- Award ID(s):
- 1707490
- PAR ID:
- 10184892
- Date Published:
- Journal Name:
- ACS symposium series
- Volume:
- 1284
- ISSN:
- 0097-6156
- Page Range / eLocation ID:
- 1-39
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
Metal complexes stabilized by appropriate ligands, particularly CuI/L systems, have proven powerful for the controlled polymerization of acrylates and other monomers by atom transfer radical polymerization (ATRP). The polymerization of acrylates by CuI/L systems, however, is haunted by interference of catalyzed radical termination (CRT), which reduces the chain-end fidelity. Other monomers do not appear to be affected by this phenomenon to any significant extent. The phenomenon appears to involve the formation of an organometallic intermediate by reversible radical trapping, as in organometallic mediated radical polymerization (OMRP). We summarize here the current knowledge and the efforts made to elucidate the CRT pathway and products.more » « less
-
Abstract Traditional mechanochemically controlled reversible‐deactivation radical polymerization (RDRP) utilizes ultrasound or ball milling to regenerate activators, which induce side reactions because of the high‐energy and high‐frequency stimuli. Here, we propose a facile approach for tribochemically controlled atom transfer radical polymerization (tribo‐ATRP) that relies on contact‐electro‐catalysis (CEC) between titanium oxide (TiO2) particles and CuBr2/tris(2‐pyridylmethylamine (TPMA), without any high‐energy input. Under the friction induced by stirring, the TiO2particles are electrified, continuously reducing CuBr2/TPMA into CuBr/TPMA, thereby conversing alkyl halides into active radicals to start ATRP. In addition, the effect of friction on the reaction was elucidated by theoretical simulation. The results indicated that increasing the frequency could reduce the energy barrier for the electron transfer from TiO2particles to CuBr2/TPMA. In this study, the design of tribo‐ATRP was successfully achieved, enabling CEC (ca. 10 Hz) access to a variety of polymers with predetermined molecular weights, low dispersity, and high chain‐end fidelity.
-
Abstract Atom transfer radical polymerization (ATRP) is a staple technique for the preparation of polymers with well‐defined architecture. In ATRP, the catalyst governs the equilibrium between propagating radicals and dormant species, thus affecting the polymerization control for a range of monomers and transferable atoms employed in the process. The design and the use of highly active catalysts could diminish the amount of transition metal complexes, extend ATRP to less active monomers and give access to new chain‐end functionalities. At the same time, very active catalysts can be involved in formation of organometallic species. Herein, the role of the catalyst on the ATRP equilibrium is carefully elucidated, together with recent observations on the impact of the catalyst nature on formation of organometallic species and relevant side reactions. Based on this knowledge, a perspective on the benefits and challenges that derive from the use of highly active ATRP catalysts is presented.
-
null (Ed.)The stringent control over the polymerization of less activated monomers remains one major challenge for Reversible Deactivation Radical Polymerizations (RDRP), including Atom Transfer Radical Polymerization (ATRP). Electrochemically mediated ATRP ( e ATRP) of a gaseous monomer, vinyl chloride (VC), was successfully achieved for the first time using a stainless-steel 304 (SS304) electrochemical reactor equipped with a simplified electrochemical setup. Controlled polymerizations were confirmed by the good agreement between theoretical and measured molecular weights, as well as the relatively narrow molecular weight distributions. Preservation of chain-end fidelity was verified by chain extension experiments, yielding poly(vinyl chloride) (PVC) homopolymers, block and statistical copolymers. The possibility of synthesizing PVC by e ATRP is a promising alternative to afford cleaner (co)polymers, with low catalyst concentration. The metal body of the reactor was also successfully used as a cathode. The setup proposed in this contribution opens an avenue for the polymerization of other gaseous monomers.more » « less
-
Catalysts are essential for mediating a controlled polymerization in atom transfer radical polymerization (ATRP). Copper-based catalysts are widely explored in ATRP and are highly efficient, leading to well-controlled polymerization of a variety of functional monomers. In addition to copper, iron-based complexes offer new opportunities in ATRP catalysis to develop environmentally friendly, less toxic, inexpensive, and abundant catalytic systems. Despite the high efficiency of iron catalysts in controlling polymerization of various monomers including methacrylates and styrene, ATRP of acrylate-based monomers by iron catalysts still remains a challenge. In this paper, we review the fundamentals and recent advances of iron-catalyzed ATRP focusing on development of ligands, catalyst design, and techniques used for iron catalysis in ATRP.more » « less