BLOCK COPOLYMERS NEAR THE MICROPHASE SEPARATION TRANSITION .2. LINEAR DYNAMIC MECHANICAL-PROPERTIES
BLOCK COPOLYMERS NEAR THE MICROPHASE SEPARATION TRANSITION .2. LINEAR DYNAMIC MECHANICAL-PROPERTIES
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DOI：
10.1021/ma00142a025
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发表时间：
1984-01-01
期刊：
影响因子：
5.5
通讯作者：
BATES, FS
中科院分区：
文献类型：
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作者：
BATES, FS
对三种1，4-聚丁二烯-1，2-聚丁二烯二嵌段共聚物在微相分离转变（MST）附近的流变行为进行了研究。低频线性动态剪切模量被证明是强烈依赖于这些样品的相态，表现出上临界温度。通过MST加热含有38%1，4-聚丁二烯的微相分离（有序）样品在温度Tm下产生弹性模量和动态粘度的不连续性，对应于从有序到无序（均匀）状态的一级熔体转变。从无序状态冷却不会在Tm下产生模量的不连续性;相反，聚合物熔体在温度稳定极限Ts< Tm下表现出亚稳态行为。低于Tt时，粘弹性响应是微相分离嵌段共聚物的特征，与热历史无关。这些研究结果定量验证了预测的相行为，其特征在于由一个临界温度上限的二嵌段共聚物。
Three 1, 4-polybutadiene-l, 2-polybutadiene diblockcopolymers near the microphase separation transition (MST) have been examined theologically. The low-frequency linear dynamic shear moduli are shown to be strongly dependent on the phase state of these samples, which exhibit an upper critical temperature. Heating a microphase-separated (ordered) sample containing 38% 1, 4-polybutadiene through the MST produces a discontinuity in both theelastic modulus and dynamic viscosity at a temperature Tm, corresponding to the first-order melt transition from the ordered to the disordered (homogeneous) state. Coolingfrom the disordered state produces no discontinuity in the moduli at Tm; instead, the polymer melt exhibits metastable behavior down to the stability limit in temperature, Ts< Tm. Below Tt, the viscoelastic responseis characteristic of microphase-separated block copolymer, regardless of thermal history. These findings quantitatively verify the predicted phase behavior for diblock copolymers characterized by an upper critical temperature.