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Supersoft and Hyperelastic Polymer Networks with Brushlike Strands
Macromolecules ( IF 5.5 ) Pub Date : 2018-01-11 00:00:00 , DOI: 10.1021/acs.macromol.7b02555
Heyi Liang 1 , Sergei S. Sheiko 2 , Andrey V. Dobrynin 1
Affiliation  

Using a combination of the scaling analysis and molecular dynamics simulations, we study relationship between mechanical properties of networks of graft polymers and their molecular architecture. The elastic response of such networks can be described by replacing the brushlike strands with wormlike strands characterized by the effective Kuhn length which is controlled by the degree of polymerization of the side chains nsc and their grafting density 1/ng. In the framework of this approach we have established relationships between the network structural shear modulus G, strands extension ratio β, and architectural triplet [nsc, ng, nx], where nx is the degree of polymerization of the backbone strand between cross-links. Analysis of the simulation data shows that G could increase with β (G ∝ β), which reflects the “golden rule” of elastomers: softer materials are more deformable. However, networks of graft polymers can also break this rule and demonstrate an increase of the modulus G with decreasing extension ratio β such as G ∝ β–2. This can be achieved by changing the grafting density of the side chains 1/ng and keeping nx and nsc constant. This peculiar mechanical response of graft polymer networks is in agreement with experimental studies of poly(dimethylsiloxane) graft polymer elastomers.

中文翻译:

带有刷状链的超软和超弹性聚合物网络

通过结合使用比例分析和分子动力学模拟,我们研究了接枝聚合物网络的机械性能与其分子结构之间的关系。这种网络的弹性响应可通过用特征为有效库恩长度的蠕虫状链代替刷状链来描述,该有效库恩长度由侧链的聚合度n sc和它们的接枝密度1 / n g控制。在这种方法的框架中,我们已经建立了网络结构剪切模量G,线股延伸率β和建筑三元组之间的关系[ n scn gnx ],其中n x是交联之间主链的聚合度。对模拟数据的分析表明,G可以随β(G ∝β)增加,这反映了弹性体的“黄金法则”:较软的材料更易变形。但是,接枝聚合物网络也可以打破这一规律,并证明随着延伸率β的降低,模量G会增加,例如G ∝β –2。这可以通过更改侧链1 / n g的接枝密度并保持n xn sc来实现持续的。接枝聚合物网络的这种独特的机械响应与聚(二甲基硅氧烷)接枝聚合物弹性体的实验研究一致。
更新日期:2018-01-11
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