Functional surface active monomers (surfmers) are molecules that combine the functionalities of surface activity, polymerizability, and reactive groups. This study presents an improved pathway for the synthesis of the active ester containing surfmer p-(11-acrylamido)undecanoyloxyphenyl dimethylsulfonium methyl sulfate (AUPDS). Further, the preparation of poly(methyl methacrylate) and polystyrene nanoparticles (NPs) by mini-emulsion polymerization using AUPDS is investigated, leading to NPs with active ester groups on their surface. By systematically varying reaction parameters and reagent concentrations, it was found that AUPDS feed concentrations between 2–4 mol% yielded narrowly distributed and stable spherical particles with average sizes between 83 and 134 nm for non-cross-linked NPs, and up to 163 nm for cross-linked NPs. By basic hydrolysis of the active ester groups in aqueous dispersion, the positive ζ-potential (ZP) was converted into a negative ZP and charge quantities determined by polyelectrolyte titrations before and after hydrolysis were in the same range, indicating that the active ester groups were indeed accessible in aqueous suspension. Increasing cross-linker amounts over 10 mol% also led to a decrease of ZP of NPs, probably due to internalization of the AUPDS during polymerization. In conclusion, by using optimized reaction conditions, it is possible to prepare active ester functionalized NPs in one stage using AUPDS as a surfmer in mini-emulsion polymerization.
A nanobiotecnologia é uma área do conhecimento que integra várias ciências, como a física, a química, a biologia e a ciência dos materiais. As nanopartículas, devido ao seu tamanho em nanoescala (em geral de 1 nm a 100 nm), apresentam propriedades novas ou melhoradas baseadas nas suas características específicas (tamanho, distribuição, morfologia, fase, composição, entre outras) quando comparadas a partículas de maiores dimensões provenientes da mesma fonte na qual as nanopartículas foram formadas. Nanopartículas metálicas (NPMs) são sistemas nanoestruturados que apresentam características físico-químico-biológicas dependentes da sua composição, tamanho e forma. Dentre as aplicações de NPMs, podem ser
The present study aimed to develop and optimize a method to obtain cellulose nanocrystals from the agricultural by-products rice husk and straw and to evaluate their electrostructural modifications in the presence of metallic ions. First, different particle formation conditions and routes were tested and analyzed by spectrophotometry, dynamic light scattering (DLS), and Zeta potential measurements. Then, electrostructural effects of ions Na(I), Cd(II), and Al(III) on the optimized nanoparticles were analyzed by atomic force microscopy (AFM), scanning electron microscopy (SEM), and electrical conductivity (EC) assessments. The produced cellulose nanocrystals adopted a rod-like shape. AFM height distribution and EC data indicated that the nanocrystals have more affinity in binding with Na(I) > Al(III) > Cd(II). These data suggest that the use of these cellulose nanocrystals in the bioremediation field is promising, both in metal sorption from wastewater and as an alternative for water desalination.
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