuro ◽  
Takuzo Aida
Keyword(s):  
Molecular Weight ◽  
Polymer Chains ◽  
Cross Linking ◽  
Low Molecular Weight ◽  
Structural Element ◽  
Reasonable Time ◽  
Diffusion Dynamics ◽  
Important Challenge ◽  
Sustainable Societies ◽  
Hydrogen Bonded

Expanding the range of healable materials is an important challenge for sustainable societies. Noncrystalline, high-molecular-weight polymers generally form mechanically robust materials, which, however, are difficult to repair once they are fractured. This is because their polymer chains are heavily entangled and diffuse too sluggishly to unite fractured surfaces within reasonable time scales. Here we report that low-molecular-weight polymers, when cross-linked by dense hydrogen bonds, yield mechanically robust yet readily repairable materials, despite their extremely slow diffusion dynamics. A key was to use thiourea, which anomalously forms a zigzag hydrogen-bonded array that does not induce unfavorable crystallization. Another key was to incorporate a structural element for activating the exchange of hydrogen-bonded pairs, which enables the fractured portions to rejoin readily upon compression.

THE ANIONIC POLYMERIZATION OF ALLYL ACRYLATE AND OF ALLYL METHACRYLATE

1966 ◽  
Vol 44 (6) ◽  
pp. 695-702 ◽  
Author(s):  
S. Bywater ◽  
P. E. Black ◽  
D. AM. Wiles
Keyword(s):  
Molecular Weight ◽  
Anionic Polymerization ◽  
Allyl Alcohol ◽  
Polymer Chains ◽  
Cross Linking ◽  
Low Molecular Weight ◽  
Carbonyl Groups ◽  
Double Bonds ◽  
Soluble Product ◽  
Allyl Methacrylate

The low temperature polymerization of allyl acrylate in toluene solution has been investigated with n-butyllithium and 1,1-diphenyl-n-hexyllithium initiators. The latter was also used in a study of the polymerization of allyl methacrylate under the same conditions. The reactions between initiator and monomer were rapid in all cases. More than half of the initiator molecules reacted with monomer acrylic double bonds to start polymer chains, only a few of which grew to a high molecular weight, highly isotactic product. Most of the chains remained as a low molecular weight, precipitant-soluble product. The remaining initiator molecules reacted with the carbonyl groups of the monomers to produce species which could be detected as allyl alcohol, after termination of the reaction with acetic acid. The allyl double bonds were not involved in reactions during polymerization but were presumably responsible for the cross-linking which occurred when the polymers were exposed to air.

Ion Association in Polymer Electrolytes; A Raman Study of Poly (Propylene Oxide) Based Complexes

1988 ◽  
Vol 135 ◽  
Author(s):  
M. Kakihana ◽  
S. Schantz ◽  
L.M. Torell ◽  
L. Borjesson
Keyword(s):  
Salt Concentration ◽  
Ion Pairs ◽  
Ion Association ◽  
Major Effect ◽  
Polymer Complexes ◽  
Ion Interactions ◽  
Different Temperatures ◽  
Component Band ◽  
Raman Study ◽  
Poly Propylene

AbstractRaman spectra of a series of PPO-LiClO4 and PPO-NaCF3SO3 complexes have been obtained for different temperatures and salt concentrations to study the various ion associations of the dopant salt. It was found that ion-ion interactions dramatically influenced the internal symmetric stretching modes ν1 of the anions. Splitting of ν1 into a multicomponent band was observed. The intensity profile of the band was found to change rapidly with salt concentration and temperature. A three component band analysis led to the identification of dissociated ions, ion pairs and multiple ion aggregates, respectively. Increased ion association with increased temperature and/or salt concentration was observed for both LiCIO4- and NaCF3SO3- complexes. It is likely to initiate the phase separation and salt precipitation observed in many salt-polymer complexes at higher temperatures. Considerably stronger ion-ion interaction was observed in the NaCF3SO3-system than in the LiCIO4-complex, which may explain the lower conductivities reported for PPO-NaCF3SO3 electrolytes. The drastic conductivity drop observed in both systems at higher salt concentrations can however only partly be due to a decreased concentration of “free” ions, the major effect being attributed to decreased ion mobility.

