A new precursor (Ag/CS/PNIPA) arranged as a nanogel (nanoreactor) is obtained from the aqueous mixture of Ag, chitosan (CS) and poly(N-isopropylacrylamide) (PNIPA). A model synthetic system based on the thermally induced aqueous silver ions-CS reaction to form silver nanoparticles (AgNP) is used as a starting point to assess the PNIPA role as a thermo-sensitive additive of synthesis in a low content for the production of size-controlled AgNP. As expected, the PNIPA phase transition produced by the temperature increase leads to chitosan nanogel contraction, lowering the diffusion of ionic species. PNIPA behaves as a successful additive between 5.6 and 10.5 wt% of content blended with chitosan, noticeably improving AgNP nucleation during thermal treatment at 90 °C. Higher PNIPA contents are less effective in achieving size control and broader size distributions are generated. The PNIPA effect on the nanoreactor structure is characterized by rheology, modelled and analyzed against the AgNP morphology obtained.
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http://dx.doi.org/10.1016/j.carbpol.2022.119374 | DOI Listing |
Int J Mol Sci
December 2024
Department of Physical Chemistry and Biophysics, Pharmaceutical Faculty, Wroclaw Medical University, Borowska 211, 50-556 Wroclaw, Poland.
The synthesis of poly(N-isopropyl acrylamide) (pNIPA)-based polymers via the surfactant-free precipitation polymerization (SFPP) method produced thermosensitive nanospheres with a range of distinctive physicochemical properties. Nano- and microparticles were generated using various initiators, significantly influencing particle characteristics, including the hydrodynamic diameter (D), which varied from 87.7 nm to 1618.
View Article and Find Full Text PDFMacromol Rapid Commun
November 2024
Faculty of Science and Letters, Department of Chemistry, Soft Materials Research Laboratory, Istanbul Technical University, Maslak, Istanbul, 34469, Turkey.
Weakly anionic semi-interpenetrating polymer networks (semi-IPNs), comprised of copolymer poly(N-isopropylacrylamide-co-methacrylic acid) P(NIPA-MA) and linear poly(acrylamide) (LPA) chains as macromolecular crowding agent, are designed to evaluate pH-induced swelling and elasticity. Uniaxial compression testing after swelling in various pH-conditions is used to analyze the compressive elasticity as a function of swelling pH and LPA-content. The swelling of P(NIPA-MA)/LPA semi-IPNs is strongly pH-dependent due to MA units incorporated into the copolymer network which already exhibits temperature-sensitivity by presence of PNIPA counterpart.
View Article and Find Full Text PDFPolymers (Basel)
September 2024
Department of Physical Chemistry and Biophysics, Pharmaceutical Faculty, Wroclaw Medical University, Borowska 211, 50-556 Wroclaw, Poland.
Polymers (Basel)
March 2024
Department of Physical Chemistry and Biophysics, Pharmaceutical Faculty, Wroclaw Medical University, Borowska 211, 50-556 Wroclaw, Poland.
The aim of this study was to characterize and compare the zeta potential of particles sensitive to external thermal stimuli. Poly N-(isopropyl) acrylamide (PNIPA) was selected as the thermosensitive polymer with a volume phase transition temperature (VPTT) between 32 and 33 °C. The hydrodynamic diameter (D) of the nanoparticles was measured by dynamic light scattering.
View Article and Find Full Text PDFJ Chromatogr A
December 2023
School of Chemistry, Sun Yat-sen University, Guangzhou, 510006, China. Electronic address:
Poly(N-isopropylacrylamide) thermosensitive hydrogel tube tip solid-phase extraction/ultra-high liquid chromatography-mass spectrometry (UPLC-MS/MS) method was developed for analysis of methylimidazoles in beverages. Thermosensitive poly(N-isopropylacrylamide) (PNIPA) hydrogel solid-phase extraction (SPE) medium was prepared on the surface of highly internal phase emulsion (HIPE) porous polymer by thermally initiated polymerization in a tube tip. The temperature sensitive SPE medium has the characteristics of high porosity and high specific surface area.
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