Process Development for Rapid Self-Assembly of PPV-b-PMMA Block Copolymer
Date Issued
2016
Date
2016
Author(s)
Kao, Ting-Chung
Abstract
Rod-coil block copolymers have long been a research interest for their great potentials in nanolithography and flexible optoelectronics applications. By adjusting interactions between segments and their volume fractions, one can acquire various nanoscale morphologies. However, the segment interactions of rod-rod and rod-coil of the copolymers are very strong, the formation of ordered structure is rather difficult even they are annealed under a fairly high temperature for a long time. To promote the formation of ordered structure of rod-coil block copolymer, chemical modifications of side chain or main chain are usually used to suppress interactions, but that affects the original physical properties of pristine copolymers. In this work, we’ve developed a facile method to form a highly ordered nanostructure of PPV-b-PMMA at low temperature and short time without any chemical modification. By adding high boiling point selective additives in the copolymer, the thermodynamic equilibrium of ordered structure can be reached with relatively low temperature and short time. If the high boiling point additive cannot remove during the annealing process completely that will affect the chemical and physical properties of the copolymer. Therefore, we further improve the process by treating the samples under different annealing environment. Two new systems are investigated: open system and vacuum system as compared with the original confined system (sample annealed in a metal washer). The additive has more room to facilitate the movement of copolymer and to be evaporated effectively during the annealing. By optimizing the annealing condition, we can not only retain the nanostructure of the copolymer, but also improve the quality of ordered structure without presence of any additive. For example, vaccum system can help copolymer to form structure in 1.5hr annealing period. This technique provides an efficient and energy-saving process for self-assembly copolymers to form highly ordered structures.
Subjects
block copolymers
rod – coil
self-assembly
additive
thermal annealing
open system
vacuum system
Type
thesis
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