Room temperature crystallization of amorphous polysiloxane using photodimerization

Bulk crystallization in flexible polymeric systems is difficult to control due to the random orientation of the chains. Here we report a photo cross-linking strategy that results in simultaneous cross-linking and crystallization of polysiloxane chains into millimeter sized leaf-like polycrystalline...

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Bibliographic Details
Published in:Chemical science (Cambridge) 2020-02, Vol.11 (11), p.381-388
Main Authors: Wright, Taylor, Petel, Yael, Zellman, Carson O, Sauvé, Ethan R, Hudson, Zachary M, Michal, Carl A, Wolf, Michael O
Format: Article
Language:English
Subjects:
Anthracene
Atomic force microscopy
Chemistry
Crosslinking
Crystal growth
Crystallization
Microscopy
Morphology
NMR
Nuclear magnetic resonance
Nucleation
Optical microscopy
Room temperature
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Summary:Bulk crystallization in flexible polymeric systems is difficult to control due to the random orientation of the chains. Here we report a photo cross-linking strategy that results in simultaneous cross-linking and crystallization of polysiloxane chains into millimeter sized leaf-like polycrystalline structures. Polymers containing pendant anthracene groups are prepared and undergo [4+4] photocycloaddition under 365 nm irradiation at room temperature. The growth and morphology of the crystalline structures is studied using polarized optical microscopy (POM) and atomic force microscopy and is found to progress through three unique stages of nucleation, growth, and constriction. The mobility of the individual chains is probed using pulsed-field gradient (PFG) NMR to provide insights into the diffusion processes that may govern chain transport to the growing crystal fronts. The room temperature crystallization of this conventionally amorphous polymer system may allow for a new level of morphological control for silicone materials. Millimeter sized polymer crystallites grow rapidly when anthracene-containing siloxanes are photocrosslinked using UV light.
ISSN:2041-6520
2041-6539
DOI:10.1039/c9sc06235a