scholarly journals RAFT Synthesis and Self-Assembly of Free-Base Porphyrin Cored Star Polymers

2011 ◽  
Vol 2011 ◽  
pp. 1-11 ◽  
Author(s):  
Lin Wu ◽  
Ronan McHale ◽  
Guoqiang Feng ◽  
Xiaosong Wang
Keyword(s):  
Block Copolymers ◽  
Self Assembly ◽  
Chain Transfer ◽  
Star Polymers ◽  
Free Base ◽  
Molecular Weights ◽  
Material Development ◽  
Reversible Addition ◽  
Spectrophotometric Titrations ◽  
Star Block Copolymers

Reversible addition fragmentation chain transfer (RAFT) synthesis and self-assembly of free-base porphyrin cored star polymers are reported. The polymerization, in the presence of a free-base porphyrin cored chain transfer agent (CTA-FBP), produced porphyrin star polymers with controlled molecular weights and narrow polydispersities for a number of monomers includingN,N-dimethylacrylamide (DMA) and styrene (St). Well-defined amphiphilic star block copolymers, P-(PS-PDMA)4and P-(PDMA-PS)4(P: porphyrin), were also prepared and used for self-assembly studies. In methanol, a selective solvent for PDMA, spherical micelles were observed for both block copolymers as characterized by TEM. UV-vis studies suggested star-like micelles were formed from P-(PS-PDMA)4, while P-(PDMA-PS)4aggregated into flower-like micelles. Spectrophotometric titrations indicated that the optical response of these two micelles to external ions was a function of micellar structures. These structure-related properties will be used for micelle studies and functional material development in the future.

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

2005 ◽  
Vol 58 (6) ◽  
pp. 483 ◽  
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.

Synthesis of Polystyrene-B-Poly(Ethylene Oxide)monomethyl Ethermethacrylate Block Copolymers and its Self-Assembly in Aqueous Solution

2011 ◽  
Vol 284-286 ◽  
pp. 769-772
Author(s):  
Qian Qian You ◽  
Pu Yu Zhang
Keyword(s):  
Aqueous Solution ◽  
Molecular Weight ◽  
Block Copolymers ◽  
Self Assembly ◽  
Chain Transfer ◽  
Functional Group ◽  
Transmission Electron ◽  
Reversible Addition ◽  
Ft Ir ◽  
A Chain

The block copolymer of PSt-b-POEOMA with the end of -COOH functional group has been synthesized by reversible addition fragmentation chain-transfer (RAFT) using S,S′-Bis(α,α′-dimethyl-α′′-acetic acid)-trithiocarbonate (BDATC) as a chain transfer agent. The architectures of the copolymers were confirmed by FT-IR and 1HNMR spectra. GPC analysis was used to estimate the molecular weight and the molecular weight distribution of the copolymers. Meanwhile, The nanostructures of the block copolymers PSt-b-POEOMA micelles formed in aqueous solution were observed by transmission electron microscopy (TEM) and dynamic light scattering (DLS).

scholarly journals Synthesis of Poly(3-vinylpyridine)-Block-Polystyrene Diblock Copolymers via Surfactant-Free RAFT Emulsion Polymerization

Materials ◽  
2019 ◽  
Vol 12 (19) ◽  
pp. 3145 ◽  
Author(s):  
Katharina Nieswandt ◽  
Prokopios Georgopanos ◽  
Clarissa Abetz ◽  
Volkan Filiz ◽  
Volker Abetz
Keyword(s):  
Emulsion Polymerization ◽  
Self Assembly ◽  
Diblock Copolymers ◽  
Chain Transfer ◽  
Raft Polymerization ◽  
Free Water ◽  
Monomer Conversion ◽  
Molecular Weights ◽  
Reversible Addition

In this work, we present a novel synthetic route to diblock copolymers based on styrene and 3-vinylpyridine monomers. Surfactant-free water-based reversible addition–fragmentation chain transfer (RAFT) emulsion polymerization of styrene in the presence of the macroRAFT agent poly(3-vinylpyridine) (P3VP) is used to synthesize diblock copolymers with molecular weights of around 60 kDa. The proposed mechanism for the poly(3-vinylpyridine)-block-poly(styrene) (P3VP-b-PS) synthesis is the polymerization-induced self-assembly (PISA) which involves the in situ formation of well-defined micellar nanoscale objects consisting of a PS core and a stabilizing P3VP macroRAFT agent corona. The presented approach shows a well-controlled RAFT polymerization, allowing for the synthesis of diblock copolymers with high monomer conversion. The obtained diblock copolymers display microphase-separated structures according to their composition.

Synthesis of Cationic Amphiphilic Block Copolymers Poly(4-vinylbenzyltriethylammonium chloride)-b-Poly(styrene) and Their Self-Assembly in Aqueous Solution

2016 ◽  
Vol 16 (4) ◽  
pp. 4239-4246
Author(s):  
Zhijiao Dong ◽  
Bingbing Yang ◽  
Zhifeng Fu ◽  
Yan Shi
Keyword(s):  
Block Copolymers ◽  
Formation Process ◽  
Self Assembly ◽  
Chain Transfer ◽  
Amphiphilic Block Copolymers ◽  
The Core ◽  
Reversible Addition ◽  
The Common ◽  
Spherical Micelles ◽  
Large Compound

