What selects lamellar thickness in polymer crystals? · revision history

Revision 2

Accepted · core change · record

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Title · changed
Revision 1: What selects lamellar thickness in polymer crystals
Revision 2: What selects lamellar thickness in polymer crystals?
Plain
When long polymers crystallize they fold back and forth into thin plates called lamellae, about 100 Angstrom thick. Which process fixes this thickness and the growth speed is disputed among competing theories.
Precise · changed · core
Revision 1: Flexible polymers crystallizing from melt or solution form chain-folded lamellae of thickness l around $1e-6\,\mathrm{cm}$, with $\ell \sim 1 / (T_m^{0} - T_c)$, where $T_m^{0}$ is the equilibrium melting temperature and $T_c$ the crystallization temperature. Lauritzen-Hoffman secondary nucleation, Sadler-Gilmer rough-surface growth and Strobl's mesomorphic-intermediate model give different mechanisms. Determine which mechanism selects l and the growth rate $G(T_c)$, by direct observation of the growth front in simulations of realistic chains or in situ scattering and microscopy.
Revision 2: Flexible polymers crystallizing from melt or solution form chain-folded lamellae of thickness l around $10^{-6}\,\mathrm{cm}$, with $\ell \sim 1 / (T_m^{0} - T_c)$, where $T_m^{0}$ is the equilibrium melting temperature and $T_c$ the crystallization temperature. Lauritzen-Hoffman secondary nucleation, Sadler-Gilmer rough-surface growth and Strobl's mesomorphic-intermediate model give different mechanisms. Determine which mechanism selects l and the growth rate $G(T_c)$, by direct observation of the growth front in simulations of realistic chains or in situ scattering and microscopy.
Settled by
Molecular-resolution observation of the growth front that identifies the rate-limiting step and reproduces $l(T_c)$ and $G(T_c)$ for a specific polymer.
Kind
phenomenon
Answer type
mechanism
References
(empty)
Literature status
contested
Status note
(empty)
Posed since
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Decisions