Alexandria Digital Research Library

Defectivity in Laterally Confined Lamella-Forming Diblock Copolymers: Thermodynamic and Kinetic Aspects

Author:
Takahashi, Hassei
Degree Grantor:
University of California, Santa Barbara.Chemical Engineering
Degree Supervisor:
Fredrickson Glenn H
Place of Publication:
[Santa Barbara, Calif.]
Publisher:
University of California, Santa Barbara
Creation Date:
2012
Issued Date:
2012
Topics:
Chemical engineering, Physics, and Materials Science
Keywords:
Self-consistent field theory (SCFT)
Block copolymer lithography
Surface patterning
String method
Directed-self assembly
Description:

We use self-consistent field theory (SCFT) to study the directed self-assembly of laterally confined diblock copolymers. We focus on systems where the self-assembled lamellae are oriented parallel to the selective sidewalls of the channel. While well-ordered, perfect lamellae are observed in narrow channels both experimentally and numerically, undesirable defective structures also emerge. We therefore investigate the energetics of two isolated defects, dislocations and disclinations, for various segregation strengths and channel dimensions and establish conditions that favor the formation of defects. We also determine the energy barrier and the transition path between the defective and perfect state using the string method. In the case of transitions from defective to well-ordered states, we found that only a few kT of energy is necessary to overcome the kinetic barrier and suppress the defect, sharply contrasting with the large gain in free energy (many tens of kT) that is necessary for the formation of the defect from the pristine state.

Format:
Text
Collection(s):
UCSB electronic theses and dissertations
ARK:
ark:/13030/m5057gjq
Merritt ARK:
ark:/13030/m5057gjq
Rights:
Inc.icon only.dark In Copyright
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