In Situ Synthesis and Characterization of Silver/Polymer Nanocomposites by Thermal Cationic Polymerization Processes at Room Temperature: Initiating Systems Based on Organosilanes and Starch Nanocrystals

Abstract

New methods for the preparation of silver nanoparticles/polymer nanocomposite materials by thermal cationic polymerization of ε-caprolactone (ε-CL) or α-pinene oxide (α-PO) at room temperature (RT) and under air were developed. The new initiating systems were based on silanes (Si), starch nanocrystals (StN) and metal salts. Excellent polymerization profiles were revealed. It was shown that silver nanoparticles (Ag(0) NPs) were in situ formed and that the addition of StN improves the polymerization efficiency. The as-synthesized nanocomposite materials contained spherical nanoparticles homogeneously dispersed in the polymer matrices. Polymers and nanoparticles were characterized by gel permeation chromatography (GPC), X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and UV-vis spectroscopy. A coherent picture of the involved chemical mechanisms is presented.

N-Vinylcarbazole: As an Additive for Thermal Polymerization at Room Temperature with in situ Formation of Ag(0) Nanoparticules

“…They ensure good to excellent polymerizations are always obtained leading to tack free surface coatings after only 3 min. A concomitant increase of the band at 1080 cm is also observed due to the formation of the polyether network and polyacrylate, respectively (Figure 5B) [30][31][32]. A high Si-H consumption is also found in agreement with the proposed mechanisms (Schemes 1 and 2) ( Figure 5C).…”

“…A quite good polymerization is always obtained at RT and under air leading to tack free surface coatings (gel time ~5 min and tack free time ~1 h). It is evident the important decrease of the typical epoxy band at 770-830 cm due to ether group formed during the ring-opening polymerization ( Figure 4B) [30][31][32][33][34][35][36][37]. Almost no inhibition is noted, as a short period is already requested for the solubilization of the silane into the formulation.…”

“…This approach consists of producing a radical R • (from an organosilane), to initiate FRP, that can be easily oxidized by a silver salt (e.g., AgSbF6) leading to R + , which corresponds to the ROP initiating structure (Scheme 2) [30][31][32] However, the nature of the primary radicals produced from the organosilane is crucial for getting a high polymerization efficiency, as they should be characterized by excellent oxidation properties; moreover, the resulting radicals and cations must be efficient structures for the FRP and CP reactions, respectively [33][34][35][36][37]. Even if a lot of systems have been developed in the last years [33][34][35][36][37][38][39][40][41][42], the search for novel additives being able to improve the radical and/or cationic polymerization processes still appears as a challenge.…”

Silver Metallic Cyclodextrin‐Core Star mPEG

“…The peaks at binding energy of 366.5 and 372.5 eV correspond to Ag 3d 5/2 and 3d 3/2 , respectively. [35,36] The results clearly demonstrate that SM-CD-SPEG can be prepared by an appropriate reaction condition. Comparison of feed and actual compositions of the metallic polymer samples indicates that E50A exhibited best result (Table 1).…”

“…S20A was further selected for XPS analysis (Figure b). The peaks at binding energy of 366.5 and 372.5 eV correspond to Ag 3d 5/2 and 3d 3/2 , respectively . The results clearly demonstrate that SM‐CD‐SPEG can be prepared by an appropriate reaction condition.…”