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首页> 外文期刊>Macromolecular chemistry and physics >Micro- and macrophase separation in phenolic resol resin/PEO-PPO-PEO block copolymer blends: Effect of hydrogen-bonded PEO length
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Micro- and macrophase separation in phenolic resol resin/PEO-PPO-PEO block copolymer blends: Effect of hydrogen-bonded PEO length

机译：酚醛酚醛树脂/ PEO-PPO-PEO嵌段共聚物共混物中的微相和宏观相分离：氢键PEO长度的影响

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Full Paper: We demonstrate microphase-separated thermosets based on blends of phenolic resol resin and poly(ethylene oxide)-block-poly(propylene oxide)-block-poly(ethylene oxide) (PEO-PPO-PEO), i.e., so-called Pluronics. Three triblock copolymers are used (PE 9200, PE 10300 and PE 9400) where the molecular weights of the PPO blocks are nearly equal and the weight fractions of the PEO blocks f(PEO) are 0.20, 0.30 and, 0.40, respectively. The blends are prepared in a particularly straightforward way using aqueous solutions and thermal cross-linking. Structure formation is characterized using transmission electron microscopy and small-angle X-ray scattering. PPO turns out to be sufficiently repulsive to allow microphase separation in the bulk crosslinked phase and the tendency for macrophase separation upon curing is reduced due to the hydrogen bonding between the PEO and resol. The weight fraction of PEO-PPO-PEO in the present blends has been limited to a relatively small value, i.e., 20 wt.-%o, and spherical microphase-separated structure U observed for f(PEO) = 0.40 with a long period of the order 120 Angstrom. Macrophase separation manifests upon curing if the weight fraction of the PEO blocks is smaller, 1.e., f(PEO) = 0.30 or f(PEO) = 0.20. In addition, in order to prevent macrophase separation, the molecular weights of PEO blocks and resol resin before curing are of the same order. In that respect, the system behaves qualitatively similar to the corresponding thermoplastic homopolymer/block copolymer blends. [References: 22]
机译：全文：我们展示了基于酚醛酚醛树脂和聚环氧乙烷-嵌段-聚环氧丙烷-嵌段-聚环氧乙烷（PEO-PPO-PEO）的共混物的微相分离热固性树脂，即称为Pluronics。使用三种三嵌段共聚物（PE 9200，PE 10300和PE 9400），其中PPO嵌段的分子量几乎相等，PEO嵌段的重量分数f（PEO）分别为0.20、0.30和0.40。使用水溶液和热交联以特别直接的方式制备共混物。使用透射电子显微镜和小角度X射线散射表征结构形成。事实证明，PPO具有足够的排斥力，可以在本体交联相中进行微相分离，并且由于PEO和甲阶酚醛之间的氢键作用，固化后宏观相分离的趋势得以降低。在本发明共混物中，PEO-PPO-PEO的重量分数被限制在一个相对较小的值，即20wt。％o，并且长时间观察到的f（PEO）= 0.40的球形微相分离结构U约为120埃。如果PEO嵌段的重量分数较小，即e（f（PEO）＝ 0.30或f（PEO）＝ 0.20），则在固化时出现大相分离。另外，为了防止宏观相分离，固化前的PEO嵌段和可熔酚醛树脂的分子量为相同数量级。在这方面，该体系在质量上类似于相应的热塑性均聚物/嵌段共聚物的共混物。 [参考：22]

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