Aging Stability of Neoprene Latex. Relation between Cross-Linking and Hydrolysis of Allylic Chlorine

1955 ◽  
Vol 28 (2) ◽  
pp. 628-640
Author(s):  
D. E. Andersen ◽  
Peter Kovacic
Keyword(s):  
Molecular Weight ◽  
Tensile Strength ◽  
Active Sites ◽  
Film Structure ◽  
Polymer Chains ◽  
Active Chlorine ◽  
Cross Linking ◽  
Curing Conditions ◽  
Cross Links ◽  
Hydrolysis Of

Abstract Neoprene polymer chains are cross-linked between active chlorine sites on the chains. There are two types of active sites of different reactivity. It is necessary to use more vigorous curing conditions to actuate the less reactive chlorine. The polymer develops cross-links while aging as a latex as well as during cure, and the decline of tensile strength with latex age may be inversely correlated with the amount of cross-linking during aging. The decline of tensile strength can be prevented by compounding with bis (diethylthiocarbamyl) disulfide. The calculations of the swelling data are not so complete as might be desired, primarily because of difficulty of measuring and interpreting the molecular weight of high-conversion polymers and to some uncertainty in determining μ. It is felt that the qualitative observations are justified, and that they serve to define both the technically important effect of film structure on tensile strength and the mechanism of cure.

scholarly journals Dynamic Responses in Polymer-Clay Gels

2004 ◽  
Vol 840 ◽  
Author(s):  
Elena Loizou ◽  
Lionel Porcar ◽  
Paul Butler ◽  
Matthew Malwitz ◽  
Gudrun Schmidt
Keyword(s):  
Molecular Weight ◽  
Small Angle Neutron Scattering ◽  
Polymer Concentration ◽  
Polymer Chains ◽  
Dynamic Responses ◽  
Cross Linking ◽  
Polymer Molecular Weight ◽  
Continuous Increase ◽  
Shear Orientation ◽  
Clay Platelets

ABSTRACTThe shear orientation of three polymer-clay gels has been investigated by means of small angle neutron scattering (SANS). The gels have the same polymer and clay concentrations but different polymer molecular weight. The polymer is adsorbed to the clay platelets. While long polymer chains can interconnect several platelets shorter polymer chains cannot. Although the polymer concentration is above c* the polymer chain length and cross linking between clay platelets strongly influence their shear orientation which leads to anisotropy in SANS. Our data suggest that the flow is strong enough to enhance and maintain a continuous increase in the shear orientation of the polymer clay gels only when the polymer chains are long enough to interconnect or strongly entangle between platelets.

Cross-Linked αsγt-Chain Hybrids in Plasma Clots Studied by 1D- and 2D Electrophoresis and Western Blotting

1993 ◽  
Vol 70 (03) ◽  
pp. 438-442 ◽  
Author(s):  
B Grøn ◽  
C Filion-Myklebust ◽  
S Bjørnsen ◽  
P Haidaris ◽  
F Brosstad
Keyword(s):  
Molecular Weight ◽  
Monoclonal Antibodies ◽  
Human Plasma ◽  
Western Blotting ◽  
Isoelectric Point ◽  
Factor Xiii ◽  
Cross Linking ◽  
2D Electrophoresis ◽  
Complex Phenomenon ◽  
Fibrinopeptide A

SummaryFibrinogen and fibrin related chains in reduced human plasma as well as the bonds interlinking partially cross-linked fibrin from plasma clots have been studied by means of 1D- and 2D electrophoresis and Western blotting. Immunovisualization of reduced plasma or partially cross-linked fibrin with monoclonal antibodies specific for the α-chains or the γ-chains have shown that several bands represent material belonging to both chains. In order to decide whether these bands constitute αγ-chain hybrids or superimposed α- and γ-chain dimers, the cross-linked material was separated according to both isoelectric point (pI) and molecular weight (MW) using Pharmacia’s Multiphor II system. Western blotting of the second dimension gels revealed that partially cross-linked fibrin contains αsγt-chain hybrids and γ- polymers, in addition to the well-known γ-dimers and α-polymers. The main αsγt-chain hybrid has a pI between that of the α- and the γ-chains, a MW of about 200 kDa and contains Aα-chains with intact fibrinopeptide A (FPA). It was also observed that soluble fibrinogen/fibrin complexes as well as partially cross-linked fibrin contain degraded α-dimers with MWs close to the γ-dimers. These findings demonstrate that factor XIII-catalyzed cross-linking of fibrin is a more complex phenomenon than earlier recognized.

