(690e) Directed Self-Assembly of Acrylic Terpolymers With Mixed Block Regimes

Obtaining the optimal polymer microstructure with the optimal chemical domains for specific applications is difficult. Because of this, there has been much research into how to manipulate the microstructures of self-assembling polymers such that desired chemical functionalities and microstructures can be simultaneously achieved. The specific microstructure formed in a phase-separated system is determined by minimizing the free energy of the polymer chain conformations and the interfacial energy between the two microdomains. To date, the thermodynamics that define the interfacial curvature, and therefore, the microstructure have largely been tuned by changing polymer composition.  Polymers with mixed block regimes offer a relatively new variable for changing the microstructure at a specific composition. For diblock terpolymers, the thermodynamic behavior changes as a third monomer species is copolymerized; differences in self-assembly between the A-b-(B-co-C) architecture, (A-co-C)-b-B architecture, and (A-co-C)-b-(B-co-C) are to be expected. This work explores the differences in these three architectures for an all acrylic system composed of hydroxyethyl acrylate (HEA), methyl acrylate (MA), and octyl acrylate (OA).

Here three diblock architectures, P(HEA)-b-P(OA-co-MA), P(HEA-co-MA)-b-P(OA), and P(HEA-co-MA)-b-P(OA-co-MA) are compared with two triblock architectures, the non-frustrated P(HEA)-b-P(MA)-b-P(OA) and the frustrated P(HEA)-b-P(OA)-b-P(MA). These five architectures were synthesized at four different compositions, where the ratio between the volume fractions HEA and OA remains constant at fHEA/ fOA = 1.74, and the total molecular volume remains constant at approximately 11,600 mL/ mol. The manipulated variable, fMA, was used to explore the effects of altering the enthalpic interaction between polymer blocks. This talk will present results from synchrotron small angle x-ray scattering (SAXS) experiments preformed at Diamond Light Source; the SAXS results characterize the self-assembly of these 20 polymers in the bulk, in water (a selective solvent for HEA), and in THF (a good solvent).