skip to main content
US FlagAn official website of the United States government
dot gov icon
Official websites use .gov
A .gov website belongs to an official government organization in the United States.
https lock icon
Secure .gov websites use HTTPS
A lock ( lock ) or https:// means you've safely connected to the .gov website. Share sensitive information only on official, secure websites.

Explore Research Products in the PAR
It may take a few hours for recently added research products to appear in PAR search results.


  • NSF Public Access
  • Search Results
  • Silica‐PMMA hairy nanoparticles prepared via phase transfer‐assisted aqueous miniemulsion atom transfer radical polymerization
Title: Silica‐PMMA hairy nanoparticles prepared via phase transfer‐assisted aqueous miniemulsion atom transfer radical polymerization
Abstract Hairy nanoparticles (HNPs) constitute a class of hybrid nanocomposites that are resistant to aggregation and agglomeration, although the green, large‐scale synthesis of HNPs remains a challenge. In this work, 25 nm‐diameter silica‐core HNPs with a poly(methyl methacrylate) (PMMA) shell were synthesized using a graft‐from approach in aqueous miniemulsion, employing atom transfer radical polymerization with activators regenerated by electron transfer (ARGET‐ATRP). In particular, this work used tetrabutylammonium bromide (TBAB)‐assisted phase transfer of monomer, markedly improving upon earlier methods by showing that phase transfer could take place in the absence of organic solvents. Furthermore, syntheses with selected monomer addition rates produced HNP graft densities ranging from 0.011 to 0.017 chains/nm2and shell thicknesses ranging from 2.5 to 11 nm. Finally, analysis of reaction kinetics revealed that shell growth reached completion in as little as 2 hr, confirmed by the synthesis of >1 g of PMMA‐shell HNPs in a reduced timeframe.  more » « less
Award ID(s):
1905403
PAR ID:
10453521
Author(s) / Creator(s):
 ;  ;  ;  
Publisher / Repository:
Wiley Blackwell (John Wiley & Sons)
Date Published:
Journal Name:
Journal of Polymer Science
Volume:
58
Issue:
17
ISSN:
2642-4150
Page Range / eLocation ID:
p. 2310-2316
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
More Like this
  1. ; ; ; ; ; (, Molecules)
    Structurally well-defined polymer-grafted nanoparticle hybrids are highly sought after for a variety of applications, such as antifouling, mechanical reinforcement, separations, and sensing. Herein, we report the synthesis of poly(methyl methacrylate) grafted- and poly(styrene) grafted-BaTiO3 nanoparticles using activator regeneration via electron transfer (ARGET ATRP) with a sacrificial initiator, atom transfer radical polymerization (normal ATRP), and ATRP with sacrificial initiator, to understand the role of the polymerization procedure in influencing the structure of nanoparticle hybrids. Irrespective of the polymerization procedure adopted for the synthesis of nanoparticle hybrids, we noticed PS grafted on the nanoparticles showed moderation in molecular weight and graft density (ranging from 30,400 to 83,900 g/mol and 0.122 to 0.067 chain/nm2) compared to PMMA-grafted nanoparticles (ranging from 44,620 to 230,000 g/mol and 0.071 to 0.015 chain/nm2). Reducing the polymerization time during ATRP has a significant impact on the molecular weight of polymer brushes grafted on the nanoparticles. PMMA-grafted nanoparticles synthesized using ATRP had lower graft density and considerably higher molecular weight compared to PS-grafted nanoparticles. However, the addition of a sacrificial initiator during ATRP resulted in moderation of the molecular weight and graft density of PMMA-grafted nanoparticles. The use of a sacrificial initiator along with ARGET offered the best control in achieving lower molecular weight and narrow dispersity for both PS (37,870 g/mol and PDI of 1.259) and PMMA (44,620 g/mol and PDI of 1.263) nanoparticle hybrid systems. 
