A methacrylic polymer undergoing highly efficient para-fluoro substitution reactions\ud is presented. A series of well-defined poly(2,3,4,5,6-pentafluorobenzyl methacrylate) (pPFBMA)\ud homopolymers with degrees of polymerization from 28 to 132 and Ð ≤ 1.29 was prepared by the\ud RAFT process. pPFBMA samples were atactic (with triad tacticity apparent in 1H and 19F NMR\ud spectra) and soluble in most organic solvents. pPFBMA reacted quantitatively through parafluoro\ud substitution with a range of thiols (typically 1.1 equiv thiol, base, RT, < 1h) in the absence\ud of any observed side reactions. Para-fluoro substitution with different (thio)carbonylthio\ud reagents was possible and allowed for subsequent one-pot cleavage of dithioester pendent groups\ud with concurrent thia-Michael side group modification. Reactions with aliphatic amines (typically\ud 2.5 equiv amine, 50–60 °C, overnight) resulted in complete substitution of the para-fluorides\ud without any observed ester cleavage reactions. However, for primary amines, H2NR, double\ud substitution reactions yielding tertiary (–C6F4)2NR amine bridges were observed, which were\ud absent with secondary amine reagents. No reactions were found for attempted modifications of\ud pPFBMA with bromide, iodide, methanethiosulfonate, or thiourea, indicating a highly selective\ud reactivity toward nucleophiles. The versatility of this reactive platform is demonstrated through\ud the synthesis of a pH-responsive polymer and novel thermoresponsive polymers: an\ud oligo(ethylene glycol)-functional species with an LCST in water and two zwitterionic polymers\ud with UCSTs in water and aqueous salt solution (NaCl concentration up to 178 mM)

The use of 2,3,4,5,6-pentafluorobenzyl methacrylate (PFBMA) as a core-forming monomer in ethanolic reversible addition-fragmentation chain transfer dispersion polymerization formulations is presented. Poly[poly(ethylene glycol) methyl ether methacrylate] (pPEGMA) macromolecular chain transfer agents were chain-extended with PFBMA leading to nanoparticle formation via polymerization-induced self-assembly (PISA). pPEGMA-pPFBMA particles exhibited the full range of morphologies (spheres, worms, and vesicles), including pure and mixed phases. Worm phases formed gels that underwent a thermo-reversible degelation and morphological transition to spheres (or spheres and vesicles) upon heating. Postsynthesis, the pPFBMA cores were modified through thiol-para-fluoro substitution reactions in ethanol using 1,8-diazabicyclo[5.4.0]undec-7-ene as the base. For monothiols, conversions were 64% (1-octanethiol) and 94% (benzyl mercaptan). Spherical and worm-shaped nano-objects were core cross-linked using 1,8-octanedithiol, which prevented their dissociation in nonselective solvents. For a temperature-responsive worm sample, cross-linking additionally resulted in the loss of the temperature-triggered morphological transition. The use of the reactive monomer PFBMA in PISA formulations presents a simple method to prepare well-defined nano-objects similar to those produced with nonreactive monomers (e.g., benzyl methacrylate) and to retain morphologies independent of solvent and temperature.

A novel monomer, 4-azido-2,3,5,6-tetrafluorobenzyl methacrylate (ABMA), enabled the selective and efficient postpolymerization modification of reversible addition–fragmentation chain transfer­(RAFT)-made homopolymers and diblock copolymer nanoparticles prepared through polymerization-induced self-assembly (PISA). Poly­(ABMA) homopolymers were modified postpolymerization in (near-)­quantitative conversions with phosphines to give stable iminophosphoranes and in a multicomponent reaction with phenylacetaldehyde and morpholine, piperidine, or the cross-linker N,N′-dimethylethylene diamine to give the corresponding amidine derivatives in one step. Product polymers were characterized by nuclear magnetic resonance and Fourier-transform infrared spectroscopy, size-exclusion chromatography, and differential scanning calorimetry. Unlike its monomer, poly­(ABMA) was insoluble in ethanol and enabled the preparation of well-defined spherical, worm-shaped, and vesicular nanoparticles with azide-functional cores through RAFT dispersion polymerization with concurrent PISA. The worm-shaped particles formed physical gels that underwent a thermally reversible degelation. Multicomponent modification of spherical nanoparticles with phenyl acetaldehyde and morpholine or piperidine led to (near-)­quantitative core modification and for morpholine, a significant increase in its sphere diameter. UV irradiation of nanoparticles led to cross-linking through the formation of reactive nitrene intermediates, which prevented the disassembly of nanoparticles in nonselective solvents, representing a simple and reagent-free cross-linking strategy and expanding the scope of azide-based polymer chemistry.

Spherical diblock copolymer nanoparticles became larger spheres, unimers, or worm-shaped particles when functionalised via thiol–para-fluoro substitution in the core.

In this work, we synthesize a polydisperse aqueous colloidal system composed of small and large zwitterionic particles, as well as medium sized standard acrylic particles. By assembling these dispersions into...