Block copolymers via thermal polymeric iniferters. Synthesis of silicone-vinyl block copolymers

Nair, C. P. Reghunadhan; Clouet, G.

doi:10.1021/ma00207a021

Cited by 39 publications

(18 citation statements)

References 5 publications

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“…The term 'iniferter' is used for free radical initiators with simultaneous chain transfer and terminating properties, thereby providing a pseudo-living polymerization (13)(14)(15)(16). This technique enabled us to synthesize a novel type of multiblock copolymer, consisting of alternating polybutadiene (PB) and (styrene-eo-acrylonitrile) (SAN) blocks (17,18), or alternating polybutadiene and (styrene-eo-maleic anhydride) (SMA) blocks (19).…”

Section: * Corresponding Authormentioning

confidence: 99%

Compatibilization of low-density polyethylene/polystyrene blends by segmented EB(PS-block-EB) n block copolymers

1997

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Summary Hydrogenatedsegmented poly [butadiene-block-(styrene-block-butadiene)n] block copolymers, which were developed by use of a polymeric iniferter technique, were tested on their compatibilizing effectiveness for (10/90) LDPE/PS blends. They were found to be effective compatibilizers for this mixture, already giving a pronounced improvement in both tensile strength and strain of the blend at block copolymer concentrations of one percent. A concentration of five weight percent of segmented block copolymer provided a tenfold improvement in blend toughness. The effectiveness of the segmented block copolymers was found be dependent on the block copolymer composition. Block copolymer compositions of close to 50:50 EB:PS gave the best results. IntroductionPolymer blends could provide materials having a wide variety of mechanical properties by adjusting the type and quantity of polymers in the mixture. However, because most polymers are immiscible, the blend components usually phase separate into macroscopic domains and consequently show poor mechanical properties, particularly regarding ductility. It is well known that block or graft copolymers, containing blocks of the same chemical structure as the hetero phases in an incompatible binary polymer blends, are capable of compatibilizing these polymer mixtures (1-4). When localized at the interface between the immiscible polymers, the block copolymers lower the interfacial tension, thereby dispersing the polymer blend into smaller domains due to reduced coalescence of the stabilized particles. Consequently, the blends may show improved ductility, because of enhanced force transfer between the different phases.Although the compatibilization of blends has been investigated extensively, the effect of compatibilizer architecture is still rather questionable. The number of blocks appear to playa significant role here. In various experimental studies quite different effects of the number of blocks in a block copolymer on its compatibilizing effectiveness have been reported. For example, in a paper by Teyssié et aI. diblock copolymers have been found to be more efficient compatibilizers than triblock copolymers (5), while in some other works quite the opposite effect is presented (6-8), and another one states that there is no difference in compatibilizing effectiveness between di-and triblock copolymers (9).

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Section: * Corresponding Authormentioning

confidence: 99%

Compatibilization of low-density polyethylene/polystyrene blends by segmented EB(PS-block-EB) n block copolymers

1997

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“…For example, PDMS containing internal tetraphenylethylene moieties was used for the synthesis of segmented multiblock copolymers with various vinyl monomers 21, 22. Although the use of macroinitiators for free radical polymerization appeared to be very promising, conventional methods introduced problems such as limited end‐group functionalization, incomplete initiation efficiency and homopolymer formation 23, 24…”

Section: Introductionmentioning

confidence: 99%

Atom transfer radical polymerization of styrene and methyl (meth)acrylates initiated with poly(dimethylsiloxane) macroinitiator: Synthesis and characterization of triblock copolymers

Semsarzadeh

Abdollahi

2011

J of Applied Polymer Sci

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Poly(dimethylsiloxane)(PDMS)-based triblock copolymers were successfully synthesized via atom transfer radical polymerization (ATRP) initiated with bis (bromoalkyl)-terminated PDMS macroinitiator (Br-PDMSBr). First, Br-PDMS-Br was prepared by reaction between the bis(hydroxyalkyl)-terminated PDMS and 2-bromo-2-methylpropionyl bromide. PSt-b-PDMS-b-PSt, PMMA-b-PDMS-b-PMMA and PMA-b-PDMS-b-PMA triblock copolymers were then synthesized via ATRP of styrene (St), methyl methacrylate (MMA) and methyl acrylate (MA), respectively, in the presence of Br-PDMS-Br as a macroinitiator and CuCl/PMDETA as a catalyst system at 80 o C. Triblock copolymers were characterized by FTIR, 1 H-NMR and GPC techniques. GPC results showed linear dependence of the number-average molecular weight on the conversion as well as the narrow polydispersity indicies (PDI < 1.57) for the synthesized triblock copolymers which was lower than that of Br-PDMS-Br macroinitiator (PDI ¼ 1.90), indicating the living/controlled characteristic of the reaction. Also, there was a very good agreement between the number-average molecular weight calculated from 1 HNMR spectra and that calculated theoretically. Results showed that resulting copolymers have two glass transition temperatures, indicating that triblock copolymers have microphase separated morphology.

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“…For example, PDMS containing internal tetraphenylethylene moieties was used for the synthesis of segmented multiblock copolymers with various vinyl monomers 9,10. While the use of macroinitiators for free radical polymerization appeared to be very promising, conventional methods introduced problems such as limited end‐group functionalization, incomplete initiation efficiency, and homopolymer formation 11,12. A significant improvement to those systems was brought up by the advent of CRP.…”

Section: Introductionmentioning

confidence: 99%

Synthesis of Silicone‐Methacrylate Copolymers by ATRP Using a Nickel‐Based Supported Catalyst

Duquesne

Habimana²,

Degée

et al. 2006

Macro Chemistry & Physics

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Summary: A nickel (II) bromide catalyst immobilized onto crosslinked diphenylphosphinopolystyrene (PS‐PPh3/NiBr2) was used for the synthesis of silicone‐methacrylate copolymers by atom transfer radical polymerization (ATRP) of various methacrylate monomers using ω‐bromide silicone chains as macroinitiator. The polymerization proved to be very well‐controlled when a sufficient amount of soluble ligand, i.e., triphenylphosphine (PPh3), was added to the polymerization medium. Under these conditions, this technique efficiently led to the production of different copolymers with controlled compositions and molecular weights as well as narrow polydispersity indices ($\overline M _{\rm w} /\overline M _{\rm n}$ < 1.5). The recovered copolymers proved to be almost free of catalyst residues. Indeed, inductively coupled plasma (ICP) analysis revealed a metal content lower than 100 ppm, representing only a few percent of the initial metal content in the polymerization medium.Synthesis of PDMS block copolymer in toluene catalyzed by PS‐PPh3/NiBr2 in the presence of soluble PPh3 at 90 °C.imageSynthesis of PDMS block copolymer in toluene catalyzed by PS‐PPh3/NiBr2 in the presence of soluble PPh3 at 90 °C.

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Block copolymers via thermal polymeric iniferters. Synthesis of silicone-vinyl block copolymers

Cited by 39 publications

References 5 publications

Compatibilization of low-density polyethylene/polystyrene blends by segmented EB(PS-block-EB) n block copolymers

Compatibilization of low-density polyethylene/polystyrene blends by segmented EB(PS-block-EB) n block copolymers

Atom transfer radical polymerization of styrene and methyl (meth)acrylates initiated with poly(dimethylsiloxane) macroinitiator: Synthesis and characterization of triblock copolymers

Synthesis of Silicone‐Methacrylate Copolymers by ATRP Using a Nickel‐Based Supported Catalyst

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