PhotoATRP-Induced Self-Assembly (PhotoATR-PISA) Enables Simplified Synthesis of Responsive Polymer Nanoparticles in One-Pot (original) (raw)
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Photoinitiated Polymerization-Induced Self-Assembly (Photo-PISA): New Insights and Opportunities
Advanced science (Weinheim, Baden-Wurttemberg, Germany), 2017
The polymerization-induced self-assembly (PISA) process is a useful synthetic tool for the efficient synthesis of polymeric nanoparticles of different morphologies. Recently, studies on visible light initiated PISA processes have offered a number of key research opportunities that are not readily accessible using traditional thermally initiated systems. For example, visible light mediated PISA (Photo-PISA) enables a high degree of control over the dispersion polymerization process by manipulation of the wavelength and intensity of incident light. In some cases, the final nanoparticle morphology of a single formulation can be modulated by simple manipulation of these externally controlled parameters. In addition, temporal (and in principle spatial) control over the Photo-PISA process can be achieved in most cases. Exploitation of the mild room temperature polymerizations conditions can enable the encapsulation of thermally sensitive therapeutics to occur without compromising the poly...
ACS Macro Letters, 2017
In this communication, we investigate the photoinduced electron/energy transfer−reversible addition− fragmentation chain transfer (PET-RAFT) polymerization of 2-(methylthio)ethyl methacrylate (MTEMA) using 5,10,15,20tetraphenylporphine zinc (ZnTPP) as a photocatalyst under visible red light (λ max = 635 nm). Interestingly, the polymerization kinetics were not affected by the presence of air as near identical polymerization kinetics were observed for nondeoxygenated and deoxygenated systems, which is attributed to the singlet oxygen quenching ability of MTEMA. In both cases, well-defined polymers were obtained with good control over the molecular weight and molecular weight distribution (MWD). Furthermore, we have demonstrated that MTEMA can undergo the polymerization-induced self-assembly (PISA) process from a poly(oligo(ethylene glycol) methyl ether methacrylate) (POEGMA) macromolecular chain transfer agent (macro-CTA) to yield well-defined polymeric nanoparticles of various morphologies. These nanoparticles were rapidly disassembled after exposure to visible light due to the formation of singlet oxygen by the encapsulated ZnTPP and subsequent rapid oxidation of the thioether group.
Journal of the American Chemical Society, 2015
Nature has developed efficient polymerization processes, which allow the synthesis of complex macromolecules with a perfect control of tacticity as well as molecular weight, in response to a specific stimulus. In this contribution, we report the synthesis of various stereopolymers by combining a photoactivated living polymerization, named photoinduced electron transfer−reversible addition−fragmentation chain transfer (PET-RAFT) with Lewis acid mediators. We initially investigated the tolerance of two different photoredox catalysts, i.e., Ir(ppy) 3 and Ru(bpy) 3 , in the presence of a Lewis acid, i.e., Y(OTf) 3 and Yb(OTf) 3 , to mediate the polymerization of N,N-dimethyl acrylamide (DMAA). An excellent control of tacticity as well as molecular weight and dispersity was observed when Ir(ppy) 3 and Y(OTf) 3 were employed in a methanol/toluene mixture, while no polymerization or poor control was observed with Ru(bpy) 3. In comparison to a thermal system, a lower amount of Y(OTf) 3 was required to achieve good control over the tacticity. Taking advantage of the temporal control inherent in our system, we were able to design complex macromolecular architectures, such as atactic block-isotactic and isotactic-block-atactic polymers in a one-pot polymerization approach. Furthermore, we discovered that we could modulate the degree of tacticity through a chemical stimulus, by varying [DMSO] 0 /[Y(OTf) 3 ] 0 ratio from 0 to 30 during the polymerization. The stereochemical control afforded by the addition of a low amount of DMSO in conjunction with the inherent temporal control enabled the synthesis of stereogradient polymer consisting of five different stereoblocks in one-pot polymerization.
