Formation of Size‐Controllable Tetragonal Nanoprisms by Crystallization‐Directed Ionic Self‐Assembly of Anionic Porphyrin and PEO‐Containing Triblock Cationic Copolymer

Abstract

The creation of anisotropic nanostructures with precise size control is desirable for new properties and functions, but it is challenging for ionic self‐assembly (ISA) because of the non‐directional electrostatic interactions. Herein, the formation of size‐controllable tetragonal nanoprisms is reported via crystallization‐directed ionic self‐assembly (CDISA) through evaporating a micellar solution on solid substrates. First, ISA is designed with a crystalline polyethylene oxide (PEO) containing cationic polymer poly(2‐(2‐guanidinoethoxy)ethyl methacrylate)‐b‐poly(ethyleneoxide)‐b‐poly(2‐(2‐guanidinoethoxy)‐ethylmethacrylate) (PGn‐PEO230‐PGn) and an anionic 5,10,15,20‐Tetrakis(4‐sulfonatophenyl) porphyrin (TPPS) to form micelles in aqueous solution. The PG segments binds excessive TPPS with amplenet chargeto form hydrophilic corona, while the PEO segments are unprecedentedly dehydrated and tightly packed into cores. Upon naturally drying the micellar solution on a silicon wafer, PEO crystallizationdirects the micelles to aggregate into square nanoplates, which are further connected to nanoprisms. Length and width of the nanoprisms can be facilely tuned by varying the initial concentration. In this hierarchical process, the aqueous self‐assembly is prerequisite and the water evaporation rate is crucial for the formation of nanostructures, which provides multiple factors for morphology regulating. Such precise size‐control strategy is highly expected to provide a new vision for the design of advanced materials with size controllable anisotropic nanostructures.

Thermo/Light Dual-Responsive Helical Dendronized Poly(phenylacetylene)s

“…As documented in the literature, nanocubes through assembly from (co)­polymers are rarely observed due to the thermodynamic favorability of formation of spherical objects . Normally, nanocubes are formed from micelles on interfaces through evaporation-induced aggregation. − However, by manipulating the solvation difference between various structural segments through thermal dehydration or lipophilic interactions, nanocubes are also formed in aqueous media. Therefore, assemblies of these dendronized copolymers should be modulated by interactions among different structural segments.…”