D70-g-PAA20. (1) T = 40°C, (2) T = 60°C. Hydrazine as reducing agent Ag sols, obtained using hydrazine hydrate as reductant, display intensive plasmon absorption bands for all nanosystems synthesized in linear and branched polyelectrolyte Napabucasin solubility dmso matrices (Figure 5). For linear

PAA, only one broad peak was registered in the range from 365 to 475 nm. Existence of two well-dedicated maxima for sols prepared in branched polymer matrices can be referred to different size fractions or to plasmon absorption of particles with anisotropic form. Both statements were proved by analysis of TEM images of silver sols (Figure 6a). Nanosystems were polydisperse (area distribution histogram is shown in Figure 6b), and single particles with average MG-132 mw size of 130 ± 10 nm have anisotropic form. Large-scaled TEM revealed the presence of multi-branched Ag particles

(Figure 7). Formation of hyperbranched anisotropic Ag nanostructures in aqueous solution was quite surprising; it is known that silver has a highly symmetric crystal structure. Similar anisotropic structures of Ag particles were described in [30–32]. It was concluded that hyperbranched structures result from slow-reducing nature (kinetically controlled growth) and shape-directing role of citric acid as reductant. In our case, the control of the Ag particle shape is realized also by the peculiarities of the host branched polymer internal structure. The most efficient matrix was D70-g-PAA20, i.e., the one formed by the macromolecules having the highest compactness (Table 1). Figure 5 UV-vis absorption spectra of silver sols synthesized in the polymer matrices. D70-g-PAA20 VX-770 supplier (1), D70-g-PAA5 (2), and PAA (3). T = 20°C. The reductant is hydrazine hydrate. Figure 6 TEM image (a) and area of nanoparticle distribution (b) in silver sols synthesized in D70-PAA5 matrix. The reductant Y-27632 2HCl is hydrazine hydrate. Figure 7 TEM image of a single multi-branched silver particle. The reductant is hydrazine

hydrate. Conclusions The present study presents a study of Ag sols obtained in linear and branched polyelectrolyte matrices. It was revealed the effect of the internal structure of host polymer matrices depended on silver nanoparticle size, morphology, and stability. The polyelectrolyte linear polymer matrices were less efficient for silver sol manufacturing in comparison with branched ones for all reductants used. Something already contemplated and demonstrated for silver sol, synthesized in situ in the same polymer matrices using ascorbic acid as the reducing agent [33]. It was established that the temperature of synthesis and the reductant choice drastically affect the size and shape of silver nanoparticles obtained. Stable Ag sols could not be synthesized in linear PAA matrix at 80°C, while colloids synthesized in branched matrices remained stable. Authors’ information VC is a Ph.D. student in the Macromolecular Department of Kiev Taras Shevchenko National University.