Morphological Variation of an LB Film of Giant Amphiphiles Composed of Poly(ethylene oxide) and Hydrophobically Modified POSS

Abstract

Hydrophobically modified polyhedral oligomeric silsesquioxanes (XPOSS) are linked to one end of water-soluble poly(ethylene oxide) (PEO) to synthesize giant amphiphiles (XPOSS-PEO). XPOSS-PEO exhibit an interesting surface activation capacity owing to the synergy of the soft PEO segment and hydrophobic XPOSS when they are spread on the water surface and compressed by the barrier. The monolayers of XPOSS-PEO at the air− water interface are transferred onto the silicon substrate at different surface pressures using the Langmuir−Blodgett (LB) film deposition protocol. The modification of the POSS head significantly changes the crystallinity of the PEO tail, which affects the LB film morphologies of the giant amphiphiles. When the POSS are modified with fluorinated agents, the assembled LB films show a fractal growth pattern, but when the POSS are decorated with a pure alkane chain, the fractal growth pattern does not present in the resulting LB film.

Interfacial Behaviors of Giant Amphiphilic Molecules Composed of Hydrophobic Isobutyl POSS and Hydrophilic POSS Bearing Carboxylic Acid Groups at the Air–Water Interface

“…In the past decade, giant amphiphilic molecules have attracted increasing attention. , Giant amphiphilic molecules can self-assemble into nanovesicles, micelles, nanofilaments, and different microphase structures which endow them with promising potential applications in drug delivery and nanotechnology. − In particular, polyhedral oligomeric silsesquioxane (POSS) nanoparticles are frequently used to prepare giant amphiphilic molecules due to their rigid three-dimensional configuration and precise chemical structure. − The POSS nanoparticle with a precise size has no chain entanglement, which allows the giant molecules to show faster assembly kinetics and relaxation behavior than traditional polymers. − Driven by the advances in chemical synthesis tools, giant molecules with entirely rigid nanoparticles and precisely defined sequence have been obtained. − These giant molecules exhibit many interesting assembly behaviors and structures in bulk and solution states. − Despite this progress, the assembly behavior of giant amphiphilic molecules in two-dimensional space is still not well understood.…”

Solution Self-Assembly of Amphiphilic Tadpole-like Giant Molecules Constructed by Monotethering Diblock Copolymer Chain onto a Nanoparticle

“…With the rapid development of click chemistry in the latest decade, various TGMs, as well as other types of intriguing giant molecules, have been able to be precisely and efficiently synthesized in experiments in large quantities, which greatly boosted the studies on the self-assembly behavior of the TGMs. − ,,− Yu et al studied the solution self-assembly behavior of an amphiphilic TGM constructed by tethering one hydrophobic polystyrene (PS) chain onto a polyhedral oligomeric silsesquioxane (POSS) NP. An unexpected phenomenon was found during the micellar morphological changes of sphere → cylinder → vesicle, that is, the radii of the hydrophobic PS core were found to be increased via the sequence of R sphere > R cylinder > R vesicle , which is contrary to the case found in the traditional amphiphilic polystyrene- b -poly­(acrylic acid) diblock copolymer system .…”

Interfacial Behavior of Giant Amphiphiles Composed of Azobenzene and Polyhedral Oligomeric Silsesquioxane

“…Giant molecules synthesized by stepwise linking of molecular nanounits, such as POSS, fullerene, and polyoxometalate (POM), show large size in contrast to small molecules and precise molecular structures compared with polymers and have drawn considerable attention in recent years. − Amphiphilic giant molecules exhibit interesting assembly behaviors in bulk, solution, and interfaces due to their schizophrenic molecular structure, precise size, and no entanglement of molecular nanounits. − Using azobenzene as a building unit with molecular nanounits to construct giant molecules will form a reservoir for multifunctionality design. Recently, azobenzene units are linked to eight vertexes of POSS to form star-like giant molecules, which show both photoresponsive and interesting liquid crystal behaviors. − Nevertheless, there are many other linkage modes of azobenzene and POSS to form giant molecules, especially giant amphiphiles, which are a big blank area for exploration. − …”