Synthesis and Study of Thermoresponsive Amphiphilic Copolymers via RAFT Polymerization

Synthesis and study of well-defined thermoresponsive amphiphilic copolymers with various compositions were reported. Kinetics of the reversible addition-fragmentation chain transfer (RAFT) (co)polymerization of styrene (St) and oligo(ethylene glycol) methyl ether methacrylate (PEO5MEMA) was studied by size exclusion chromatography (SEC) and 1H NMR spectroscopy, which allows calculating not only (co)polymerization parameters but also gives valuable information on RAFT (co)polymerization kinetics, process control, and chain propagation. Molecular weight Mn and dispersity Đ of the copolymers were determined by SEC with triple detection. The detailed investigation of styrene and PEO5MEMA (co)polymerization showed that both monomers prefer cross-polymerization due to their low reactivity ratios (r1 < 1, r2 < 1); therefore, the distribution of monomeric units across the copolymer chain of p(St-co-PEO5MEMA) with various compositions is almost ideally statistical or azeotropic. The thermoresponsive properties of p(St-co-PEO5MEMA) copolymers in aqueous solutions as a function of different hydrophilic/hydrophobic substituent ratios were evaluated by measuring the changes in hydrodynamic parameters under applied temperature using the dynamic light scattering method (DLS).

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Reversible Addition Fragmentation Chain Transfer (RAFT) Polymerization of Methyl Acrylate: Detailed Structural Investigation via Coupled Size Exclusion Chromatography−Electrospray Ionization Mass Spectrometry (SEC−ESI-MS)

Macromolecules ◽

10.1021/ma035244t ◽

2004 ◽

Vol 37 (3) ◽

pp. 744-751 ◽

Cited By ~ 85

Author(s):

Andrew Ah Toy ◽

Philipp Vana ◽

Thomas P. Davis ◽

Christopher Barner-Kowollik

Keyword(s):

Mass Spectrometry ◽

Electrospray Ionization ◽

Methyl Acrylate ◽

Structural Investigation ◽

Chain Transfer ◽

Raft Polymerization ◽

Size Exclusion ◽

Ionization Mass ◽

Reversible Addition ◽

Exclusion Chromatography

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Nano-Assemblies from Amphiphilic PnBA-b-POEGA Copolymers as Drug Nanocarriers

Polymers ◽

10.3390/polym13071164 ◽

2021 ◽

Vol 13 (7) ◽

pp. 1164

Author(s):

Angeliki Chroni ◽

Thomas Mavromoustakos ◽

Stergios Pispas

Keyword(s):

Molecular Weight ◽

Chain Transfer ◽

Raft Polymerization ◽

Polymeric Nanocarriers ◽

Reversible Addition ◽

2D Noesy ◽

Drug Nanocarriers ◽

Glycol Methyl Ether ◽

Different Molecular Weight

The focus of this study is the development of highly stable losartan potassium (LSR) polymeric nanocarriers. Two novel amphiphilic poly(n-butyl acrylate)-block-poly(oligo(ethylene glycol) methyl ether acrylate) (PnBA-b-POEGA) copolymers with different molecular weight (Mw) of PnBA are synthesized via reversible addition fragmentation chain transfer (RAFT) polymerization, followed by the encapsulation of LSR into both PnBA-b-POEGA micelles. Based on dynamic light scattering (DLS), the PnBA30-b-POEGA70 and PnBA27-b-POEGA73 (where the subscripts denote wt.% composition of the components) copolymers formed micelles of 10 nm and 24 nm in water. The LSR-loaded PnBA-b-POEGA nanocarriers presented increased size and greater mass nanostructures compared to empty micelles, implying the successful loading of LSR into the inner hydrophobic domains. A thorough NMR (nuclear magnetic resonance) characterization of the LSR-loaded PnBA-b-POEGA nanocarriers was conducted. Strong intermolecular interactions between the biphenyl ring and the butyl chain of LSR with the methylene signals of PnBA were evidenced by 2D-NOESY experiments. The highest hydrophobicity of the PnBA27-b-POEGA73 micelles contributed to an efficient encapsulation of LSR into the micelles exhibiting a greater value of %EE compared to PnBA30-b-POEGA70 + 50% LSR nanocarriers. Ultrasound release profiles of LSR signified that a great amount of the encapsulated LSR is strongly attached to both PnBA30-b-POEGA70 and PnBA27-b-POEGA73 micelles.

