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.
Self-assembly of block copolymers (BCPs) in three-dimensional (3D) confinement of emulsion droplets has emerged as a versatile route for the formation of functional micro- and nanoparticles. While the self-assembly of amorphous coil–coil BCPs is fairly well documented, less is known about the behavior of crystalline–coil BCPs. Here, we demonstrate that confining a linear ABC triblock terpolymer with a crystallizable middle block in oil-in-water (O/W) emulsions results in a range of microparticles with frustrated inner structure originating from the conflict between crystallization and curved interfaces. Polystyrene-block-polyethylene-block-poly(methyl methacrylate) (PS-b-PE-b-PMMA, S32E36M32 93) in toluene droplets was subjected to different preparation protocols. If evaporation was performed well above the bulk crystallization temperature of the PE block (T evap > T c), S32E36M32 93 first microphase-separated into microparticles with lamella morphology followed by crystallization into a variety of frustrated morphologies (e.g., bud-like, double staircase, spherocone). By evaporating at significantly lower temperatures that allow the PE block to crystallize from solution (T evap < T c), S32E36M32 93 underwent crystallization-driven self-assembly into patchy crystalline-core micelles, followed by confinement assembly into lenticular microparticles with compartmentalized hexagonal cylinder lattices. The frequency of these frustrated morphologies depends on polymer concentration and the evaporation protocol. These results provide a preliminary understanding of the morphological behavior of semicrystalline block copolymers in 3D soft confinement and may provide alternative routes to structure multicompartment microparticles from a broader range of polymer properties.
Multiresponsive polymers that can respondt o severale xternals timulia re promising materialsf or am anifold of applications. Herein, af acile method for the synthesis of triple-responsive (pH, temperature, CO 2 ) poly(N,N-diethylaminoethyl methacrylamide) by ap ostpolymerizationa midation of poly(methyl methacrylate) (PMMA)i sp resented. Combined with trivalent counterions ([Fe(CN) 6 ] 3À )b oth an upper and lower criticals olution temperature (UCST/LCST)-type phase behaviorc an be realized at pH 8a nd 9. PMMA and PMMA-based blockc opolymers are readily accessible by living anionic and controlled radicalp olymerization techniques, whicho pens access to various responsive polymer architectures based on the developed functionalization method. This method can also be applied on melt-processed bulk PMMA samples to introduce functional, responsive moieties at the PMMA surface.Stimuli-responsiveo r" smart" polymers, which can change their physicochemical properties (e.g.,s olubility) upon applyinga n externals timulus (pH, temperature, light, magnetic fields, CO 2 , etc.), are highly attractivea nd intensively studied materialsd ue to the wide range of applications, such as responsive micelles and micro/nano-gels for biomedical applications, switchable membranes and coatings, smarta ctuators, or CO 2 sensing. [1][2][3] The most prominent examples of multi-responsive polymers are basedo nm ethacrylate or acrylamide-type monomers with pendant N,N-dialkylaminog roups (alkyl = methyl, ethyl, iso-[a] C.Figure 3. Ta iloring the thermo-responsive solution behaviorofP DEAE-MAm 1030 (c = 1gL À1 )int he presence of trivalent [Fe(CN) 6 ] 3À counterions. A) UCST-and LCST-typephase transitions in dependence of pH for two different K 3 [Fe(CN) 6 ]c oncentrations( c = 0.5 mm (squares), c = 0.75 mm (circles)) and B) in dependence of K 3 [Fe(CN) 6 ]c oncentration in pH 8b uffer solutions.
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