Master Thesis Defense by Anders Bakke – Niels Bohr Institute - University of Copenhagen

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Master Thesis Defense by Anders Bakke

An X-Ray Scattering Study of Novel Diblock Copolymers and DPD Simulation Study of Polymer Stars

This thesis aims to investigate a novel diblock copolymer using X-ray scattering and the application of dissipative particle dynamics simulations on polymers with a star architecture.

The first part is based on small-angle X-ray scattering experiments on a novel organometallic diblock copolymer; poly(isoprene)-\textit{b}-poly(ferrocenyl-methyl methacrylate) of different molecular volumes and compositions. The aim is to examine whether or not the polymer exhibit well-ordered structure in the bulk and to determine the Flory-Huggins interaction parameter between the blocks. The structure of the diblock copolymer was determined by evaluating the relative distance between observed peaks in the scattering data, and the Flory-Huggins interaction parameter was estimated using Random Phase Approximation theory.

The second part is a study of the application of using dissipative particle dynamics simulations to predict the morphological structure of polymer stars modeled using a diblock approximation approach. The simulations have been performed to reflect a known sample; poly(isoprene)-poly(styrene)-poly(2-vinylpyridine), mapping a large parameter space of various strength of interaction between the first and third arm and of increasing length of the third arm.

The structures of the diblock copolymers samples was estimated and agreed with our predictions from the general phase behavior of diblock copolymers known from literature. The Flory-Huggins interaction parameters was successfully determined from the Random Phase Approximation model, in addition to the average statistical segment length of the blocks, where we obtained values comparable to previous research. Obtained morphologies of the simulated polymer stars partly agrees with performed small-angle X-ray scattering measurements and with previous research, though our diblock approach seems to generally underestimate the block-block interactions.