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Molecular Weight and Tacticity of Oligoacrylates by Capillary Electrophoresis - Mass Spectrometry

Australian Journal of Chemistry ◽

10.1071/ch10088 ◽

2010 ◽

Vol 63 (8) ◽

pp. 1219 ◽

Cited By ~ 17

Author(s):

Marianne Gaborieau ◽

Tim J. Causon ◽

Yohann Guillaneuf ◽

Emily F. Hilder ◽

Patrice Castignolles

Keyword(s):

Capillary Electrophoresis ◽

Raft Polymerization ◽

Degree Of Polymerization ◽

Size Exclusion ◽

Separation Mechanism ◽

Ionization Mass ◽

Polymeric Particles ◽

Reversible Addition ◽

Exclusion Chromatography

Oligo(acrylic acid) efficiently stabilizes polymeric particles, especially particles produced by reversible addition–fragmentation chain transfer (RAFT) (as hydrophilic block of an amphiphilic copolymer). Capillary electrophoresis (CE) has a far higher resolution power to separate these oligomers than the commonly used size exclusion chromatography. Coupling CE to electrospray ionization mass spectrometric detection unravels the separation mechanism. CE separates these oligomers, not only according to their degree of polymerization, but also according to their tacticity, in agreement with NMR analysis. Such analysis will provide insight into the role of these oligomers as stabilizers in emulsion polymerization, and into the mechanism of the RAFT polymerization with respect to degree of polymerization and tacticity.

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Kinetics of RAFT polymerization and copolymerization of vinyl monomers by size exclusion chromatography

European Polymer Journal ◽

10.1016/j.eurpolymj.2019.109356 ◽

2020 ◽

Vol 122 ◽

pp. 109356 ◽

Cited By ~ 4

Author(s):

Vaidas Klimkevicius ◽

Medeina Steponaviciute ◽

Ricardas Makuska

Keyword(s):

Size Exclusion Chromatography ◽

Raft Polymerization ◽

Size Exclusion ◽

Vinyl Monomers ◽

Exclusion Chromatography ◽

Kinetics Of

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Reversing RAFT Polymerization: Near-Quantitative Monomer Generation via a Catalyst-Free Depolymerization Approach

10.33774/chemrxiv-2021-5bqz9 ◽

2021 ◽

Author(s):

Hyun Suk Wang ◽

Nghia P. Truong ◽

Athina Anastasaki

Keyword(s):

Chain Transfer ◽

Raft Polymerization ◽

Controlled Radical Polymerization ◽

Catalyst Free ◽

Reversible Addition ◽

Fundamental Research ◽

New Applications ◽

Raft Polymers ◽

Glycol Methyl Ether ◽

End Group

The ability to reverse controlled radical polymerization and regenerate the monomer would be highly beneficial for both fundamental research and applications, yet has remained very challenging to achieve. Herein, we report a near-quantitative (up to 92%) and catalyst-free depolymerization of various linear, bulky, crosslinked, and functional polymethacrylates made by reversible addition-fragmentation chain-transfer (RAFT) polymerization. Key to our approach is to exploit the high end-group fidelity of RAFT polymers to generate chain-end radicals via thermal homolytic cleavage of carbon-sulfur bond of the RAFT end-group at 120 °C. These radicals trigger a rapid unzipping of both conventional (e.g. poly(methyl methacrylate)) and bulky polymers (e.g. poly(oligo(ethylene glycol) methyl ether methacrylate) (POEGMA)). Importantly, the depolymerization product can be utilized to either reconstruct the linear polymer or create an entirely new insoluble gel that can also be subjected to depolymerization. This work expands the potential of polymers made by CRP, pushes the boundaries of depolymerization, offers intriguing mechanistic aspects, and enables new applications.

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A Novel One-Pot Procedure for the Fast and Efficient Conversion of RAFT Polymers into Hydroxy-Functional Polymers

Australian Journal of Chemistry ◽

10.1071/ch09080 ◽

2009 ◽

Vol 62 (8) ◽

pp. 806 ◽

Cited By ~ 34

Author(s):

Till Gruendling ◽

Mathias Dietrich ◽

Christopher Barner-Kowollik

Keyword(s):

Elevated Temperatures ◽

Raft Polymerization ◽

Functional Polymers ◽

Size Exclusion ◽

One Pot ◽

Reversible Addition ◽

Exclusion Chromatography ◽

Azo Initiator ◽

Raft Polymers ◽

End Group

We report on the successful quantitative transformation of methacrylate and acrylate-type polymers prepared by reversible addition–fragmentation chain transfer (RAFT) polymerization carrying a dithioester-end-group into hydroxy-functional polymers. The simple reaction procedure involves stirring a solution of the dithioester-capped polymer and an azo-initiator in tetrahydrofuran at elevated temperatures (T = 60°C) in the presence of air. This reaction quantitatively yields hydroperoxide functionalities that can be efficiently reduced to hydroxy groups in a one-pot procedure using triphenylphosphine. Size exclusion chromatography–electrospray mass spectrometry was employed to monitor the progress of the reaction. The new backbone-linked hydroxy group provides a versatile anchor for chemical end-group conversions and conjugation reactions with prepared RAFT polymers, which alleviates problems with the rather limited ability of the dithioester-end-group to undergo non-radical transformations.

