在不混合的玻璃-领域之间形成聚合物-聚合物接口时,开发广泛的模量概况
Yannic J Gagnon1, Justin C Burton1, Connie B Roth1
1Department of Physics, Emory University, Atlanta, GA 30322.
概括
聚合物薄膜中的接口在材料特性中产生长距离的梯度. 这项研究揭示了这些局部模量和玻璃过渡温度的梯度是如何从接口形成期间的声阻抗匹配中产生的.
科学领域:
- 材料科学 材料科学 材料科学
- 聚合物物理 聚合物物理
- 软物质物理学 软物质物理学
背景情况:
- 玻璃材料中的接口表现出异质的动态.
- 之前的研究表明,在聚合物双层中,玻璃过渡温度 (Tg) 的长距离梯度 (∼200 nm) 很大.
- 了解这些梯度是阐明眼镜动态异质性的关键.
研究的目的:
- 在聚合物双层系统中证明局部模量 (G) 的长距离梯度.
- 调查接口形成和属性梯度之间的关系.
- 探索这些广泛的财产形状背后的机制.
主要方法:
- 制造两层聚乙烯 (PS) 和聚乙烯 (PB) 薄膜.
- 使用石英晶体微平衡 (QCM) 与连续物理模型来测量粘弹性特性.
- 在接口演化过程中分析了PB/PS双层的剪切波传播.
主要成果:
- 在局部模量 (G) 中建立了大约180nm的长距离梯度.
- 观察到局部Tg的宽度梯度与之前的发现一致.
- 测量聚合物-聚合物接口宽度大约为5nm.
结论:
- 局部模量和玻璃过渡温度的宽度梯度是由聚合物-聚合物接口上的振动模式的合引起的.
- 在接口扩展过程中,声波 (∼20 nm) 的声阻匹配是关键机制.
- 这种合可以触发邻近领域的密度波动,影响材料特性.
相关概念视频
Polymer Classification: Crystallinity
2.9K
Unlike ionic or small covalent molecules, polymers do not form crystalline solids due to the diffusion limitations of their long-chain structures. However, polymers contain microscopic crystalline domains separated by amorphous domains.
Crystalline domains are the regions where polymer chains are aligned in an orderly manner and held together in proximity by intermolecular forces. For example, chains in the crystalline domains of polyethylene and nylon are bound together by van der Waals...
Crystalline domains are the regions where polymer chains are aligned in an orderly manner and held together in proximity by intermolecular forces. For example, chains in the crystalline domains of polyethylene and nylon are bound together by van der Waals...
2.9K
Molecular Weight of Step-Growth Polymers
2.2K
Step growth polymerization involves bi or multifunctional monomers. Bifunctional monomers react to form linear step growth polymers, whereas multifunctional monomers react to form non-linear or branched polymers.
As the step-growth polymerization involves step-wise condensation of monomers, the molecular weight also builds up eventually. Consequently, high molecular weight polymers are obtained at the late stages of the polymerization, where 99% of monomers have been consumed.
The extent of the...
As the step-growth polymerization involves step-wise condensation of monomers, the molecular weight also builds up eventually. Consequently, high molecular weight polymers are obtained at the late stages of the polymerization, where 99% of monomers have been consumed.
The extent of the...
2.2K
Polymer Classification: Architecture
2.7K
Polymers are classified as linear or branched on the basis of their chain architecture. The polymer chains in linear polymers have a long chain-like structure with minimal to no branching at all. Even if a polymer features large substituent groups on the monomer, which appear as branches to the skeleton, it is not considered a branched polymer. A branched polymer contains secondary polymer chains that arise from the main polymer chain. The branching occurs when the polymer growth shifts from...
2.7K
Step-Growth Polymerization: Overview
3.5K
Step-growth or condensation polymerization is a stepwise reaction of bi or multifunctional monomers to form long-chain polymers. As all the monomers are reactive, most of the monomers are consumed at the early stages of the reaction to form small chains of reactive oligomers, which then combine to form long polymer chains in the late stages. Hence, the reaction has to proceed for a long time to achieve high molecular weight polymers.
Many natural and synthetic polymers are produced by...
Many natural and synthetic polymers are produced by...
3.5K
Polymer Classification: Stereospecificity
2.4K
Polymerization generates chiral centers along the entire backbone of a polymer chain. Accordingly, the stereochemistry of the substituent group has a significant effect on polymer properties. Polymers formed from monosubstituted alkene monomers feature chiral carbons at every alternate position in the polymer backbone. Relative to the predominant orientation of substituents at the adjacent chiral carbons, the polymer can exist in three different configurations: isotactic, syndiotactic, and...
2.4K


