Effects of Polymer Micelles of Alkylated Polyethylenimines on Generation of Gold Nanoparticles

Abstract

Mono- and di-alkylated polyethylenimines (PEI-1R, PEI-2R) were synthesized and used as both reductants, by exploiting the functionality of the polyethylenimine's (PEI) amino groups, and stabilizers able to protect nascent gold nanoparticles generated from hydrogen tetrachloroaurate (HAuCl4). From TEM images of the stained polymers, it is clear that the polymer micelles are round and well-structured when formed from PEI-2R, fused and less well-structured when formed from PEI-1R, and totally nonstructured when formed from PEI. These findings coincide with the results found by using pyrene as a probe to investigate aggregation behavior, where PEI-2R with a fluorescence intensity ratio (I1/I3) of 1.48 forms the more closely packed polymer micelles than PEI-1R (I1/I3 = 1.64) and PEI (I1/I3 = 1.72). The use of the highly alkylated polymer micelle (PEI-2R) results in the fastest reduction of HAuCl4, and gives the most effective protection to the generated gold nanoparticles. When used at higher polymer concentrations than required for micelle formation, it was found that polymer hydrophobicity was highly influential in directing the nanoparticle's morphology, i.e., the resulting polymer micelles were labeled with perfect and round necklace-like gold nanoparticles when PEI-2R was used, and imperfect and less round gold nanoparticles when PEI-1R was employed. These structures were totally absent when PEI was used. The use of alkylated PEI, being able to act simultaneously as both a reductant and as a very effective protective agent, greatly simplifies the process used for preparing gold nanoparticles.

Synthesis of cationic hyperbranched multiarm copolymer and its application in self-reducing and stabilizing gold nanoparticles

“…According to previous reports [32][33][34][35][36] and our findings presented here, we assumed that the large amount of tertiary amino groups in HBPO-star-PDEAEMA is significant for the preparation of AuNPs. To validate our assumption, we selected some hyperbranched polymers without amino groups as the controls, such as hyperbranched polyglycerol (HPG) and hyperbranched polyester H20, to prepare AuNPs through the same approach.…”

The Characteristic Self-assembly of Gold Nanoparticles over Indium Tin Oxide (ITO) Substrate

“…The primary amine groups in alkyl chains, which is well known to interact with gold ions and the corresponding reduced metal, is expected to exhibit a significant effect on the self-assembly of Au NPs. [25][26][27] William et al reported an incomplete coverage of gold colloids (ranged in 25-120 nm) on indium tin oxide (ITO) surface, i.e., Au NPs were deposited as a discontinuous layer with a large gap among the adjacent particles.…”

Gold nanoparticles prepared using polyethylenimine adsorbed onto montmorillonite

“…Both modes of action are governed to a large extent by the pH-dependent degree of cationic charge density. In our previous study, alkylated PEI was used as both a stabilizer and a reducing agent to prepare nanoscale metal particles [8]. It was found the alkyl groups directed the conformation of PEI chains by means of the formation of polymer micelles (soft template) resulting in a system giving effective protection to newly generated gold nanoparticles.…”