Synthesis of block polymers by homogeneous anionic polymerization

Fetters, Lewis J.

doi:10.1002/polc.5070260103

Cited by 87 publications

(11 citation statements)

References 118 publications

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“…The polymerization of isoprene monomer was carried out at 40°C for 3 h. The purified styrene monomer was then added, and the reaction was allowed to proceed for another 3 h. The ratios of monomer to initiator were varied to produce four different molecular weights of the diblock copolymers. This was done on the basis of traditional anionic living polymerization 16. Methanol was used as a terminating agent and nonsolvent for the copolymer.…”

Section: Methodsmentioning

confidence: 99%

Fluorescent Hydroxylamine Derived from the Fragmentation of PAMAM Dendrimers for Intracellular Hypochlorite Recognition

Liu

Chien

et al. 2013

Chemistry A European J

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Herein, a promising sensing approach based on the structure fragmentation of poly(amidoamine) (PAMAM) dendrimers for the selective detection of intracellular hypochlorite (OCl(-)) is reported. PAMAM dendrimers were easily disrupted by a cascade of oxidations in the tertiary amines of the dendritic core to produce an unsaturated hydroxylamine with blue fluorescence. Specially, the novel fluorophore was only sensitive to OCl(-), one of reactive oxygen species (ROS), resulting in an irreversible fluorescence turn-off. The fluorescent hydroxylamine was selectively oxidised by OCl(-) to form a labile oxoammonium cation that underwent further degradation. Without using any troublesomely synthetic steps, the novel sensing platform based on the fragmentation of PAMAM dendrimers, can be applied to detect OCl(-) in macrophage cells. The results suggest that the sensing approach may be useful for the detection of intracellular OCl(-) with minimal interference from biological matrixes.

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Section: Methodsmentioning

confidence: 99%

Fluorescent Hydroxylamine Derived from the Fragmentation of PAMAM Dendrimers for Intracellular Hypochlorite Recognition

Liu

Chien

et al. 2013

Chemistry A European J

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“…Two different triblock copolymers of SAS were synthesized by anionic polymerization.13~ 14 The compositions of the resulting polymers were determined by nuclear magnetic resonance spectroscopy. Molecular weights of these polymers were determined by gel permeation chromatograph.…”

Section: Experimental Methodsmentioning

confidence: 99%

Viscoelastic relaxation times of a homogeneous block copolymer

Shen

Hansen

1974

J. polym. sci., C Polym. symp.

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The molecular theory of viscoelasticity has been modified in a previous publication for homogeneous block copolymers; the theory predicts that the maximum relaxation time of the block copolymer can be computed with the knowledge of submolecular sizes and monomeric friction coefficients. Stress‐relaxation experiments were carried out for two samples of styrene‐(α‐methyl styrene)‐styrene triblock copolymers. Maximum relaxation times were determined from the viscoelastic master curve through the use of procedure X developed by Tobolksy and Murakami. Experimental results were found to be in reasonable agreement with theoretical predictions. The theory also predicts the existence of a singularity in the distribution of relaxation times at very short relaxation times, but as is discussed, this prediction cannot be verified by existing experimental techniques.

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“…This can only be achieved by controlling the molecular weight and architecture of the individual blocks through 'living' polymerizations. Cationic and anionic polymerizations have long been used to create well-defined blocks and architectures [68][69][70]. With the development of ring-opening metathesis polymerization (ROMP) [71,72] and the 'living' free radical polymerizations [73][74][75], a wider variety of polymer chemistries could be utilized.…”

Section: Block Copolymersmentioning

confidence: 99%