Poly(N-isopropylacrylamide) Films at the Air-Water Interface

Abstract

PolyUV-isopropylacrylamide) (poly(NIPAM)) film spread at the air-water interface from its aqueous solution has been investigated by surface pressure and ellipsometric measurements at two temperatures (16.0 and 31.3 °C). The surface pressure steeply increased at low real spread concentration of poly(NIPAM), and it more gradually attained a plateau one at high temperature. The plateau surface pressure at 16.0 °C was lower than that at 31.3 °C. The amount of polymer adsorbed at the air-water interface was determined by ellipsometry, and its plateau adsorbed amount at 31.3 °C was twice as large as that at 16.0 °C, whereas the thickness of the adsorbed layer at 16.0 °C was larger than that at 31.3 °C. Such an adsorption behavior at the air-water interface was strongly related to the transition of poly(NIPAM) from a hydrophilic to a hydrophobic structure in bulk solution. Moreover, it was found that some portions of the spread polymer were desorbed from the interface and the magnitude of the adsorbed amount was similar to that on the silica surfaces.

The kinetics of the alkaline degradation of daptomycin

“…The experiment was performed using a solution surface of 137 cm 2 and at constant temperature (20.0°C). A sandblasted platinum plate was attached to an electrobalance, and the stage was slowly moved up until the edge of the plate touched the solution surface 7. The tensiometer accuracy was determined by comparing the surface tension of pure water (typically 71.4 mN/m at 20.0°C) to its reference value (72.75 mN/m) 8.…”

A novel route to prepare highly surface active nanogel particles based on nonaqueous emulsion polymerization

“…It is expected that the solid particles based on poly( N ‐isopropylacrylamide) (PNIPAM) will be a promising candidate as an emulsifier for nonaqueous emulsions. The PNIPAM possesses an amphiphilic nature because it has both amide groups and isopropyl groups, making it surface active . It is widely recognized that amphiphilic block copolymers consisting of a PNIPAM segment and a hydrophobic segment can form a core–shell micellar structure .…”

Cross‐Linking Density and Temperature Effects on the Self‐Assembly of SiO2—PNIPAAm Core–Shell Particles at Interfaces

“…37 PNIPAAm displays a dramatic change in particle size and hydrophobicity the temperature is increased above the LCST (ca. 32 °C) 38–40. By using a thermoresponsive core–shell particle, thermosensitive Pickering stabilization could be investigated.…”

“…32 8C). [38][39][40] By using a thermoresponsive core-shell particle, thermosensitive Pickering stabilization could be investigated. While conventionally this is done by determining the equilibrium interfacial tension at various temperatures, we also used the dynamic character of the surface stabilization and determined the properties with respect to different heating rates, thereby determining how responsive the PNIPAAm-based particles adsorbed at the interface were.…”