Visible Light-Mediated Polymerization-Induced Self-Assembly Using Continuous Flow Reactors
Macromolecules, 2018
We report the use of visible light to mediate a RAFT dispersion polymerization in the absence of external catalyst or initiator to yield nanoparticles of different morphologies according to a polymerization-induced selfassembly (PISA) mechanism. A POEGMA macro-chain transfer agent (macro-CTA) derived from a 4-cyano-4-((dodecylsulfanylthiocarbonyl)sulfanyl)pentanoic acid (CDTPA) RAFT agent can be activated under blue (460 nm, 0.7 mW/cm 2) or green (530 nm, 0.7 mW/cm 2) light and act simultaneously as a radical initiator, chain transfer agent, and particle stabilizer under ethanolic dispersion conditions. In particular, the formation of worm-like micelles was readily monitored by the increase of reaction viscosity during the polymerization; this method was shown to be particularly robust to different reaction parameters such as macro-CTAs of varying molecular weight. Interestingly, at high monomer conversion, different morphologies were formed depending on the wavelength of light employed, which may be due to differing degrees of polymerization control. Finally, the in situ encapsulation of the model hydrophobic drug, Nile Red, was demonstrated, suggesting applications of this facile process for the synthesis of nanoparticles for drug delivery applications.
Polymer Chemistry
Well-defined poly(methyl methacrylate) was prepared by a photochemically induced reversible deactivation radical polymerization using 50−200 ppm of copper catalyst in dimethyl sulfoxide under both an inert atmosphere and in the presence of limited amount of air. Effect of the ligand structure and concentration on kinetics and polymerization control was investigated. Under inert atmosphere, equimolar amount of the ligand, such as tris(2-pyridylmethyl)amine (TPMA) or N,N,N’,N’’,N’’-pentamethyldiethylenetriamine (PMDETA), was sufficient to achieve well-controlled polymerization of MMA. In the presence of air, a well-controlled polymerization started just after some induction time, which was dependent on the concentration of TPMA ligand. Irradiation at λ > 350 nm provided both a photochemical reduction of an initially-added copper(II) catalyst, which complexed with either PMDETA or TPMA ligand, to a copper(I) activator, and photochemical regeneration of the copper(I) activator after ...
Journal of Polymer Science Part A-polymer Chemistry, 2005
␣,-Di(iodo)poly(vinyl chloride)s, with number-average molecular weights ranging from 2100 to 29,500 and molecular weight distributions (weight-average molecular weight/number-average molecular weight) ranging from 1.74 to 2.16, were prepared by the previously reported single-electron-transfer/degenerative-chain-transfer mediated living radical polymerization of vinyl chloride initiated with iodoform and catalyzed by sodium dithionite in water at 25-35°C. These ␣,-di(iodo)poly(vinyl chloride) macroinitiators were used for the synthesis of poly(methyl methacrylate)-bpoly(vinyl chloride)-b-poly(methyl methacrylate) (PMMA-b-PVC-b-PMMA) block copolymers via the metal-catalyzed living radical block copolymerization of methyl methacrylate. In this article, we report the effects of various ligands on the rate of block copolymerization mediated by Cu(0) in dimethyl sulfoxide (DMSO). The block copolymerization catalyzed by Cu(0)/tris(2-dimethylaminoethyl)amine in DMSO at 90°C yielded block copolymers in less than 15 min, whereas at 25°C, the reaction times ranged from 60 to 100 min. Therefore, this ultrafast synthetic method provided access to PMMA-b-PVC-b-PMMA, regardless of the reaction temperature, in the same range of reaction times as the induction period of the same reactions carried out at 90°C in diphenyl ether and catalyzed by CuCl/2,2Ј-bipyridine.
Macromolecular rapid communications, 2011
A rare self-assembly behavior is observed in a hydrophilic monomer (4-vinylpyridine) (4VP) when polymerized in water with a hydrophilic initiator that results in the production of monodisperse polymeric nanoparticles in a single step. This behavior mimics the behavior obtained with the more commonly reported amphiphilic block copolymers. The synthesis and self-assembly of homopolymer nanoparticle from 4VP without the use of any crosslinker, stabilizing agent, surfactant, or polymeric emulsifier are described along with fundamental aspects of the mechanism of this polymerization. This facile and robust procedure enabled the production of highly monodisperse P4VP nanoparticle with a tunable size ranging from 80 to 445 nm. For the first time, we have investigated the growth mechanism of these polymeric nanoparticles to clarify the mechanism of polymeric nanoparticle formation. This work also provides direct visible evidence through transmission electron microscopy (TEM) images at the nanometer scale, which helps in obtaining a better understanding of the mechanism of self-assembly. The effect of temperature on the size of the polymeric nanoparticles was also examined along with the effect of initiator, monomer, and solvent concentrations. We therefore report a versatile and scalable process for the production of monodisperse polymeric nanoparticles, which we call self-emulsion polymerization (SEP).