A Separation Method of Responses from Large Scale Motions and Chain Relaxations for Viscoelastic Properties of Symmetric Poly(styrene-<i>b</i>-2-vinylpyridine)s in the Ordered State

Abstract

Separation method of responses from large scale motions and polymer chain motions are investigated for viscoelastic properties of symmetric poly(styrene-b-2-vinylpyridine)s (SP) in the ordered state taking into account of the effects of flow history on the sample. Due to the almost same thermo-rheological properties of components, master curves of dynamic moduli for SP, G* SP are obtained and shown that the data well coincide with those of polystyrene homopolymers (hPS) at high frequency ω, while responses from large scale motions of lamellar structure, ∆G* grain are observed at low ω, which asymptote to ∆G* grain ~ ω 0.5 . After the pre-shear, magnitude of ∆G* grain became lower at the lower ω region. When the magnitude of G* SP are appropriately higher than ∆G* grain extended to higher ω, ∆G* grain and the responses of polymer chains, ∆G* chain , having Rouse like modes, are successfully obtained by subtraction, ∆G* chain = G* SP -∆G* grain , irrespective of pre-shear. By combining thus obtained ∆G* grain, ∆G* chain , and the data for hPS, G* hPS at higher ω region, G* SP data can be well approximated in a whole frequency range of the measurement.

Structural Dynamics of Strongly Segregated Block Copolymer Electrolytes

“…In constrast to the PS data, the SEO and SEO-LiTFSI samples do not display a τ rep or terminal flow, but rather both G ′ and G ″ scale as ω 1/2 . This is attributed to the phase-separated structure and agrees with other reports of unaligned lamellar block copolymers. , The soft glassy rheology model predicts that at low frequency G ′ and G ″ both scale as ω x –1 when 1 < x < 2. Interactions between different structurally rearranging regions are subsumed into this dimensionless noise temperature, x . − With increasing r , the low-frequency slope of log­( G ′) versus log­(ω) of SEO-LiTFSI samples exponentially decays from the salt-free value of 0.47 to an asymptotic value of 0.28 at high salt concentration.…”

“…Another study of BCP rheology used poly­(styrene- b -2-vinylpyridine), PS- b -P2VP, with components that have similar thermorheological behavior. The grain contribution (extrapolated from low frequency) and PS contribution were subtracted from the BCP master curve to yield the P2PV chain contribution . Because of the significantly differents T g ’s of our components, we have not attempted this.…”

“…This is attributed to the phase-separated structure and agrees with other reports of unaligned lamellar block copolymers. 78,79 The soft glassy rheology model predicts that at low frequency G′ and G″ both scale as ω x−1 when 1 < x < 2. Interactions between different structurally rearranging regions are subsumed into this dimensionless noise temperature, x.…”

“…The grain contribution (extrapolated from low frequency) and PS contribution were subtracted from the BCP master curve to yield the P2PV chain contribution. 79 Because of the significantly differents T g 's of our components, we have not attempted this. The entanglement relaxation time for PEO at 75 °C has been reported as 1.5 × 10 −8 s (M N = 932 kg/mol), 76 and that of PS at 110 °C has been reported as 102 s (M N = 96 kg/mol).…”

Molecular Weight Dependence of Viscoelastic Properties for Symmetric Poly(styrene-b-2-vinylpyridine)s in the Nanophase Separated Molten States

“…In the ordered state, textured fluid behavior is observed for SP-21K, SP-29K, and SP-46.9K (see Table ) under steady shear flow similarly as in solutions, , implying that the multigrain structures of these samples are controlled by the shear rate when steady states are achieved. However, the well-aligned state was only achieved for SP-21K in those samples …”