Hierarchical morphologies, functional properties, and electrospun fibers of supramolecular complexes of diblock copolymer/amphiphile systems: Dissertation

This thesis consists of 5 publications, where morphologies, functional properties, and electrospun fibers of supramolecular diblock copolymer/amphiphile systems are studied. Supramolecular systems consists of polystyrene-block- poly(4-vinylpyridine), its methane sulphonic acid and toluene sulphonic acid salts, and different oligomeric amphiphilic molecules physically bonded to the latter block. In Article I, morphologies of polystyrene-block-poly(4-vinylpyridine) and its methane sulphonic acid salts, and hydrogen bonded pentadecylphenol were investigated at different temperatures. Based on reversibility of the hydrogen bonding and polymer/pentadecylphenol phase behaviour, novel structures and reversible order-order and order-disorder transitions were observed as a function of temperature. In Article II, a block copolyelectrolyte complex based on toluene sulphonic acid salt of polystyrene-block-poly(4- vinylpyridine) hydrogen bonded to pentadecylphenol was investigated. After shear alignment, lamellar-within-cylindrical self-assembly with parallel structures was observed. Anisotropic conductivity of the sample was investigated and observed to be astonishingly small due to residual defects and domain boundaries still found in the sample. In Article III, porous materials were prepared using polystyrene-block-poly(4-vinylpyridine) with coordinated zinc dodecylbenzene sulphonate. Porous lamellar structures with dense set of brushes at the pore interfaces were obtained as the coordination bonding between the amphiphiles and poly(4-vinylpyridine) block was cleaved. Collapse of the structure was prevented probably due to the defects and grain boundaries of the non-aligned glassy matrix. In Article IV, porous mesoscale fibers were prepared by electrospinning polystyrene-block-poly(4-vinylpyridine) with hydrogen bonded pentadecylphenol. This leads to structure formation at three different length scales. The porosity was achieved by cleaving the amphiphiles from the structure by extraction. In Article V, studies of electrospun fibers were continued, and it was shown that the block copolymer level structures can be tuned to some extent even if the structures after the electrospinning are not in the thermal equilibrium. Englanninkieliset avainsanat self-assembly hierarchy physical bonding porosity electrospinning