Uniform 1D Micelles and Patchy & Block Comicelles via Scalable, One-Step Crystallization-Driven Block Copolymer Self-Assembly

Abstract

Fiber-like (1D) core-crystalline micelles of uniform length can be obtained in protocols involving multiple steps from block copolymers (BCPs) in which crystallization of the core-forming polymer drives the self-assembly. Here we report a systematic study that shows that adding small amounts (<5 w/w%) of a homopolymer corresponding to the core-forming block of the BCP enables uniform 1D micelles (mean lengths L n = 0.6 to 9.7 μm) to be obtained in a single step, simply by heating the mixture in a selective solvent followed by slow cooling. A series of poly­(ferrocenyldimethylsilane) (PFS) BCPs with different corona-forming blocks and different compositions as well as PFS homopolymers of different lengths were examined. Dye labeling and confocal fluorescence microscopy showed that the homopolymer ends up in the center of the micelle, signaling that it served as the initial seed for epitaxial micelle growth. The rate of unimer addition was strongly enhanced by the length of the PFS block, and this enabled more complex structures to be formed in one-pot self-assembly experiments from mixtures of two or three BCPs with different PFS block lengths. Furthermore, BCP mixtures that included PFS-b-PI (PI = polyisoprene) and PFS-b-PDMS with similar PFS block lengths resulted in simultaneous addition to growing micelles, resulting in a patchy block that could be visualized by staining the vinyl groups of the PI with Pt nanoparticles. This approach also enabled scale up, so that uniform 1D micelles of controlled architecture can be obtained at concentrations of 10 w/w % solids or more.

Sorafenib Nanomicelles Effectively Shrink Tumors by Vaginal Administration for Preoperative Chemotherapy of Cervical Cancer

“…The micelles with particle size less than 30 nm were formed by self-assembly of amphiphilic properties, while the particle size in this study was larger than 50 nm. Considering that SF micelles were prepared using probe ultrasound, it has been reported that ultrasound can break the micelles into smaller micelles fragments and use these fragments as nuclei to promote micelle growth and finally obtain homogeneous micelles [55]. Therefore, SF micelles may be formed by a "micelle aggregation" [56], which aggregated from small simple micelles to form large complex micelles.…”

Block Copolymers with Crystallizable Blocks: Synthesis, Self-Assembly and Applications

“…If T a is increased well above the T c of both diblock copolymers, again the growth kinetics determine the final observable corona arrangement-i.e., for similar growth rates, a patchy segmentation is generated (Figure 8e). This concept can also be transferred to mixtures of PFS homopolymers and PFS-based BCPs [146]. Due to the higher T c of the PFS homopolymer, a certain fraction of PFS homopolymer crystal fragments will survive upon proper choice of T a ; these fragments then act as seeds upon subsequent cooling and annealing.…”

Patchy Micelles with a Crystalline Core: Self-Assembly Concepts, Properties, and Applications

“…If T a is increased well above the T c of both diblock copolymers, again the growth kinetics determine the final observable corona arrangement—i.e., for similar growth rates, a patchy segmentation is generated ( Figure 8 e). This concept can also be transferred to mixtures of PFS homopolymers and PFS-based BCPs [ 146 ]. Due to the higher T c of the PFS homopolymer, a certain fraction of PFS homopolymer crystal fragments will survive upon proper choice of T a ; these fragments then act as seeds upon subsequent cooling and annealing.…”

“…Furthermore, NP hybrid materials with block co-micelles derived from co-assembly of diblock copolymers were reported. Here, the spatially confined incorporation of platinum NPs and CdSe quantum dots was enabled by selective interactions with functional corona patches [ 146 , 178 ].…”