One-dimensional patchy nanostructures are interesting materials due to their excellent interfacial activity and their potential use as carrier for functional nanoparticles. Up to now only wormlike crystalline-core micelles (wCCMs) with a nonfunctional patchy PS/PMMA corona were accessible using crystallization-driven self-assembly (CDSA) of polystyrene-block-polyethylene-block-poly(methyl methacrylate) (SEM) triblock terpolymers. Here, we present a facile approach toward functional, patchy wCCMs, bearing tertiary amino groups in one of the surface patches. The corona forming PMMA block of a SEM triblock terpolymer was functionalized by amidation with different N,N-dialkylethylenediamines in a polymer analogous fashion. The CDSA of the functionalized triblock terpolymers in THF was found to strongly depend on the polarity/solubility of the amidated PMMA block. The lower the polarity of the amidated PMMA block (increased solubility), the higher is the accessible degree of functionalization upon which defined, well-dispersed wCCMs are formed. Interestingly, also the structure of the patchy corona can be tuned by the composition/chemistry of the functional patch, giving rise to spherical patches for R = methyl, ethyl and rectangular patches for R = isopropyl. Patchy wCCMs were successfully used as template for the selective incorporation of Au nanoparticles within the amidated corona patches, showing their potential as versatile platform for the construction of functional, mesostructured hybrid materials.
Heterogeneous catalysis with supported nanoparticles (NPs) is a highly active field of research. However, the efficient stabilization of NPs without deteriorating their catalytic activity is challenging. By combining top-down (coaxial electrospinning) and bottom-up (crystallization-driven self-assembly) approaches, we prepared patchy nonwovens with functional, nanometer-sized patches on the surface. These patches can selectively bind and efficiently stabilize gold nanoparticles (AuNPs). The use of these AuNP-loaded patchy nonwovens in the alcoholysis of dimethylphenylsilane led to full conversion under comparably mild conditions and in short reaction times. The absence of gold leaching or a slowing down of the reaction even after ten subsequent cycles manifests the excellent reusability of this catalyst system. The flexibility of the presented approach allows for easy transfer to other nonwoven supports and catalytically active NPs, which promises broad applicability.
Block copolymer self-assembly in solution paves the way for the construction of well-defined compartmentalized nanostructures. These are excellent templates for the incorporation and stabilisation of nanoparticles (NPs), giving rise to highly relevant applications in the field of catalysis or sensing. However, the regio-selective incorporation of NPs in specific compartments is still an issue, especially concerning the loading with different NP types. Using crystallisation-driven self-assembly (CDSA), functional worm-like crystalline-core micelles (wCCMs) with a tailor-made, nanometre-sized patchy corona were prepared as versatile templates for the incorporation and stabilisation of metal and metal oxide NPs. Different strategies, like ligand exchange or co-precipitation of polymer stabilised NPs with one surface patch, were developed that allow the incorporation of NPs in specific regions of the patchy wCCM corona. Independent of the NP type and the incorporation method, the NPs showed no tendency for agglomeration and were fixed within the corona patches of the wCCMs. The binary loading of patchy micelles with metal and metal oxide NPs was realised by combining different loading strategies, yielding hybrids with homogeneously dispersed NPs guided by the patchy structure of the template.
Surface-modified carbon nanotubes (CNTs) have become well-established filler materials for polymer nanocomposites. However, in immiscible polymer blends, the CNT-coating is selective toward the more compatible phase, which suppresses their homogeneous distribution and limits harnessing the full potential of the filler. In this study, we show that multiwalled CNTs with a patchy polystyrene/poly(methyl methacrylate) (PS/PMMA) corona disperse equally well in both phases of an incompatible PS/PMMA polymer blend. Unlike polymer-grafted CNTs with a uniform corona, the patchy CNTs are able to adjust their corona structure to the blend phases by selective swelling/collapse of respective miscible/immiscible surface patches. Importantly, the high interfacial activity of patchy CNTs further causes a significant decrease in PMMA droplet size with increasing filler content. The combined effect of compatibilization and homogeneous distribution makes patchy CNTs interesting materials for polymer blend nanocomposites, where next to the compatibilization, a homogeneous filler distribution is important to gain the desired materials property (e.g., reinforcement).
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