Influence of microgel packing on raspberry-like heteroaggregate assembly

Abstract

We describe the influence of microgel packing on colloidal-phase mediated heteroaggregation using poly(N-isopropylacrylamide) and poly(N-isopropylmethacrylamide) microgels with 1% mol or 5% mol N,N'-methylenebis(acrylamide) cross-linker. This system is uniquely designed to interrogate the influence of microgel structure and stiffness on microgel deformation at a curved interface by elminating the necessity of electrostatic charge pairing. Microgel monomer and cross-linker content is expected to influence deformation at a curved interface. Microgel deformation and swelling were characterized via atomic force microscopy (AFM) and viscometry. A systematic study of colloidal-phase mediated heteroaggregation was performed at varied effective volume fractions with all microgel compositions. Scanning electron microscopy (SEM) and qNano pore translocation experiments were used to asses the microgel coverage on the resultant raspberry-like particles (RLPs). Results reveal that microgel composition has a strong influence on the efficiency (as determined by microgel coverage) of RLP fabrication. The compositional effects appear to be related to the degree of microgel spreading/deformation at the interface, which is coupled to the influence of packing on assembly fidelity. These findings are widely applicable to systems where microgel deformation occurs at a curved interface. We also demonstrate that qNano pore translocation experiments can be used as a high-throughput method to analyze RLP microgel coverage.

Influence of binary microgel phase behavior on the assembly of multi-functional raspberry-structured microgel heteroaggregates

“…We have seen that microgel stiffness, microgel network structure, and effective volume fraction of the colloidal phase influence particle interactions at a curved interface. 32 Recently, we have become interested in understanding how binary mixtures of microgels behave at such an interface. In particular, we are interested in understanding the influence of the mechanical stiffness of microgels on a binary mixture and the influence of microgel network structure on binary microgel dispersion interfacial behavior.…”

“…32 In the present study, we investigated the microgel arrangement within the colloidal phase by depositing a sessile drop of each highly packed binary microgel dispersion (Table 1) onto a glass substrate and immediately washing away the excess solution (Scheme 1). Due to the high effective colloidal volume fraction employed in these studies, we assume that the microgels have very short diffusion paths within the dispersed phase, resulting in a diffusion path-length of almost zero at the glass interface.…”

“…At least four weight fractions were used for each microgel composition and three trials were performed at each weight fraction. The swelling ratio, k , was determined by fitting the data to the Einstein-Batchelor equation as described previously 32 (Table S1). Microgel stiffness was also characterized using AFM nanoindentation.…”

Savitzky–Golay filter energy features-based approach to face recognition using symbolic modeling

“…The Savitzky-Golay filter preserves the peak shape property and reduces the signal-to-noise ratio. Hence, to take advantage of this property, it has been employed in various fields including the area of image processing for image enhancement [12] and enhancing the signal-to-noise ratio, video signals [13][14][15][16]. It has been devised to retain edge/ texture information, which is required in the classification stage [17].…”

Raspberry-Like Polysilsesquioxane Particles with Hollow-Spheres-on-Sphere Structure: Rational Design, Controllable Synthesis, and Catalytic Application

“…Micro-/nano-hierarchical particles can not only effectively avoid agglomeration of nanoparticles and easily be handled/recycled in comparison with nanoparticles but also produce porous structures during the assembling process [9,10]. Among hierarchical materials, raspberry-like particles with large central spheres surrounded by small spheres have gained increasing attention given their unique morphology, rough surfaces, large surface areas, and adjustable surface chemistry [11,12,13,14]. These raspberry-like nanoparticles have been investigated and utilized in versatile applications, such as the building blocks for superhydrophobic surfaces, delivery of drugs, optical materials, and as a heterogeneous catalyst [15,16].…”