Impact of Molecular Architecture on Dynamics of Miktoarm Star Copolymers,Macromolecules

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Impact of Molecular Architecture on Dynamics of Miktoarm Star Copolymers
Macromolecules ( IF 5.1 ) Pub Date : 2018-07-13 00:00:00 , DOI: 10.1021/acs.macromol.8b00624
Thomas Kinsey , Emmanuel Urandu Mapesa , Weiyu Wang ₁ , Kunlun Hong ₁ , Jimmy Mays ₁ , S. Michael Kilbey , Joshua Sangoro

Affiliation

Broadband dielectric spectroscopy (BDS) is used to probe the chain and segmental dynamics of A₂B₂ and AB₂ miktoarm star copolymers based on polystyrene (PS, A block) and polyisoprene (PI, B block) that display lamellar morphologies as determined using small-angle X-ray scattering (SAXS). While no changes in the distribution of PI segmental relaxation times are observed with variation of the molecular architecture, an unexpected increase in the normalized PI chain relaxation intensity is realized for AB₂ miktoarm star copolymers as well as a change in the distribution of chain relaxation rates as compared to A₂B₂ and AB diblock copolymer systems. This result is attributed to asymmetry in the molecular architecture near the junction point, which affects the osmotic constraint of the tethered PI chains within the interfacial region of the lamellae. The results highlight the importance of macromolecular design on fundamental chain dynamics in phase-separated thermoplastic elastomers.

中文翻译：

分子结构对Miktoarm星型共聚物动力学的影响

宽带介电谱（BDS）用于探查基于聚苯乙烯（PS，A嵌段）和聚异戊二烯（PI，B嵌段）的A ₂ B ₂和AB ₂轻链星形共聚物的链和链段动力学，该共聚物显示出层状形态，通过使用小角X射线散射（SAXS）。尽管没有观察到分子结构变化引起的PI链段弛豫时间分布的变化，但对于AB ₂ miktoarm star共聚物而言，归一化的PI链弛豫强度却出乎意料地增加，而且链弛豫率的分布也发生了变化。与A ₂ B ₂相比和AB二嵌段共聚物体系。该结果归因于在接合点附近的分子结构中的不对称，这影响了薄片界面区域内的束缚PI链的渗透约束。结果突出了大分子设计对于相分离热塑性弹性体中基本链动力学的重要性。

更新日期：2018-07-13

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