Hierarchical self-assembly from nanometric micelles to colloidal spherical superstructures

POLYMER

卷:126

Article

Bertula, Kia¹  Nonappa^1,2  Myllymaki, Teemu T. T.¹  Yang, Hongjun³  Zhu, X. X.³  Ikkala, Olli^1,2 

[1] Aalto Univ, Sch Sci, Dept Appl Phys, Mol Mat Grp, POB 15100, FI-00076 Espoo, Finland

[2] Aalto Univ, Sch Chem Engn, Dept Bioprod & Biosyst, POB 11000, FI-00076 Espoo, Finland

[3] Univ Montreal, Dept Chem, CP 6128,Succursale Ctr Ville, Montreal, PQ H3C 3J7, Canada

关键词: Self-assembly;    Hydrogen bonding;    Micelles;    Supermicelles;    Electron tomography;   

DOI  :  10.1016/j.polymer.2017.08.027

来源: Elsevier

【 摘 要 】

We report sequential self-assembly of low molecular weight asymmetric star-like polymers from nanometric spherical micelles (core diameter 8-12 nm) to colloidal spherical superstructures (d > 500 - 1000 nm) in aqueous media, as directed by quadruple hydrogen bonding moieties activated by solvent exchanges. The molecules consist of a rigid asymmetric steroidal cholic acid (CA) core, whose hydroxyl groups are first grafted with four oligomeric allyl glycidyl ether (AGE) chains involving six repeat units. The allylic double bonds are thiol-clicked with cysteamine (HS-(CH2)(2)-NH2), and in the final step their amino end groups are conjugated with 2-ureido-4[1H]-pyrimidinone (UPy) via isocyanate chemistry using UPy-(CH2)6-NCO to obtain asymmetric star-like facially amphiphilic molecules denoted as CA[(AGE-NH2)(6)](4)-(UPy)(n). They self -assemble into spherical micelles in dimethyl sulfoxide (DMSO), which suppresses the dimerization of UPys. Solvent exchange from DMSO to water activates the inter-micellar hydrogen bonds via the peripheral UPy units, which triggers the formation of spherical submicron to micron scale superstructures. Based on three-dimensional (3D) reconstruction using transmission electron tomography (ET), we show that such structures are composed of densely packed micellar network. Our work shows that surfactant -like molecules, characteristically leading to micelles, can undergo complex and hierarchical self -assembly to microscale by equipping the solubilising chains with hydrogen bonding units that can be switched ON and OFF by sequential solvent exchanges. (C) 2017 Elsevier Ltd. All rights reserved.

【 授权许可】

Free