The synthesis of well-defined poly(vinylbenzyl chloride)-grafted nanoparticles via RAFT polymerization

Progress in surface-modified silicas for Cr(VI) adsorption: A review

Various toxic chemicals are discharging to the environment due to rapid industrialization and polluting soil, water, and air causing numerous diseases including life-threatening cancer. Among these pollutants, Cr(VI) or hexavalent chromium is one of the most carcinogenic and toxic contaminants hostile to human health and other living things. Therefore, along with other contaminants, the removal of Cr(VI) efficiently is very crucial to keep our environment neat and clean. On the other hand, silica has a lot of room to modify its surfaces as it is available with various sizes, shapes, pore sizes, surface areas etc. and the surface silanol groups are susceptible to design and prepare adsorbents for Cr(VI). This review emphases on the progress in the development of different types of silica-based adsorbents by modifying the surfaces of silica and their application for the removal of Cr(VI) from wastewater. Toxicity of Cr(VI), different silica surface modification processes, and removal techniques are also highlighted. The adsorption capacities of the surface-modified silica materials with other parameters are discussed extensively to understand how to select the best condition, silica and modifiers to achieve optimum removal performance. The adsorption mechanisms of various adsorbents are also discussed. Finally, future prospects are summarized and some suggestions are given to enhance the adsorption capacities of the surface-modified silica materials.

Computational Design of Radical Recognition Assay with the Possible Application of Cyclopropyl Vinyl Sulfides as Tunable Sensors

The processes involving the capture of free radicals were explored by performing DFT molecular dynamics simulations and modeling of reaction energy profiles. We describe the idea of a radical recognition assay, where not only the presence of a radical but also the nature/reactivity of a radical may be assessed. The idea is to utilize a set of radical-sensitive molecules as tunable sensors, followed by insight into the studied radical species based on the observed reactivity/selectivity. We utilize this approach for selective recognition of common radicals-alkyl, phenyl, and iodine. By matching quantum chemical calculations with experimental data, we show that components of a system react differently with the studied radicals. Possible radical generation processes were studied involving model reactions under UV light and metal-catalyzed conditions.

Sulfonated RAFT Copolymers as Heparin Mimetics: Synthesis, Reactivity Ratios, and Anticoagulant Activity

The glycosaminoglycan heparin is a clinically important anticoagulant drug, primarily used to reduce the risk of blood clots (thrombosis) during surgery. Despite its importance in medicine and its continuous use over many decades, heparin suffers from several limitations associated with its heterogeneity and its extraction from animal tissues. In order to address these limitations, reversible addition-fragmentation chain transfer polymerization is utilized to prepare a library of heparin mimetic copolymers from the sulfonated monomers sodium 4-styrene sulfonate, potassium-3-sulfopropyl acrylate, potassium-3-sulfopropyl methacrylate, and sodium-2-acrylamido-2-methyl-1-propane sulfonate. Copolymers are prepared using combinations of two different monomers in various ratios. Monomer reactivity ratios are also determined for some representative monomer combinations, and all polymers are characterized by ¹ H NMR spectroscopy and gel permeation chromatography. The anticoagulant activities of the copolymers are determined by activated partial thromboplastin time and thrombin clotting time assays and structure-activity relationships are explored.

pH and thermal dual-responsive poly(NIPAM-co-GMA)-coated magnetic nanoparticles via surface-initiated RAFT polymerization for controlled drug delivery

Herein, a novel type of multifunctional magnetic nanoparticles with dual thermal and pH-responsive behavior was fabricated as the carrier for delivery of doxorubicin (DOX). Fe₃O₄@SiO₂ magnetic nanoparticles, were grafted with polymer brushes consisting of poly (NIPAM-co-GMA) (PNG) chains via surface initiated reversible addition-fragmentation chain transfer (SI-RAFT) polymerization. The polymer brushes were then modified with hydrazine groups as DOX binding sites. The prepared multifunctional magnetic nanoparticles were characterized by FT-IR, ¹H NMR, XPS, TGA, DLS, VSM, GPC, TEM, and XRD analysis. The in vitro drug release of the multifunctional magnetic nanoparticles was examined at 37 °C (above LCST) and 25 °C (below LCST) in different pH media and exhibited excellent pH- and thermo-sensitive behavior. The results show that the Fe₃O₄@SiO₂@PNG-Hy fabricated via SI-RAFT polymerization is a viable candidate material for tumor treatment studies.

