Synthesis of star polymethyl acrylate by SET-LRP at ambient temperature

Synthesis of an Acrylamide Copolymer Containing Nano-SiO2 by Ex Situ Cu(0)-Mediated SET-LRP

We report herein the synthesis of a novel star-shaped copolymer containing nano-SiO2 by single-electron transfer living radical polymerization (SET-LRP) in aqueous solution. The effects of polymerization conditions, such as the total amounts and molar ratios of the monomer, initiator, catalyst, ligand, and modified nano-SiO2, have been investigated through a series of experiments. The prepared acrylamide copolymers have been characterized by FTIR spectroscopy and 1H NMR spectrometry. The properties of the copolymers have been assessed by viscometry and rheometry. The results confirmed that the nano-SiO2 functional monomer was successfully combined in the SET-LRP. The optimum polymerization conditions were established through orthogonal experiments as a ratio of [AM] : [DMAEMA] : [I] : [CuBr] : [Me6TREN] of 674.4 : 35.5 : 1 : 1 : 2 at a total concentration of [AM] + [DMAEMA] of 2.5 mol/L. The appropriate concentration of the nano-SiO2 functional monomer (NSFM) was 0.5 wt% with respect to AM + DMAEMA. The rheology of the star-shaped copolymer exhibited a shear-thickening property when the shear rate exceeded a critical value (100 s−1). The AM/DMAEMA/NSFM copolymer displayed a higher viscosity than AM/DMAEMA at the same concentration. It was found that AM/DMAEMA/NSFM exhibited better salt and temperature tolerances.

Star Poly(β-amino esters) Obtained from the Combination of Linear Poly(β-amino esters) and Polyethylenimine

Composed of a three-dimensional structure with a central core and multiple radiating linear "arms", star polymers represent a significant type of branched macromolecular architectures. Due to the spatially defined core-shell-periphery architecture, star polymers have demonstrated their superiority in a variety of biomedical applications such as drug/gene delivery, molecular imaging, antibacterial agents, and so on. In this paper, we report the successful synthesis of a new type of star-shape poly(β-amino esters) with low molecular weight PEI as core and linear PAE (LPAE) as arms. This new star-PAE exhibits low cytotoxicity and high gene transfection efficacy. Star-PAE achieved between 264-fold and 14781-fold higher gene transfection efficiency of primary rat adipose derived mesenchymal stem cells in comparison with studies performed with the individual PEI and LPAE, respectively. The results suggest that star-PAE is a promising nonviral gene delivery vector.

Recent Developments in the Synthesis of Biomacromolecules and their Conjugates by Single Electron Transfer-Living Radical Polymerization

Single electron transfer-living radical polymerization (SET-LRP) represents a robust and versatile tool for the synthesis of vinyl polymers with well-defined topology and chain end functionality. The crucial step in SET-LRP is the disproportionation of the Cu(I)X generated by activation with Cu(0) wire, powder, or nascent Cu(0) generated in situ into nascent, extremely reactive Cu(0) atoms and nanoparticles and Cu(II)X₂. Nascent Cu(0) activates the initiator and dormant chains via a homogeneous or heterogeneous outer-sphere single-electron transfer mechanism (SET-LRP). SET-LRP provides an ultrafast polymerization of a plethora of monomers (e.g., (meth)-acrylates, (meth)-acrylamides, styrene, and vinyl chloride) including hydrophobic and water insoluble to hydrophilic and water soluble. Some advantageous features of SET-LRP are (i) the use of Cu(0) wire or powder as readily available catalysts under mild reaction conditions, (ii) their excellent control over molecular weight evolution and distribution as well as polymer chain ends, (iii) their high functional group tolerance allowing the polymerization of commercial-grade monomers, and (iv) the limited purification required for the resulting polymers. In this Perspective, we highlight the recent advancements of SET-LRP in the synthesis of biomacromolecules and of their conjugates.

Star Polymers

Recent advances in controlled/living polymerization techniques and highly efficient coupling chemistries have enabled the facile synthesis of complex polymer architectures with controlled dimensions and functionality. As an example, star polymers consist of many linear polymers fused at a central point with a large number of chain end functionalities. Owing to this exclusive structure, star polymers exhibit some remarkable characteristics and properties unattainable by simple linear polymers. Hence, they constitute a unique class of technologically important nanomaterials that have been utilized or are currently under audition for many applications in life sciences and nanotechnologies. This article first provides a comprehensive summary of synthetic strategies towards star polymers, then reviews the latest developments in the synthesis and characterization methods of star macromolecules, and lastly outlines emerging applications and current commercial use of star-shaped polymers. The aim of this work is to promote star polymer research, generate new avenues of scientific investigation, and provide contemporary perspectives on chemical innovation that may expedite the commercialization of new star nanomaterials. We envision in the not-too-distant future star polymers will play an increasingly important role in materials science and nanotechnology in both academic and industrial settings.

SET-LRP of acrylates catalyzed by a 1 penny copper coin

Controlled polymerization of acrylates can be catalyzed by one of the cheapest catalysts, a 1 pence coin.

Cu(0)-mediated living radical polymerization: recent highlights and applications; a perspective

Cu(0)-mediated living radical polymerization or single electron transfer living radical polymerization (Cu(0)-mediated LRP or SET-LRP) is a versatile polymerization technique that has attracted considerable interest during the past few years for the facile preparation of advanced materials.

Cu(0)-mediated polymerization of hydrophobic acrylates using high-throughput experimentation

In this paper the optimization of the Cu(0)-mediated polymerization of n-butyl acrylate and 2-methoxyethyl acrylate is reported using an automated parallel synthesizer.

Synthesis of multi-block copolymer stars using a simple iterative Cu(0)-mediated radical polymerization technique

A new iterative copper(0)-mediated radical polymerization approach is presented that represents a significant advance in the synthesis of high order multi-block star copolymers. The synthesis of these materials can now be achieved in high yield and with controlled structural complexity, with purification only required at the last step. The approach is general, facile and offers the opportunity to synthesize new copolymer stars.