Letter Cite This: ACS Macro Lett. 2019, 8, 955−961
pubs.acs.org/macroletters
Seeded Photoinitiated Polymerization-Induced Self-Assembly: Cylindrical Micelles with Patchy Structures Prepared via the Chain Extension of a Third Block Xiaocong Dai,† Yuxuan Zhang,† Liangliang Yu,† Xueliang Li,† Li Zhang,†,‡ and Jianbo Tan*,†,‡ †
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Department of Polymeric Materials and Engineering, School of Materials and Energy, Guangdong University of Technology, Guangzhou 510006, China ‡ Guangdong Provincial Key Laboratory of Functional Soft Condensed Matter, Guangzhou 510006, China S Supporting Information *
ABSTRACT: Cylindrical micelles formed by the self-assembly of block copolymers are of interest for a wide range of applications. In this study, aqueous seeded photoinitiated polymerization-induced self-assembly (photo-PISA) is developed for the preparation of cylindrical block copolymer micelles with patchy structures at high solids contents. Cross-linked cylindrical block copolymer micelles prepared by photo-PISA are used as seeds for further chain extension. Surface roughness of the patchy cylindrical block copolymer micelles can be controlled by varying degree of polymerization (DP) of the third block. The obtained patchy cylindrical micelles can be further functionalized via the modification of the third block. Due to the high solids content of patchy cylindrical micelles prepared by seeded photo-PISA (10% w/w or higher), we expect that this study will greatly expand the promise of PISA for the large-scale preparation of cylindrical micelles with well-defined structures.
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comicelles can also be prepared by adding a different unimer into a solution of crystallite seed micelles. However, it is inevitable that a crystallizable core-forming block is required to fulfill the requirement of CDSA. Over the past ten years or so, the invention of polymerization-induced self-assembly (PISA) mediated by reversible addition−fragmentation transfer (RAFT) polymerization allows the creation of cylindrical block copolymer micelles at high solids contents (up to 50%) in either aqueous or organic media.15−23 In a typical PISA formulation, a macromolecular chain transfer agent (macro-CTA) is chain extended in a selective solvent that contains a second monomer. As the polymerization proceeds, the core-forming block of the diblock copolymer becomes insoluble in the selective solvent, leading to the occurrence of in situ self-assembly. Similar to the solution self-assembly of block copolymers, the window for the preparation of pure cylindrical block copolymer micelles by PISA is still very narrow.24−26 Due to the high concentrations of cylindrical block copolymer micelles prepared in PISA, freestanding physical gel is typically formed at room temper-
ylindrical block copolymer micelles have attracted extensive attention due to their unique geometry with a high aspect ratio as well as their ability to introduce functional groups to the surface.1,2 As a result of the large surface areas and anisotropic structures, cylindrical block copolymer micelles have found use in different areas, including hydrogels,3 Pickering emulsion,4 molecule separation,5 superflocculants,6 and organic photovoltaic devices.7 Cylindrical block copolymer micelles are typically prepared by solution self-assembly of block copolymers that involves the synthesis of amphiphilic block copolymers and the selfassembly of block copolymers in a selective solvent.8 However, this method often leads to very low block copolymer concentrations (
