作者：Zhixiu Dong, Gangyao Wen*, Martha Kafetzi, Stergios Pispas, Qi Zhang
關(guān)鍵字：LB film; double hydrophilic block copolymer; Langmuir monolayer; network structure; subphase condition
論文來源：期刊
具體來源：The Journal of Physical Chemistry B 2025, DOI: 10.1021/acs.jpcb.5c02102
發(fā)表時(shí)間：2025年
The detailed micelle/aggregate structures of double hydrophilic diblock copolymers (DHBCs) at the air/water interface are not well understood and need to be further explored. The Langmuir film balance technique and atomic force microscopy were used to study the effects of subphase pH and temperature on the interfacial aggregation behavior of one DHBC of poly[2-(dimethylamino)ethyl methacrylate]-b-poly[oligo(ethylene glycol) methyl ether methacrylate] (PDMAEMA-b-POEGMA) and the structures of its Langmuir-Blodgett (LB) films, respectively. At the air/water interface, the PDMAEMA-b-POEGMA copolymer forms a dense network structure of circular micelles with the hydrophobic carbon backbones of PDMAEMA and POEGMA blocks as the tiny cores and their hydrophilic side chains as the short shells, and each copolymer molecule forms two connected micelles/cores. This ultrafine core-shell micelle structure is successfully identified by using our newly proposed relative aggregation number method, which is different from the isolated core-shell-petal and core-shell-corona structures presented in our previous DHBC systems. With the increase of subphase pH, the isotherms of the copolymer first move towards smaller mean molecular areas (mmA) and then move towards larger ones. Under alkaline conditions, the monolayer exhibits the largest hysteresis degree, whereas that under neutral conditions exhibits the smallest one. As temperature rises, the isotherms under acidic conditions move to larger mmA due to the increased thermal mobility of OEGMA side chains. Under neutral and alkaline conditions, the isotherms at 20 oC appear at the left of those at 10 oC due to the collapse of OEGMA side chains above 15 oC.
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