Linear viscoelastic behavior of densely grafted poly(chloroethyl vinyl ether)-<i>g</i>-polystyrene combs in the melt

Bailly, Christian; Stephenne, Vincent; Muchtar, Zainuddin; Schappacher, Michel; Deffieux, Alain

doi:10.1122/1.1579688

Cited by 27 publications

(19 citation statements)

References 27 publications

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“…At low reduced frequencies, all of the polymers exhibit terminal flow evidenced by G ′ ∼ ω 2 , G ″ ∼ ω, and G ′ < G ″. At high reduced frequencies, Rouse scaling of G ′ ∼ G ″ ∼ ω 1/2 is observed, which is characteristic of unentangled polymer melts and has been previously reported for bottlebrush polymers. ,− For the higher M w samples in Figure ( n bb ≥ 640), a third regime is apparent at intermediate reduced frequencies, characterized by a plateau in G ′ associated with molecular entanglements as predicted by the reptation model. ,, Note that the side chains do not entangle because the graft chain molar mass is lower than the entanglement molar mass ( M e ) for polylactide . These observations are in good agreement with previous reports on sparsely grafted polymers. , …”

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confidence: 69%

Consequences of Grafting Density on the Linear Viscoelastic Behavior of Graft Polymers

et al. 2018

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The linear viscoelastic behavior of poly(norbornene)-graft-poly(±-lactide) was investigated as a function of grafting density and overall molar mass. Eight sets of polymers with grafting densities ranging from 0 to 100% were synthesized by living ring-opening metathesis copolymerization. Within each set, the graft chain molar mass and spacing between grafts were fixed, while the total backbone length was varied. Dynamic master curves reveal that these polymers display Rouse and reptation dynamics with a sharp transition in the zero-shear viscosity data, demonstrating that grafting density strongly impacts the entanglement molar mass. The entanglement modulus (G e) scales with inverse grafting density (n g) as G e ∼ n g 1.2 and G e ∼ n g 0 in accordance with scaling theory in the high and low grafting density limits, respectively. However, a sharp transition between these limiting behaviors occurs, which does not conform to existing theoretical models for graft polymers. A molecular interpretation based on thin flexible chains at low grafting density and thick semiflexible chains at high grafting density anticipates the sharp transition between the limiting dynamical regimes.

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confidence: 69%

Consequences of Grafting Density on the Linear Viscoelastic Behavior of Graft Polymers

et al. 2018

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“…Loosely to densely grafted PS combs, 3 ≤ N br < 30 (see Figure ), showed a clear crossover of G′ and G″ (Figure a) in the low-frequency region, which was attributed to the reptation of innermost backbone segments as they have the longest relaxation times. The absence of this crossover and the power-law dependency of G′ and G″ ∼ ω 0.6 for densely grafted comb and bottlebrush PS with N br ≥ 60 ( Z s < 0.3) demonstrated the presence of the Rouse relaxation mechanism of the inner backbone segments along with dynamic dilution of the side chains rather than the reptation mechanism …”

Section: Resultsmentioning

confidence: 97%

“…The absence of this crossover and the powerlaw dependency of G′ and G″ ∼ ω 0.6 for densely grafted comb and bottlebrush PS with N br ≥ 60 (Z s < 0.3) demonstrated the presence of the Rouse relaxation mechanism of the inner backbone segments along with dynamic dilution of the side chains rather than the reptation mechanism. 40 Figure 5b shows the absolute value of the complex viscosity along with Maxwell model fittings (relaxation spectra, g i and λ i , are in Table S1), which were used to calculate the zero-shear viscosities by extrapolating data to the enough low angular frequency region η 0 = ∑g i λ i . The plateau in the complex viscosity in the intermediate frequency regime, ∼1 rad/s, is related to the side chain relaxation time.…”

Section: ■ Msf Constitutive Equationmentioning

confidence: 99%

Linear and Extensional Rheology of Model Branched Polystyrenes: From Loosely Grafted Combs to Bottlebrushes

