Radical Ring-Opening Copolymerization-Induced Self-Assembly (rROPISA)

Abstract

Radical ring-opening copolymerization-induced self-assembly (rROPISA) was performed by copolymerizing benzyl methacrylate (BzMA) and cyclic ketene acetals (CKA), such as 2methylene-4-phenyl-1,3-dioxolane (MPDL) or 5,6-benzo-2-methylene-1,3-dioxepane (BMDO), in heptane at 90 °C by reversible addition-fragmentation chain transfer (RAFT) polymerization from a poly(lauryl methacrylate) (PLMA) macro RAFT agent. The chain lengths of both the solvophilic macro-RAFT agent and the solvophobic block, together with the initial amount of CKA were independently varied to achieve various compositions. The amount of CKA in the copolymers was ranged from 4 to ~40 mol.% by adjusting the monomer stoichiometry, leading to nearly complete degradation for CKA contents above ~15 mol.%. rROPISA led to stable nanoparticles in all cases, ranging from 40 to 500 nm in diameter, depending on the experimental conditions, as assessed by DLS and TEM. Low average diameters and very narrow particle size distributions were obtained for CKA contents below 20 mol.%, except for a targeted solvophobic chain length of 300 that gave narrow particle size distributions up to 50 mol.% in CKA. Morphological investigation revealed the formation of spheres for all copolymer compositions, which was assigned to both the nature of the RAFT agent used and insertion of CKA in the solvophobic block, that prevent formation of other morphologies.

Ring-opening polymerization-induced crystallization-driven self-assembly of poly-L-lactide-block-polyethylene glycol block copolymers (ROPI-CDSA)

“…To date, most PISA processes have been reversible-deactivation radical polymerizations (RDRP) 1 , 2 , 11 , 14 , 31 , primarily reversible addition-fragmentation chain-transfer polymerization (RAFT-PISA) 11 , 14 , 31 – 34 . However, PISA can theoretically be extended to all types of living polymerizations and has been demonstrated with living anionic polymerization 35 , ring-opening metathesis (ROMP) of norbornenes 13 , 29 , radical ring-opening copolymerization (rROP) of cyclic ketenes 36 , and ring-opening polymerization (ROP) of N-carboxyanhydrides 37 . PISA has also been combined with CDSA, termed polymerization-induced crystallization-driven self-assembly (PI-CDSA), to generate crystalline self-assemblies in high concentrations (10–25% solids w/w) 15 , 16 , 38 .…”

Ring-opening metathesis polymerization-induced self-assembly (ROMPISA)

“…Then, water-insoluble 1,5-cyclooctadiene (COD) monomer was added to the macroinitiator solution to allow for one-pot aqueous ROMPISA under emulsion polymerization conditions. Typical for heterogeneous emulsion PISA systems, stable (PNB-(PEG 16 ) 2 )-b-PCOD diblock copolymer nanolatexes (i.e., kinetically trapped spherical micelles) of B200 nm size and low PD were obtained as judged by DLS and dry-state TEM analysis when a hydrophilic-to-hydrophobic molar ratio of 30 : 70 mol% was maintained. Currently identified corona-and core-forming monomer structures along with the catalysts and solvents utilized for ROMPISA in either organic or aqueous media are summarized in Table 1.…”

RAFT‐vermittelte polymerisationsinduzierte Selbstorganisation (PISA)

“…Aber auch die Auflösung des Partikelkerns könnte ein effektives Werkzeug sein. In diesem Sinne wurde von Guegain et al . kürzlich eine originelle Arbeit über die Synthese von abbaubaren Blockcopolymer‐Nanopartikeln veröffentlicht.…”