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Poly(N-isopropylacrylamide) (PNIPAM) nanogels were prepared by emulsion polymerization using sodium dodecyl sulfate (SDS) and employed as a capping agent in platinum nanoparticle (Pt NP) synthesis by liquid-phase reduction with hydrogen gas. When the PNIPAM nanogels were used without removing SDS, that is, a slight amount of SDS was included in the reaction solution, Pt nanocubes (NCs) were predominantly produced (>80%). The proportion of the resultant Pt NCs was much higher than that obtained using the PNIPAM linear polymer (∼60%). To clarify the effects of the three-dimensional polymer network and SDS, we synthesized Pt NPs using the PNIPAM nanogel without SDS (SDS-free PNIPAM nanogel) and found that Pt NCs are rarely formed, and most NPs obtained have an irregular shape. When only SDS was used as a capping agent, NCs were hardly obtained, but other polyhedral NPs were formed. Furthermore, the use of SDS together with the PNIPAM polymer led to the decrease in the proportion of the Pt NCs compared with that obtained using only the linear polymer. These results indicate that the enhancement of the Pt NC proportion using the PNIPAM nanogel with SDS is attributable to not only the three-dimensional polymer network of the PNIPAM nanogel but also the assist of SDS as a capping agent.

We report a new insight into the chemical gelation process of poly(N-isopropylacrylamide) (PNiPAAm) hydrogel elucidated on the basis of the in situ observations with time-resolved Fourier-transform...

We have prepared silica particles grafted with poly(N-isopropylacrylamide) (PNIPA) copolymers as adsorbent for the temperature-swing adsorption of bovine serum albumin (BSA) in water, where vinylbe...

Internal structures of the opaque poly(N-isopropylacrylamide) gel obtained at the preparation temperature (TP) higher than 24.5 °C was found to have hierarchical structures by means of a combined small-angle-scattering (CSAS) method of small-angle light scattering (SALS), ultra-small-angle neutron scattering (USANS), and small-angle neutron scattering (SANS) with an aid of laser scanning confocal microscopy (LSCM). The combined CSAS and LSCM studies revealed that a global structure of the gels had a sponge-like two-phase structure. The polymer-rich phase of the sponge was filled with microgels having highly cross-linked network (“tight network”) chains that are interconnected by loosely cross-linked network (“loose network”) chains swollen with water, while the other phase of the sponge was mostly composed of water. These two phases were cocontinuous in three-dimensional space, hence, forming macroscopic gels. The SALS and USANS studies clarified that the sponge had a characteristic spacing of ≈12 μm and ...

Laser scanning confocal micrographs for blends of poly(styrene-ran-butadiene) (SBR) and polybutadiene (PB) demonstrated the existence of fine structures inside one of the well-characterized macroscopically phase-separated bicontinuous domains, in the depth range of the blends belonging to the bulk. The average size of the fine structures was on the submicrometer length scale, while the characteristic spacing of the macroscopically phase-separated domains was on the order of 10 μm. Fluorescence laser scanning confocal micrographs revealed that the fine structures exist only in the SBR-rich phase. Although the driving force for the formation of the fine structures needs to be investigated further, a small amount of PB molecules in the SBR-rich domains seems to play an important role. Illumination and highlights were shed on the advantage of using laser scanning confocal microscopy for investigation of fine structures in the polymer blends.

Internal structures of translucent poly(N-isopropylacrylamide) gel were for the first time observed by laser scanning confocal microscopy (LSCM). The observed image reflected the mesoscopic internal structures in the gel due to the “fixed concentration fluctuations” of network polymers as described in the text. Three-dimensional internal structures in the gel constructed from a series of the cross section images taken by the LSCM revealed that the gel had a bicontinuous domain structure consisting of regions dense and sparse in polymer networks.

Fine palladium (Pd) particles, which have a diameter of 4−5 nm and are coordinated with the poly(2-vinylpyridine) homopolymer (P2VP) or poly(2-vinylpyridine)-block-polyisoprene diblock copolymer (P2VP-b-PI), were prepared by the reduction of palladium acetylacetonate (PdII(acac)2) with 1-propanol in the dilute benzene solution of P2VP or P2VP-b-PI. These Pd “nanoparticles” were selectively incorporated into a particular region of microdomains by casting a solution comprised of the Pd nanoparticles, P2VP-b-PI, and chloroform as a solvent into film specimens. The nanoparticles coordinated with P2VP were selectively incorporated into the P2VP domains, while those coordinated with P2VP-b-PI were around the interface between the P2VP and PI domains.

Gel forme d'acrylamide N,N'-methylene bisacrylamide et chlorure de (methacrylamidopropyl) trimethylammonium

Transition de phase de spheres de gels ionises de N-isopropylacrylamide avec des diametres compris entre 0,2 et 1 μm