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Dendrimers as Scaffolds for Reversible Addition Fragmentation Chain Transfer (RAFT) Agents: a Route to Star-Shaped Block Copolymers

Australian Journal of Chemistry ◽

10.1071/ch05036 ◽

2005 ◽

Vol 58 (6) ◽

pp. 483 ◽

Cited By ~ 26

Author(s):

Xiaojuan Hao ◽

Eva Malmström ◽

Thomas P. Davis ◽

Martina H. Stenzel ◽

Christopher Barner-Kowollik

Keyword(s):

Molecular Weight ◽

Block Copolymers ◽

Butyl Acrylate ◽

Chain Transfer ◽

Raft Polymerization ◽

Star Polymers ◽

Size Exclusion ◽

Chain Extension ◽

Reversible Addition ◽

Star Block Copolymers

Star-shaped block copolymers of styrene and n-butyl acrylate having three, six, and twelve pendent arms were successfully synthesized via reversible addition fragmentation chain transfer (RAFT) polymerization. Dendritic cores (based on 1,1,1-trimethylolpropane) of generation 0, 1, and 2 have been functionalized with 3-benzylsulfanylthiocarbonylsulfanylpropionic ester groups and have subsequently been employed to mediate the polymerization of styrene and n-butyl acrylate to generate macro-star-RAFT agents as starting materials for chain extension. The chain extension of the macro-star-RAFT agents with either styrene or n-butyl acrylate by bulk free radical polymerization at 60°C gives narrowly distributed polymer (final polydispersities close to 1.2) increasing linearly in molecular weight with increasing monomer-to-polymer conversion. However, with an increasing number of arms (i.e., when going from three- to twelve-armed star polymers), the chain extension becomes significantly less efficient. The molecular weight of the generated block copolymers was assessed using 1H NMR spectroscopy as well as size exclusion chromatography calibrated with linear polystyrene standards. The hydrodynamic radius, Rh, of the star block copolymers as well as the precursor star polymers was determined in tetrahydrofuran by dynamic light scattering (90°) at 25°C. Interestingly, the observed Rh–Mn relationships indicate a stronger dependence of Rh on Mn for poly(butyl acrylate) stars than for the corresponding styrene polymers. Rh increases significantly when the macro-star-RAFT agent is chain extended with either styrene or n-butyl acrylate.

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Self-Healing Hydrophobic POSS-functionalized Fluorinated Copolymer via RAFT Polymerization and dynamic Diels-Alder Reaction

Polymer Chemistry ◽

10.1039/d0py01522a ◽

2021 ◽

Author(s):

Siva Ponnupandian ◽

Prantik Mondal ◽

Thomas Becker ◽

Richard Hoogenboom ◽

Andrew B Lowe ◽

...

Keyword(s):

Chain Transfer ◽

Raft Polymerization ◽

Alder Reaction ◽

Diels Alder ◽

Self Healing ◽

Diels Alder Reaction ◽

Reversible Addition

This investigation reports the preparation of a tailor-made copolymer of furfuryl methacrylate (FMA) and trifluoroethyl methacrylate (TFEMA) via reversible addition-fragmentation chain transfer (RAFT) polymerization. The furfuryl groups of the copolymer...

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Synthesis and characterization of a naphthalimide–dye end-labeled copolymer by reversible addition–fragmentation chain transfer (RAFT) polymerization

Canadian Journal of Chemistry ◽

10.1139/v10-134 ◽

2011 ◽

Vol 89 (3) ◽

pp. 317-325 ◽

Cited By ~ 10

Author(s):

Binxin Li ◽

Daniel Majonis ◽

Peng Liu ◽

Mitchell A. Winnik

Keyword(s):

Chain Transfer ◽

Raft Polymerization ◽

Polymer Composition ◽

Cooh Group ◽

Agent Based ◽

Molecular Weights ◽

Reversible Addition ◽

Raft Agent ◽

End Use ◽

Naphthalimide Dye

We describe the synthesis of an end-functionalized copolymer of N-(2-hydroxypropyl)methacrylamide (HPMA) and N-hydroxysuccinimide methacrylate (NMS) by reversible addition–fragmentation chain transfer (RAFT) polymerization. To control the polymer composition, the faster reacting monomer (NMS) was added slowly to the reaction mixture beginning 30 min after initating the polymerization (ca. 16% HPMA conversion). One RAFT agent, based on azocyanopentanoic acid, introduced a –COOH group to the chain at one end. Use of a different RAFT agent containing a 4-amino-1,8-naphthalimide dye introduced a UV–vis absorbing and fluorescent group at this chain end. The polymers obtained had molecular weights of 30 000 and 20 000, respectively, and contained about 30 mol% NMS active ester groups.

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