Study of the kinetics of mushroom-to-brush transition of charged polymer chains

Polymer ◽  
2006 ◽  
Vol 47 (9) ◽  
pp. 3157-3163 ◽  
Author(s):  
Guangming Liu ◽  
Lifeng Yan ◽  
Xi Chen ◽  
Guangzhao Zhang
Keyword(s):  
Polymer Chains ◽  
Charged Polymer ◽  
Kinetics Of

Simulations of High-Strain Electrostrictive Chlorinated Terpolymers

2003 ◽  
Vol 785 ◽  
Author(s):  
George J. Kavarnos ◽  
Thomas Ramotowski
Keyword(s):  
Vinylidene Fluoride ◽  
High Strain ◽  
Polymer Chains ◽  
X Ray Diffraction ◽  
X Ray ◽  
Lamellar Structures ◽  
Annealing Conditions ◽  
Poly Vinylidene Fluoride ◽  
Electromechanical Responses ◽  
Kinetics Of

ABSTRACTChlorinated poly(vinylidene fluoride/trifluoroethylene) terpolymers are remarkable examples of high strain electrostrictive materials. These polymers are synthesized by copolymerizing vinylidene fluoride and trifluoroethylene with small levels of a third chlorinated monomer. The electromechanical responses of these materials are believed to originate from the chlorine atom, which, by its presence in the polymer chains and by virtue of its large van der Waals radius, destroys the long-range crystalline polar macro-domains and transforms the polymer from a normal to a high-strain relaxor ferroelectric. To exploit the strain properties of the terpolymer, it is desirable to understand the structural implications resulting from the presence of the chlorinated monomer. To this end, computations have been performed on model superlattices of terpolymers using quantum-mechanical based force fields. The focus has been on determining the energetics and kinetics of crystallization of the various polymorphs that have been identified by x-ray diffraction and fourier transform infrared spectroscopy. The chlorinated monomer is shown to act as a defect that can be incorporated into the lamellar structures of annealed terpolymer without a high cost in energy. The degree of incorporation of the chlorinated monomer into the crystal lattice is controlled by annealing conditions and ultimately determines the ferroelectric behavior of the terpolymers.

Kinetics of polymer crystallization - II. Growth régimes

1988 ◽  
Vol 416 (1851) ◽  
pp. 463-476 ◽  
Keyword(s):  
Growth Rate ◽  
Continuum Model ◽  
Continuum Limit ◽  
Polymer Chains ◽  
Lamellar Crystal ◽  
Folding Rate ◽  
Edge Roughness ◽  
State Growth ◽  
Kinetics Of ◽  
The Continuum

From the models of paper I, exact expressions are found for the steady-state growth rate of a portion of the edge of a lamellar crystal in terms of the number of polymer segments M in the portion, the nucleation rate α on the edge and the folding rate v of polymer chains. Both hexagonal and square crystal structures are analysed. Simpler expressions are given in various limiting cases or régimes. One such régime is the continuum model of Bennett et al. (J. statist. Phys . 24, 419 (1981)). We find that the growth rates in our models differ substantially from this continuum limit when edge roughness is significant. The continuum growth rate provides an exact upper bound on the growth rate in Frank’s model (Frank, F. C. J. Cryst. Growth 22, 233 (1974)), which is sometimes exceeded by Frank’s approximation.

Morphology, Crystalline Structure and Isothermal Crystallization Kinetics of Polybutylene Terephthalate/Montmorillonite Nanocomposites

2005 ◽  
Vol 13 (1) ◽  
pp. 61-71 ◽  
Author(s):  
Defeng Wu ◽  
Chixing Zhou ◽  
Xie Fan ◽  
Dalian Mao ◽  
Zhang Bian
Keyword(s):  
Activation Energy ◽  
Crystallization Kinetics ◽  
Crystallization Temperature ◽  
Isothermal Crystallization ◽  
Polymer Chains ◽  
Isothermal Crystallization Kinetics ◽  
Clay Particles ◽  
Nucleation Sites ◽  
Kinetics Of ◽  
Montmorillonite Nanocomposites

