Periodic Reporting for period 1 - cOMPoSe (Optical Metamaterials by Polymer Self-assembly)
Reporting period: 2016-04-01 to 2018-03-31
In the first part of the project we studied a fundamental aspect of polymer physics, the crystallization of polymers within the confinement of the continuous network structure of the gyroid. We demonstrated that crystallization proceeds along the least-convoluted pathways of the tortuous gyroid network of a self-assembled block copolymer. Importantly, this crystallization renders the polymer film birefringent. We could show that this birefringence can be used to identify individual gyroid grains by polarization microscopy despite the morphology being structurally isotropic.
The second part of the project focused on characterizing polymer self-assembly in films of two different gyroid-forming block copolymers during well-controlled annealing experiments by means of in situ x-ray scattering. These scattering experiments revealed the effects of several key annealing parameters on the morphology, degree of order, and orientation of the gyroid in block copolymer films. This allowed identifying protocols for the reproducible generation of gyroid polymer films with controlled orientation and well-ordered structures in three dimensions. These gyroid polymer films were used as templates for the fabrication of optical metamaterials by replication of the continuous network structure into gold in the third part of the project. The resulting gyroid metamaterials exhibited a depressed plasma frequency as well as circular and linear dichroism, which were found to be sensitive to the orientation of the gyroid and its surface terminations.