    more » « less
  2. ; ; (, Nanotechnology)
    Abstract This study presents an eco-friendly mechanochemical synthesis of cesium lead bromide (CsPbBr3), eliminating the need of organic solvents and high temperatures. The synthesized CsPbBr3powder is used to fabricate poly(methyl methacrylate) (PMMA)-CsPbBr3films and CsPbBr3nanocrystals (NCs). The photoluminescence (PL) peaks of the emission light are centered at 541 nm, 538 nm, and 514 nm for the CsPbBr3powder, PMMA-CsPbBr3films, and CsPbBr3NCs, respectively, correlating with crystal sizes of 0.96, 0.56, and 0.12μm, respectively. The PL lifetime analysis reveals decay times ( τ 1 , τ 2 ) of (4.18, 20.08), (5.7, 46.99), and (5.81, 23.14) in the units (ns, ns) for the CsPbBr3powder, PMMA-CsPbBr3films, and CsPbBr3NCs, respectively. The PL quantum yield of the CsPbBr3NCs in toluene is 61.3%. Thermal activation energies for thermal quenching are 217.48 meV (films) and 178.15 meV (powder), indicating improved thermal stability with the PMMA encapsulation. The analysis of the PL intensity decay from water diffusion in the PMMA-CsPbBr3films yields 1.70 × 10−12m2s−1for the diffusion coefficient of water, comparable to that for water diffusion in pure PMMA. This work demonstrates a scalable, sustainable strategy for CsPbBr3synthesis and stability enhancement for optoelectronic applications. 
    more » « less
  3. ; ; ; (, Macromolecular Rapid Communications)
    Abstract Photomediated reversible addition fragmentation chain transfer (RAFT) step‐growth polymerization is performed using a trithiocarbonate‐based chain transfer agent (CTA) and acrylate‐based monomers both with and without a photocatalyst. The versatility of photo‐mediated RAFT step‐growth is demonstrated by one‐pot synthesis of a graft copolymer via sequential monomer addition. Furthermore, oxygen‐tolerant photo‐mediated RAFT step‐growth is demonstrated, facilitated by the appropriate selection of photocatalyst and solvent pair (zinc tetraphenyl porphyrin [ZnTPP] and dimethyl sulfoxide [DMSO]), enabling ultralow volume polymerization under open‐air conditions. 
    more » « less
  4. ; ; ; (, Materials Advances)
    Polymer nanoparticles are an emerging class of materials with potential impact in sensing, catalysis, imaging, cosmetics, and therapeutics. Here, a collection of graft polymers with conjugated polythiophene backbones were synthesized via a grafting-to approach. We functionalized polythiophene backbones with side chains of either poly(3-hexylthiophene) (P3HT), poly(ethylene oxide), or poly(methyl methacrylate) (PMMA) via copper-catalyzed azide–alkyne click chemistry. The backbones, graft polymers and a linear poly(3-hexylthiophene) were fabricated into nanoparticles through precipitation in aqueous media. We measured the absorption and emission spectra of the polymers dissolved in chloroform and as nanoparticles suspended in water. Compared to linear P3HT, all graft polymer nanoparticles exhibit higher quantum yields. Moreover, the addition of PMMA side chains increased the quantum yield by more than two orders of magnitude. This versatile approach to conjugated graft copolymer synthesis demonstrates a route for enhancing photoluminescence of conjugated polymer nanoparticles that could be beneficial for a variety of applications, such as biosensing and bioimaging. 
    more » « less
  5. ; ; ; ; ; ; ; (, Optical Materials Express)
    Core/shell nanoparticles composed of a silica core over which a propargyl methacrylate (PMA) shell was polymerized around were synthesized. To employ the shell coating, the surface of the silica nanoparticles (SiNPs) was modified with an alkene-terminated organometallic silane linker that allowed for the covalent attachment of a poly(propargyl methacrylate) (pPMA) shell. The alkyne groups resulting from the pPMA shell were utilized in copper(I)-catalyzed azide/alkyne cycloaddition (CuAAC) reactions to attach azide-modified Förster resonance energy transfer (FRET) pairs of naphthalimide (azNap), rhodamine B (azRhod), and silicon phthalocyanine (azSiPc) derivatives to the shell surface. The luminescence of the system was manipulated by the covalent attachment of one, two, or three of the fluorophores resulting in no energy transfer, one energy transfer, or two energy transfers, respectively. When all three fluorophores were attached to the core/shell particles, an excitation of azNap with a wavelength of 400 nm resulted in the sequential energy transfer between two FRET pairs and the sole emission of azSiPc at 670 nm. These particles may have applications as bioimaging probes as their luminescence is easily detected using fluorescence microscopy. 
    more » « less
  • Citation Formats
  • MLA
  • APA
  • Chicago
  • BibTeX
  • Save / Share this Record
  • Send to Email