Horizontally and Vertically Aligned Polymeric Nanosheets:CO2-Induced Morphological Changes of Block Copolymer Thin Films
writer：Hideaki Yokoyama*, Lei Li, Cedric Dutriez, Yuko Iw
keywords：SUPERCRITICAL CARBON-DIOXIDE; POLYSTYRENE; CO2; NANOTECHNOLOGY; TEMPERATURE; TRANSITION; TEMPLATES; MONOLITHS
source：期刊
Recently, the carbon dioxide (CO2) Process with sphere forming block copolymer (bcp) templates successfully introduced nanometer cells into polymeric materials. CO2 selectively swells CO2-philic domains of fluorinated blocks and introduces nanometer voids in the CO2-philic domains. We extended the same methodology to bcp templates with nonspherical domains. Depending on the initial morphologies controlled by selectivity of casting solvents, vertically or horizontally aligned polymer nanosheets spontaneously appeared after the CO2 process and were confirmed by scanning electron microscopy and grazing incident small-angle X-ray scattering. Selective swelling of minority domains with CO2 induces transition to lamellar morphology during the process and results in stacking sheet structure after depressurization of CO2.