2017

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Monodisperse comb polystyrenes (comb-PS) with loosely to densely grafted architectures up to loosely grafted bottlebrush structures were synthesized via anionic polymerization. This comb-PS series, named PS290-N br -44, had the same entangled backbone, M w,bb = 290 kg/mol, corresponding to a number of entanglements along the backbone Z bb ≅ 20, and similar branch length, M w,br ≅ 44 kg/ mol or Z br ≅ 3, but varied in the number of branches per molecule, N br , from 3 to 190 branches. Consequently, the average number of entanglements between two consecutive branch points along the backbone (branch point spacing), Z s , ranged from well entangled, Z s ≅ 5, to values that were far less than one entanglement, Z s ≅ 0.1. Linear viscoelastic data including the zero-shear rate viscosity, η 0 , diluted modulus, G N,s 0 , and a new diluted modulus extracted from the van Gurp−Palmen plot, |G*| at δ = 60°, were analyzed as a function of the M w of the combs. Scaling of η 0 versus M w revealed three different regions for increasing N br or decreasing Z s : (1) loosely grafted combs with Z br < Z s and η 0 ∼ exp(M w ), ( 2) densely grafted combs with 1 < Z s < Z br and η 0 ∼ M w −3.4 followed by η 0 ∼ M w −1 for 0.2 < Z s < 1, and (3) loosely grafted bottlebrushes with Z s < 0.2 and η 0 ∼ M w 5 . The relative maximum in η 0 corresponded to a comb-PS with Z s ≅ Z br , and the relative minimum resulted from a comb-PS with Z s ≅ 0.2, which displayed almost the same η 0 as the linear PS290. Strain hardening factors, SHF ≡ η E,max /η DE,max , measured in extensional experiments increased with increasing N br and reached SHF > 200 for Hencky strains below ε H = 4, which is tremendously high and has to the best of our knowledge not been observed yet. Such a high strain hardening is of great fundamental and technical importance in extensional processes, e.g., foaming, film blowing, or fiber spinning.

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“…3−5 Such a high degree of supramolecular order was attributed to enhanced mobility in bottlebrush copolymer melts due to a low density of entanglements despite their extremely high molecular weights (M n > 1 million Da). 6,7 Bottlebrush block copolymer selfassembly provides access to ordered nanomaterials with large periodicities, which are required for the preparation of a variety of advanced materials, such as ultrafiltration membranes 8,9 and photonic band gap materials. 10 There are three major synthetic strategies for the preparation of bottlebrush block copolymers: "grafting-through," 4,5 "grafting-to", 11,12 and "grafting-from".…”

mentioning

confidence: 99%

“…Bottlebrush copolymers, or molecular brushes, are comb-like macromolecules with short polymeric branches densely grafted along a long polymeric backbone. , Steric crowding of the side chains forces the backbone to acquire a nearly stretched conformation, with bottlebrush macromolecules adopting a cylindrical shape. Recently, diblock bottlebrush block copolymers, comprised of two distinct sets of branches, have been synthesized and shown to self-assemble into remarkably ordered periodic nanomaterials with large domain spacings ( d lam > 70 nm). − Such a high degree of supramolecular order was attributed to enhanced mobility in bottlebrush copolymer melts due to a low density of entanglements despite their extremely high molecular weights ( M n > 1 million Da). , Bottlebrush block copolymer self-assembly provides access to ordered nanomaterials with large periodicities, which are required for the preparation of a variety of advanced materials, such as ultrafiltration membranes , and photonic band gap materials …”

mentioning

confidence: 99%

Tandem RAFT-ATRP Synthesis of Polystyrene–Poly(Methyl Methacrylate) Bottlebrush Block Copolymers and Their Self-Assembly into Cylindrical Nanostructures

Bolton

Rzayev

2011

ACS Macro Lett.

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A polystyrene−poly(methyl methacrylate) (PS-PMMA) bottlebrush block copolymer with asymmetric branches was synthesized by grafting from a symmetrical backbone containing a novel dual vinyl initiation system and characterized by atomic force microscopy (AFM) and small-angle X-ray scattering (SAXS). The block copolymer backbone was prepared by sequential reversible addition−fragmentation chain transfer (RAFT) copolymerization of solketal methacrylate (SM) and 2-(bromoisobutyryl)ethyl methacrylate (BIEM). From the poly-(BIEM) segment, PMMA branches of 26 units were grafted by atom transfer radical polymerization (ATRP). Solketal groups were then subjected to hydrolysis and functionalized with a RAFT agent. Subsequently, from RAFT sites of the poly(SM) segment, polystyrene branches of 45 units were grafted to yield the final bottlebrush block copolymer. The resulting polymer was found to have a vertically oriented cylindrical morphology by AFM with an average cylinder diameter of 45 nm; morphology was also confirmed by SAXS analysis.

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Linear viscoelastic behavior of densely grafted poly(chloroethyl vinyl ether)-g-polystyrene combs in the melt

Cited by 27 publications

References 27 publications

Consequences of Grafting Density on the Linear Viscoelastic Behavior of Graft Polymers

Consequences of Grafting Density on the Linear Viscoelastic Behavior of Graft Polymers

Linear and Extensional Rheology of Model Branched Polystyrenes: From Loosely Grafted Combs to Bottlebrushes

Tandem RAFT-ATRP Synthesis of Polystyrene–Poly(Methyl Methacrylate) Bottlebrush Block Copolymers and Their Self-Assembly into Cylindrical Nanostructures

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