Controlled Anionic Polymerization of Hexamethylcyclotrisiloxane. Model Linear and Miktoarm Star Co- and Terpolymers of Dimethylsiloxane with Styrene and Isoprene

Bellas, Vasilios; Iatrou, Hermis; Hadjichristidis, N.

doi:10.1021/ma000635i

Cited by 173 publications

(206 citation statements)

References 22 publications

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“…The living anionic polymerization of D 3 has recently been much advanced by Hadjichristidis and his coworkers, with special care to well control the polymerization. Highly reactive living anionic polymers of styrene and isoprene initiate the polymerization of D 3 to afford well-defined AB diblock copolymers of PS-b-PDMS and PI-b-PDMS [48]. It was also reported that an BAB triblock copolymer of PDMS-b-poly(4-vinylpyridine) (P4VP)-b-PDMS could be synthesized by sequential polymerization Similarly, it was observed that the linking reaction of living P2VP quantitatively occurred with ω-chain-end-BnCl-functionalized PDMS in the presence of a catalytic amount of CsI even at −78 °C to afford a well-defined PDMS-b-P2VP (M n = 20.2 kg/mol, M w /M n = 1.07, PDMS (w/w, %) = 20%) (see also Scheme 3).…”

Section: Synthesis Of Block Polymers By a Linking Methodology Using Amentioning

confidence: 99%

Precise Synthesis of Block Polymers Composed of Three or More Blocks by Specially Designed Linking Methodologies in Conjunction with Living Anionic Polymerization System

et al. 2013

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This article reviews the successful development of two specially designed linking methodologies in conjunction with a living anionic polymerization system for the synthesis of novel multiblock polymers, composed of three or more blocks, difficult to be synthesized by sequential polymerization. The first methodology with the use of a new heterofunctional linking agent, 2-(4-chloromethylphenyl)ethyldimethylchlorosilane (1), was developed for the synthesis of multiblock polymers containing poly(dimethylsiloxane) (PDMS) blocks. This methodology is based on the selective reaction of the chain-end silanolate anion of living PDMS, with the silyl chloride function of 1, and subsequent linking reaction of the resulting ω-chain-end-benzyl chloride-functionalized polymer with either a living anionic polymer or living anionic block copolymer. With this methodology, various multiblock polymers containing PDMS blocks, up to the pentablock quintopolymer, were successfully synthesized. The second methodology using an α-phenylacrylate (PA) reaction site was developed for the synthesis of multiblock polymers composed of all-vinyl polymer blocks. In this methodology, an α-chain-end-PA-functionalized polymer or block copolymer, via the living anionic polymerization, was first prepared and, then, reacted with appropriate living anionic polymer or block copolymer to link the two polymer chains. As OPEN ACCESSPolymers 2013, 5 1013 a result, ACB (BCA), BAC (CAB), (AB) n , (AC) n , ABA, ACA, BCB, and ABCA multiblock polymers, where A, B, and C were polystyrene, poly(2-vinylpyridine), and poly(methyl methacrylate) segments, could be successfully synthesized. The synthesis of triblock copolymers, BAB, CAC, and CBC, having molecular asymmetry in both side blocks, was also achieved. Furthermore, the use of living anionic polymers, derived from many other monomers, categorized as either of styrene, 2-vinylpyridine, or methyl methacrylate in monomer reactivity, in the linking methodology enabled the number of synthetically possible block polymers to be greatly increased. Once again, all of the block polymers synthesized by these methodologies are new and cannot be synthesized at all by sequential polymerization. They were well-defined in block architecture and precisely controlled in block segment.

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Section: Synthesis Of Block Polymers By a Linking Methodology Using Amentioning

confidence: 99%

Precise Synthesis of Block Polymers Composed of Three or More Blocks by Specially Designed Linking Methodologies in Conjunction with Living Anionic Polymerization System

et al. 2013

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“…8,9 This leads to good molecular weight control, but back-biting can become problematic at high monomer conversions. [10][11][12][13] Controlled-structure PDMS-based materials have various applications in polymer and colloid science. 2, 14 For example, monomethacrylate-capped PDMS macromonomers have been utilized as reactive steric stabilizers for the preparation of PDMS-stabilized latexes in supercritical CO 2 15,16 .…”

Section: Introductionmentioning

confidence: 99%

Polydimethylsiloxane-Based Diblock Copolymer Nano-objects Prepared in Nonpolar Media via RAFT-Mediated Polymerization-Induced Self-Assembly

et al. 2015

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and relatively low final polydispersities (M w /M n = 1.14 -1.34). Small-angle X-ray scattering (SAXS) has been used to characterize selected examples of the spherical nanoparticles in order to obtain volume-average diameters, which increase monotonically when targeting longer DPs for the coreforming PBzMA block. A relatively high copolymer concentration (> 25 % w/v) is required to obtain a pure worm phase, which occupies an extremely narrow region within the phase diagram. Selected worm and vesicle dispersions were also analyzed by SAXS, which enables determination of the mean worm cross-section, mean worm length and vesicle membrane thickness, respectively. In addition, the highly anisotropic worms formed free-standing gels in n-heptane, with rheology measurements indicating viscoelastic behavior and a gel storage modulus of around 10 4 Pa.