Surface-Initiated Controlled Radical Polymerization: State-of-the-Art, Opportunities, and Challenges in Surface and Interface Engineering with Polymer Brushes

The generation of polymer brushes by surface-initiated controlled radical polymerization (SI-CRP) techniques has become a powerful approach to tailor the chemical and physical properties of interfaces and has given rise to great advances in surface and interface engineering. Polymer brushes are defined as thin polymer films in which the individual polymer chains are tethered by one chain end to a solid interface. Significant advances have been made over the past years in the field of polymer brushes. This includes novel developments in SI-CRP, as well as the emergence of novel applications such as catalysis, electronics, nanomaterial synthesis and biosensing. Additionally, polymer brushes prepared via SI-CRP have been utilized to modify the surface of novel substrates such as natural fibers, polymer nanofibers, mesoporous materials, graphene, viruses and protein nanoparticles. The last years have also seen exciting advances in the chemical and physical characterization of polymer brushes, as well as an ever increasing set of computational and simulation tools that allow understanding and predictions of these surface-grafted polymer architectures. The aim of this contribution is to provide a comprehensive review that critically assesses recent advances in the field and highlights the opportunities and challenges for future work.

A CTA-shuttled R-group approach: a versatile synthetic tool towards well-defined functional cylindrical polymer brushes via RAFT polymerization

We report a novel three-step strategy toward polyCTA for the synthesis of cylindrical polymer brushes via “CTA-shuttled” RAFT R-approach polymerization. Post functionalizations on the CTA residue are also discussed.

Functionalization of Planet-Satellite Nanostructures Revealed by Nanoscopic Localization of Distinct Macromolecular Species

The development of a straightforward method is reported to form hybrid polymer/gold planet-satellite nanostructures (PlSNs) with functional polymer. Polyacrylate type polymer with benzyl chloride in its backbone as a macromolecular tracer is synthesized to study its localization within PlSNs by analyzing the elemental distribution of chlorine. The functionalized nanohybrid structures are analyzed by scanning transmission electron microscopy, electron energy loss spectroscopy, and spectrum imaging. The results show that the RAFT (reversible addition-fragmentation chain transfer) polymers' sulfur containing end groups are colocalized at the gold cores, both within nanohybrids of simple core-shell morphology and within higher order PlSNs, providing microscopic evidence for the affinity of the RAFT group toward gold surfaces.

Surface-initiated SET living radical polymerisation for the synthesis of silica–polymer core–shell nanoparticles

We report the use of surface-initiated single-electron transfer living radical polymerisation (SI SET-LRP) to prepare inorganic–organic core–shell nanoparticles with functional grafted chains of high molecular weight.

A new high-capacity metal ion-complexing gel containing cyclen ligands

“Hairy” nano-scale objects cross-linked into a high-capacity metal-binding hydrogel.

Synthesis of polymers and nanoparticles bearing polystyrene sulfonate brushes for chemokine binding

This paper describes the synthesis of polymers and silica nanoparticles, both bearing polystyrene sulfonate brushes, and the measurement of their binding affinity for the chemokine monocyte chemoattractant protein-1 (MCP-1) in monomeric and dimeric form.

Selective patterning of gold surfaces by core/shell, semisoft hybrid nanoparticles

The generation of patterned surfaces with well-defined nano- and microdomains is demonstrated by attaching core/shell, semisoft nanoparticles with narrow size distribution to microdomains of a gold-coated silicon wafer. Near monodisperse nanoparticles are prepared using reversible addition-fragmentation chain transfer (RAFT) polymerization, initiated from a silica surface, to prepare a polystyrene shell around a silica core. The particles are then used as-prepared, or after aminolysis of the terminal thiocarbonyl group of the polystyrene shell, to give thiol-terminated nanoparticles. When gold-coated silicon wafers are immersed into very dilute suspensions of these particles (as low as 0.004 wt%), both types of particles are shown to adhere to the gold domains. The thiolated particles adhere selectively to the gold microdomains, allowing for microdomain patterning, while particles that contain the trithiocarbonate functionality lead to a much more even coverage of the gold surface with fewer particle aggregations.

Preparation of core–shell particles by surface-initiated cycloketyl radical mediated living polymerization

Core–shell particles were prepared by surface-initiated cycloketyl radical mediated living polymerization, achieving deliberate control over the particle size and uniformity. It has significant potential for industrial application.

Spherical Gold-Nanoparticle Assemblies with Tunable Interparticle Distances Mediated by Multifunctional RAFT Polymers

A strategy for the controlled assembly of gold nanocrystals into dispersed three-dimensional superstructures is presented. A multifunctional RAFT agent was used to prepare multiblock polystyrene (4.4-17.8 kDa) with trithiocarbonate groups as junctions between the individual blocks. Addition of these polymers to two-phase Brust-Schiffrin gold nanoparticles (4.1 nm) resulted in the formation of stable gold-nanoparticle assemblies dispersed in toluene. TEM analysis revealed that the interparticle distances in these superstructures can be tuned over an unprecedented wide range by employing multiblock polymers with an adjusted degree of polymerization and thus tailored trithiocarbonate distances. Cross-linking of the gold nanoparticles in the assemblies by multifunctional trithiocarbonates was proven by AFM showing partly preserved globular shape after deposition on a solid substrate. The reported strategy is expected to prove useful when interparticle distances in nanoparticle assemblies need to be tuned in a liquid phase or on surfaces.