Chain Dynamics and Structure of Polymer Interfaces

聚合物界面的链动力学和结构

• 批准号: 9403911
• 负责人: Richard Wool
• 金额: $ 8万
• 依托单位: University of Illinois at Urbana-Champaign
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1994
• 资助国家: 美国
• 起止时间: 1994-07-01 至 1995-10-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9403911&HistoricalAwards=false
• 关键词: Chain; Dynamics; Structure; Polymer; Interfaces

Wool The question of whether polymer molecules reptate or not remains as one of the most important and controversial problems in polymer physics. The reptation model was proposed by P.-G. de Gennes (1971) to describe the dynamics of linear polymer chains in the melt. We have designed an experiment which probes the essential features of this model, i.e., the snakelike motion of chains due to their confinement by the other chains, and related scaling laws. We explore the interdiffusion of two sets of matching triblock chains, HDH/DHD, where the chain centers are deuterated on one side (HDH) and the chain ends (DHD) are deuterated on the other side of the interface. If the chains reptate, a characteristic "ripple" develops in the concentration profile CD(x, t) which grows to a maximum and then decays. The ripple is due to the anisotropic motion of the chains. Our initial Ripple experiments Nature, 365, 235, Sept 1993 using SIMS and Neutron Reflection analysis of matching polystyrene triblocks provide strong support for reptation. Several critical experiments remain to complete the investigation of the reptation model using matching triblocks. These include (a) the effects of molecular weight at M Mc, (b) the effects of Rouse dynamics at M Mc (critical entanglement molecular weight), (c) location of chain ends, (d) effects of chemistry, (e) scaling behavior with time and molecular weight, (f) quantitative comparision between computer simulation and experiment, and others. These experiments should provide a definitive statement on the validity of the reptation model. %%% Reptation is a key concept in the motions of linear polymer chains. A validation, or negation, of this model would have important consequences in such areas as the healing of cracks in rubber or plastics.

羊毛 聚合物分子是否重复的问题仍然是聚合物物理学中最重要和最有争议的问题之一。 爬行模型是由 P.-G. 提出的。 de Gennes (1971) 描述了熔体中线性聚合物链的动力学。 我们设计了一个实验，探讨该模型的基本特征，即由于受到其他链的限制而导致的链的蛇形运动，以及相关的缩放定律。 我们探索了两组匹配的三嵌段链 HDH/DHD 的相互扩散，其中链中心在界面的一侧（HDH）被氘化，链末端（DHD）在界面的另一侧被氘化。 如果链重复，则浓度分布 CD(x, t) 中会出现特征“波动”，该“波动”增长至最大值，然后衰减。 波纹是由于链条的各向异性运动造成的。 我们最初的波纹实验 Nature, 365, 235, Sept 1993 使用 SIMS 和匹配聚苯乙烯三嵌段的中子反射分析为蠕动提供了强有力的支持。 仍有几个关键实验需要完成使用匹配三嵌段的爬行模型的研究。 这些包括（a）M Mc 分子量的影响，（b）M Mc （临界缠结分子量）劳斯动力学的影响，（c）链端位置，（d）化学影响，（e）随时间和分子量的缩放行为，（f）计算机模拟与实验之间的定量比较等。 这些实验应该为爬行模型的有效性提供明确的陈述。 %%% 蠕动是线性聚合物链运动的一个关键概念。 该模型的验证或否定将对橡胶或塑料裂纹的愈合等领域产生重要影响。