Hairy Core–Shell Nanoparticles via RAFT: Where are the Opportunities and Where are the Problems and Challenges?

Abstract

The preparation of hairy core-shell nanoparticles including (crosslinked) micelles, unimolecular micelles such as star polymers with block structures in each arm and surface grafted nanoparticles such as inorganic particles via the RAFT process are discussed. The RAFT process is certainly a highly versatile process. However, it should not be forgotten that RAFT polymerization is a process, i.e., superimposed on a conventional free radical process. Furthermore, the livingness of the process is dependent on the accessibility of the RAFT group, which can be hampered in certain approaches such as star synthesis and surface grafting from nanoparticles. Nevertheless, the RAFT process is a versatile toolbox that offers good solutions to a range of problems in the preparation of hairy nanoparticles.

Hairy nanoparticle assemblies as one-component functional polymer nanocomposites: opportunities and challenges

“…Two of the most widely used grafting-from techniques are Atom Transfer Radical Polymerization (ATRP) [104,[107][108][109] and Reversible Addition Fragmentation Transfer (RAFT) [110] . These are both mechanisms that are tolerant of a wide variety of functional groups on the monomer, greatly expanding the library of coronas available for HNP synthesis.…”

“…RAFT is another highly versatile technique that requires mild conditions and offers a wide range of monomers and solvents to choose from. [110] Benicevicz et al were one of the first to establish a grafting-from route for HNPs using RAFT-silane agents to functionalize silica and polymerize PS and PMMA at high yields while controlling graft density and molecular weight of grafted chains. [111,112] RAFT offers one major advantage over ATRP: it uses a thioester RAFT agent as opposed to a transition metal ATRP catalyst, eliminating the heavy metal contamination of the final product.…”

“…HNPs; first creating BCP micelles [110] or stars, [113] and then crosslinking the inner block to form the rigid particle.…”

Living Radical Polymerization by the RAFT Process – A Third Update

“…include those on the kinetics and mechanism of RAFT polymerization, [26,27] RAFT agent design and synthesis, [28] the use of RAFT to probe the kinetics of radical polymerization, [29] microwaveassisted RAFT polymerization, [30,31] RAFT polymerization in microemulsion, [32] end-group removal/transformation, [33][34][35][36] the use of RAFT in organic synthesis, [37] the combined use of RAFT polymerization and click chemistry, [38] the synthesis of star polymers and other complex architectures, [39][40][41][42] the synergistic use of RAFT polymerization and ATRP, [43,44] the synthesis of self assembling and/or stimuli-responsive polymers, [45][46][47] and the use of RAFT-synthesized polymers in green chemistry, [48] polymer nanocomposites, [49][50][51] drug delivery and bioapplications, [41,46,47,[52][53][54][55][56][57][58][59][60] and applications in cosmetics [61] and optoelectronics. [62] The process is also given substantial coverage in most recent reviews that, in part, relate to polymer synthesis, living or controlled polymerization or novel architectures.…”

Surface‐Initiated Reversible Addition Fragmentation Chain Transfer (RAFT) Polymerization of Styrene from Laponite Clay Surfaces

“…[17,23,24] In an ideal scenario free RAFT agent slows down the polymerization of free polymer allowing controlled grafting from the surface. In summary, 3 was used to control the polymerization occurring at the surface whilst 4 was added in solution to control polymerization of the free polymer.…”