Well defined two kinds of cationic amphiphilic block copolymers Poly(4-vinylbenzyltriethylammonium chloride)-b-Poly(styrene) are synthesized by combining reversible addition fragmentation chain transfer polymerizations and post-polymerization quaternization. Block copolymers are characterized by GPC and 1HNMR. The self-assembly behaviors of the block copolymers are studied, which are characterized by TEM. For Poly(4-vinylbenzyltriethylammonium chloride)13-b-Poly(styrene)136, crew-cut spherical micelles are obtained by using DMF as the initial common solvent, and the majority of the pearl series aggregates and a small amount of rod-like aggregates are all observed by using the mixture of DMF and THF as the initial common solvent. The formation process of rod-like aggregates is proposed in three steps: the micellization of copolymer chains, the formation of pearl series aggregates from the collision and fusion of individual initial spherical micelles, and the transformation from pearl series aggregates to rod-like aggregates. For Poly(4- vinylbenzyltriethylammonium chloride)18-b-Poly(styrene)370, large compound micelles and complicated spherical aggregates and small vesicles are all obtained. The formation process of small vesicles is also proposed in three steps: the formation of initial spherical micelles with some hydrophilic block Poly(4-vinylbenzyltriethylammonium chloride) embedded in the core, the removing of the outer layer common solvent, and solvent nucleation in the center. It should be noted that solvent nucleation is critical, because of the hydrophilic block Poly(4-vinylbenzyltriethylammonium chloride) and the common solvent and water embedded in the core of the initial spherical micelles.

scholarly journals Synthesis of Terpyridine-Terminated Amphiphilic Block Copolymers and Their Self-Assembly into Metallo-Polymer Nanovesicles

Materials ◽  
2019 ◽  
Vol 12 (4) ◽  
pp. 601 ◽  
Author(s):  
Tatyana Elkin ◽  
Stacy Copp ◽  
Ryan Hamblin ◽  
Jennifer Martinez ◽  
Gabriel Montaño ◽  
...  
Keyword(s):  
Polyethylene Glycol ◽  
Block Copolymers ◽  
Self Assembly ◽  
Chain Transfer ◽  
Raft Polymerization ◽  
Amphiphilic Block Copolymers ◽  
Transmission Electron ◽  
Reversible Addition ◽  
Efficient Route ◽  
High Yields

Polystyrene-b-polyethylene glycol (PS-b-PEG) amphiphilic block copolymers featuring a terminal tridentate N,N,N-ligand (terpyridine) were synthesized for the first time through an efficient route. In this approach, telechelic chain-end modified polystyrenes were produced via reversible addition-fragmentation chain-transfer (RAFT) polymerization by using terpyridine trithiocarbonate as the chain-transfer agent, after which the hydrophilic polyethylene glycol (PEG) block was incorporated into the hydrophobic polystyrene (PS) block in high yields via a thiol-ene process. Following metal-coordination with Mn2+, Fe2+, Ni2+, and Zn2+, the resulting metallo-polymers were self-assembled into spherical, vesicular nanostructures, as characterized by dynamic light scattering and transmission electron microscopy (TEM) imaging.

Synthesis of N-vinylcarbazole–N-vinylpyrrolidone amphiphilic block copolymers by xanthate-mediated controlled radical polymerization

2010 ◽  
Vol 88 (3) ◽  
pp. 228-235 ◽  
Author(s):  
Chih-Feng Huang ◽  
Jeong Ae Yoon ◽  
Krzysztof Matyjaszewski
Keyword(s):  
Block Copolymers ◽  
Chain Transfer ◽  
Raft Polymerization ◽  
Controlled Radical Polymerization ◽  
Amphiphilic Block Copolymers ◽  
Force Microscopy ◽  
Molecular Weights ◽  
Atomic Force ◽  
Reversible Addition ◽  
Mode Atomic Force Microscopy

Amphiphilic block copolymers poly(N-vinylcarbazole)-b-poly(N-vinylpyrrolidone) (PNVK-b-PNVP) were prepared by xanthate-mediated reversible addition-fragmentation chain transfer (RAFT) polymerization. Both the PNVK and PNVP macroinitiators and the resulting block copolymers had molecular weights close to theoretical values, predicted for efficient initiation, in the range of Mn = 30 000 to 90 000. The block copolymers dissolved in several organic solvents but, depending on their composition, in methanol formed either micelles or large aggregates, as confirmed by dynamic light scattering. The presence of globular aggregates was confirmed by tapping mode atomic force microscopy.

Controlled RAFT synthesis of polystyrene-b-poly(acrylic acid)-b-polystyrene block copolymers and their self-assembly in an ionic liquid [BMIM][PF6]

e-Polymers ◽  
2011 ◽  
Vol 11 (1) ◽  
Author(s):  
Linping Zheng ◽  
Yun Chai ◽  
Yang Liu ◽  
Puyu Zhang
Keyword(s):  
Ionic Liquid ◽  
Block Copolymers ◽  
Self Assembly ◽  
Chain Transfer ◽  
Raft Polymerization ◽  
Amphiphilic Block Copolymers ◽  
Transmission Electron ◽  
Reversible Addition ◽  
Potential Applications ◽  
Increasing Temperature

AbstractThe block copolymer of polystyrene-block-polyacrylate-blockpolystyrene (PSt-PAA-PSt) has been synthesized by reversible addition fragmentation chain-transfer (RAFT) polymerization using S,S′-Bis(α,α′-dimethyl-α′′-acetic acid)-trithiocarbonate (BDATC) as chain transfer agent. Three copolymers form micelles in an ionic liquid, 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM][PF6]). The nanostructures of the PSt-PAA-PSt micelles formed in ionic liquid were observed by transmission electron microscopy (TEM). The self-assembled morphologies of the micelles are strongly dependent on the length of PAA block chains when the chain length of PS is fixed. The affinity of PAA chains for water and [BMIM][PF6] reverses with increasing temperature. Research results show that the copolymer with low polydispersity can be obtained by controlling polymerization, and the flexibility of amphiphilic block copolymers for controlling nanostructure in an ionic liquid presents potential applications in many arenas.

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