Dynamics of Ion Locking in Doubly Polymerized Ionic Liquids

2020 ◽  
Author(s):  
Swati Arora ◽  
Julisa Rozon ◽  
Jennifer Laaser
Keyword(s):  
Dielectric Constant ◽  
Ionic Liquid ◽  
Ionic Liquids ◽  
Ion Pairs ◽  
Polymer Chains ◽  
Ion Motion ◽  
Charged Species ◽  
Broadband Dielectric Spectroscopy ◽  
Covalently Linked ◽  
Insight Into

<div>In this work, we investigate the dynamics of ion motion in “doubly-polymerized” ionic liquids (DPILs) in which both charged species of an ionic liquid are covalently linked to the same polymer chains. Broadband dielectric spectroscopy is used to characterize these materials over a broad frequency and temperature range, and their behavior is compared to that of conventional “singly-polymerized” ionic liquids (SPILs) in which only one of the charged species is attached to the polymer chains. Polymerization of the DPIL decreases the bulk ionic conductivity by four orders of magnitude relative to both SPILs. The timescales for local ionic rearrangement are similarly found to be approximately four orders of magnitude slower in the DPILs than in the SPILs, and the DPILs also have a lower static dielectric constant. These results suggest that copolymerization of the ionic monomers affects ion motion on both the bulk and the local scales, with ion pairs serving to form strong physical crosslinks between the polymer chains. This study provides quantitative insight into the energetics and timescales of ion motion that drive the phenomenon of “ion locking” currently under investigation for new classes of organic electronics.</div>

Electrogeneration of Conducting Poly(α-tetrathiophene). Effect of Solution Stirring and Detection of Linear Oligomers

2003 ◽  
Vol 68 (7) ◽  
pp. 1326-1344 ◽  
Author(s):  
Francesc Estrany ◽  
Ramon Oliver ◽  
Esther García ◽  
Esther Gualba ◽  
Pere-Lluís Cabot ◽  
...  
Keyword(s):  
Ion Pairs ◽  
Polymer Chains ◽  
Polymerization Process ◽  
Anodic Process ◽  
Cathodic Peak ◽  
Linear Chains ◽  
Monomer Solution ◽  
Ir Analysis ◽  
Microscopy Images ◽  
Tof Ms

The anodic oxidation of α-tetrathiophene on Pt was studied in a 1.0 mM monomer solution in 0.1 M LiClO4 in 45:35:20 acetonitrile/ethanol/DMF. Three consecutive oxidation peaks were detected by cyclic voltammetry, along with a cathodic peak related to the reduction of electroactive polarons formed during the first anodic process. Uniform, adherent, insoluble and black polymer films were obtained by chronoamperometry at 1.000 V vs Ag|AgCl corresponding to the first oxidation-polymerization process. Stirring of monomer solution promotes the production of polymer, favoring the oxidation of polymer chains with the incorporation of more doping ClO4- ions and ion pairs of Li+ClO4- in their monomeric units. The conductivity of the polymer obtained under stirring was three orders of magnitude higher than that synthesized from a quiescent solution. The scanning electron microscopy images also showed much more uniform films under stirring. This behavior points to the existence of less crosslinking in the polymer and the production of longer linear chains when the solution is stirred. IR analysis of these materials confirmed the formation of crosslinked chains with predominance of β-β linkages. Short linear oligomers such as the dimer, trimer and tetramer were detected in all polymers by MALDI-TOF-MS, thus showing a radical polycondensation as initial electropolymerization mechanism. A larger proportion of linear oligomers is formed under solution stirring.

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