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“…However, the formed layer is internally highly mobile and not at all glassy. The size of this layer, which is directly accessed by the time-and length-scale-dependent neutron scattering experiments, significantly exceeds the length scale of the directly adsorbed polymer, presenting the first direct microscopic evidence for the hypothetical interphase.PDMS with a molecular weight of 17:4 kg=mol (M w =M n ¼ 1:21, protonated h-PDMS) and 21:2 kg=mol (M w =M n ¼ 1:16, deuterated d-PDMS) was synthesized by living anionic polymerization [15]. With an entanglement molecular weight M e ¼ 12 kg=mol, these molecular weights in the bulk practically represent an unentangled system.…”

mentioning

confidence: 99%

“…PDMS with a molecular weight of 17:4 kg=mol (M w =M n ¼ 1:21, protonated h-PDMS) and 21:2 kg=mol (M w =M n ¼ 1:16, deuterated d-PDMS) was synthesized by living anionic polymerization [15]. With an entanglement molecular weight M e ¼ 12 kg=mol, these molecular weights in the bulk practically represent an unentangled system.…”

mentioning

confidence: 99%

Effect of Nanoconfinement on Polymer Dynamics: Surface Layers and Interphases

et al. 2013

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We present neutron spin echo experiments that address the much debated topic of dynamic phenomena in polymer melts that are induced by interacting with a confining surface. We find an anchored surface layer that internally is highly mobile and not glassy as heavily promoted in the literature. The polymer dynamics in confinement is, rather, determined by two phases, one fully equal to the bulk polymer and another that is partly anchored at the surface. By strong topological interaction, this phase confines further chains with no direct contact to the surface. These form the often invoked interphase, where the full chain relaxation is impeded through the interaction with the anchored chains. The investigation of liquids under nanoconfinement has been a topic of intense scientific scrutiny for decades [1]. The issues are glass transition, crystallization, and phase separation under confinement [2,3]. Recently, this interest has been amplified by the rising of nanotechnology that aims to create new properties by modifying materials at the nanoscale. Polymers are of particular interest since they offer a large range of applications such as coatings, lubrication, nanocomposites, and in the field of biological macromolecules, biosensors [4].Close to a confining surface, the conformations of a polymer are significantly restricted [5]. In addition, the interactions with the surface will strongly affect the dynamics. Related issues such as adsorption, friction, network formation, effects on the entanglement density, and polymer density changes under confinement have been studied [6][7][8][9]. The importance of these phenomena thereby depends on the type of polymer, the specificity of the interactions, and the topology of the confinement. In particular, experimental results have been interpreted in terms of the formation of a glassy polymer layer close to surfaces [7]. Furthermore, the existence of an interphase with properties between those of the glassy layer and the bulk has been hypothesized [10][11][12].A large number of experimental studies have focused on nanoparticles dispersed in a polymer matrix. Whereas for noninteracting polymers significant effects only occur at high particle loadings, the addition of nanoparticles that interact with a polymer matrix induces dramatic property changes for the resulting polymer nanocomposite [7,9,10,13,14]. In particular, it has been reported that the interaction between OH groups on the surface of nanoparticles and locally polar poly(ethylene oxide) (PEO) or polydimethylsiloxane (PDMS) chains lead to the formation of a glassy polymer layer [7,10,13]. Theoretical work and computer simulations of chain adsorption as a function of adsorption strength reveal the existence of different chain conformations including trains, loops, and tails [14].Here, we present an investigation on the dynamics of PDMS chains confined in anodic aluminum oxide (AAO) nanopores. We find that PDMS adsorbs at the surface. However, the formed layer is internally highly mobile and not at all glassy. The siz...

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Controlled Anionic Polymerization of Hexamethylcyclotrisiloxane. Model Linear and Miktoarm Star Co- and Terpolymers of Dimethylsiloxane with Styrene and Isoprene

Cited by 173 publications

References 22 publications

Precise Synthesis of Block Polymers Composed of Three or More Blocks by Specially Designed Linking Methodologies in Conjunction with Living Anionic Polymerization System

Precise Synthesis of Block Polymers Composed of Three or More Blocks by Specially Designed Linking Methodologies in Conjunction with Living Anionic Polymerization System

Polydimethylsiloxane-Based Diblock Copolymer Nano-objects Prepared in Nonpolar Media via RAFT-Mediated Polymerization-Induced Self-Assembly

Effect of Nanoconfinement on Polymer Dynamics: Surface Layers and Interphases

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