The melt intercalation method was employed to prepare poly(butylene terepathalate)/montmorillonite nanocomposites, and their microstructure was characterized by wide angle X-ray diffraction and transmission electron microscopy. The XRD results showed that the crystalline plane such as (010), (111), (100) was smaller than that of pristine PBT, which indicates that the crystallite size of PBT in the nanocomposites could be diminished by adding clay. Moreover, the isothermal crystallization kinetics of PBT and PBT/MMT nanocomposites was investigated by differential scanning calorimetry (DSC). During isothermal crystallization, the development of crystallinity with time was analysed by the Avrami equation. The results show that very small amounts of clay dramatically increased the rate of crystallization and high clay concentrations reduced the rate of crystallization at the low crystallization temperatures. At low concentrations of clay, the distance between dispersed platelets was large so it was relatively easy for the additional nucleation sites to incorporate surrounding polymer, and the crystal nucleus was formatted easily. However, at high concentrations of clay, the diffusion of polymer chains to the growing crystallites was hindered by large clay particles, despite the formation of additional nucleation sites by the clay layers. At the higher crystallization temperature, the crystallization of the nanocomposites was slower than that of the pure PBT under the experimental conditions, which means that with the increase in chains mobility at the high crystallization temperature, the crystal nuclei are harder to format, and the hindering effect of clay particles on the polymer chains was stronger than the nucleating effect of the layers. In addition, the activation energies of crystallization for PBT and its nanocomposites were calculated by the Arrhenius relationship, and the results showed that the nanocomposites with a low clay content had the lower activation energy values than PBT, while high amounts of clay increased the activation energy of PBT.

scholarly journals Kinetics of anchoring of polymer chains on substrates with chemically active sites

1998 ◽  
Vol 58 (5) ◽  
pp. 6134-6144 ◽  
Author(s):  
G. Oshanin ◽  
S. Nechaev ◽  
A. M. Cazabat ◽  
M. Moreau
Keyword(s):  
Active Sites ◽  
Polymer Chains ◽  
Kinetics Of

Kinetics of polymer chains in elongational flow

1994 ◽  
Vol 172-174 ◽  
pp. 932-934 ◽  
Author(s):  
A.A. Darinskii ◽  
M.G. Saphiannikova
Keyword(s):  
Elongational Flow ◽  
Polymer Chains ◽  
Kinetics Of

scholarly journals In-Depth Analysis of the Effect of Fragmentation on the Crystallization-Driven Self-Assembly Growth Kinetics of 1D Micelles Studied by Seed Trapping

Polymers ◽  
2021 ◽  
Vol 13 (18) ◽  
pp. 3122
Author(s):  
Gerald Guerin ◽  
Paul A. Rupar ◽  
Mitchell A. Winnik
Keyword(s):  
Growth Kinetics ◽  
Self Assembly ◽  
Growth Process ◽  
Elevated Temperatures ◽  
Polymer Chains ◽  
Exponential Law ◽  
Depth Analysis ◽  
Protein Fibrils ◽  
Polymer Fractionation ◽  
Kinetics Of

Studying the growth of 1D structures formed by the self-assembly of crystalline-coil block copolymers in solution at elevated temperatures is a challenging task. Like most 1D fibril structures, they fragment and dissolve when the solution is heated, creating a mixture of surviving crystallites and free polymer chains. However, unlike protein fibrils, no new nuclei are formed upon cooling and only the surviving crystallites regrow. Here, we report how trapping these crystallites at elevated temperatures allowed us to study their growth kinetics at different annealing times and for different amounts of unimer added. We developed a model describing the growth kinetics of these crystallites that accounts for fragmentation accompanying the 1D growth process. We show that the growth kinetics follow a stretched exponential law that may be due to polymer fractionation. In addition, by evaluating the micelle growth rate as a function of the concentration of unimer present in solution, we could conclude that the micelle growth occurred in the mononucleation regime.

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