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Nat Mater. 2017 Jul;16(7):767-774. doi: 10.1038/nmat4891. Epub 2017 Apr 17.

Tuning crystallization pathways through sequence engineering of biomimetic polymers.

Author information

1
Physical Sciences Division, Pacific Northwest National Laboratory, Richland, Washington 99352, USA.
2
School of Chemistry and Molecular Engineering, East China Normal University, Shanghai 200241, China.
3
Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, Livermore, California 94550, USA.
4
Department of Chemical Engineering, University of Washington, Seattle, Washington 98195, USA.
5
Center for Biomaterials and Biopathways, Department of Chemistry, Zhejiang University, Hangzhou, Zhejiang 310027, China.
6
School of Natural Sciences University of California Merced, Merced, California 95343, USA.
7
Department of Materials Science and Engineering, University of Washington, Seattle, Washington 98195, USA.

Abstract

Two-step nucleation pathways in which disordered, amorphous, or dense liquid states precede the appearance of crystalline phases have been reported for a wide range of materials, but the dynamics of such pathways are poorly understood. Moreover, whether these pathways are general features of crystallizing systems or a consequence of system-specific structural details that select for direct versus two-step processes is unknown. Using atomic force microscopy to directly observe crystallization of sequence-defined polymers, we show that crystallization pathways are indeed sequence dependent. When a short hydrophobic region is added to a sequence that directly forms crystalline particles, crystallization instead follows a two-step pathway that begins with the creation of disordered clusters of 10-20 molecules and is characterized by highly non-linear crystallization kinetics in which clusters transform into ordered structures that then enter the growth phase. The results shed new light on non-classical crystallization mechanisms and have implications for the design of self-assembling polymer systems.

PMID:
28414316
DOI:
10.1038/nmat4891
[Indexed for MEDLINE]

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