Chain Entropy and Polymerization Thermodynamics: Quantifying Nanoconfinement Effects

链熵和聚合热力学：量化纳米限制效应

• 批准号: 1610614
• 负责人: Sindee Simon
• 金额: $ 39万
• 依托单位: Texas Tech University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-05-01 至 2019-04-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1610614&HistoricalAwards=false
• 关键词: Chain; Entropy; Polymerization; Thermodynamics; Quantifying

NON-TECHNICAL SUMMARY:The chemistry used to create polymeric materials is called polymerization. For many applications it is important to make such polymeric materials within extremely tight spaces, even down to the nanoscale (i.e. to thicknesses about 10,000 times smaller than the thickness of a human hair). This process is called nanoconfinement. In this project, polymerization under nanoconfinement will be studied and theoretical predictions will be tested. The results of the research are important for a fundamental understanding of confined polymerization in nanoelectronic and nanolithography processes, and thus could facilitate technological advances important to these industries. In addition, the results have implications for understanding biopolymers and proteins in biological systems where, for example, protein polymerization can occur in confined environments. The project includes the training of one graduate student, one postdoctoral researcher, and an undergraduate researcher in cutting-edge research involving polymer chemistry and physics at the nanoscale. Ethics training will be incorporated into the training of the students. The PI has a strong track record working with minority and female students, and a vigorous effort will similarly be made to include underrepresented students in this project. Outreach will include organization of two one-week-long polymer modules for the TTU program, "Science -- It's a Girl Thing," for girls in junior high school, and the development of four two-hour modules for the TTU Super Saturdays science program for 4th to 6th graders. TECHNICAL SUMMARY:The fundamental question of entropy loss on confining a chain to a nanopore is addressed, and theories for the scaling of confinement entropy with chain size and nanoconfinement size and dimension will be tested. The entropy loss on confining a chain to a nanopore will be directly determined from the difference in the entropy change on reaction in nanoconfined and bulk conditions. The research focuses on nanoconfined free radical n-alkyl methacrylate polymerizations since the thermodynamics of these systems in the bulk case are well understood. Monomer/polymer equilibria will be studied using calorimetry as a function of reaction temperature and confinement conditions, ranging from weak confinement for dilute solutions in large cylindrical pores to strong confinement for undiluted monomer in small spherical cavities. Monomer and initiator concentrations will be varied to change molecular weight independent of pore size and reaction temperature, whereas pore surface chemistry and monomer structure will be varied to change interfacial interactions. In addition, comparisons will be made with nanoparticle-filled systems having similar surface to volume ratios as the nanoporous matrices but without the chain confining constraints.

非技术摘要：用于创建聚合物材料的化学作用称为聚合。 对于许多应用，重要的是要在非常紧的空间内，甚至到纳米级（即，厚度比人头发的厚度小约10,000倍）。 此过程称为纳米芬。 在该项目中，将研究纳米限制下的聚合，并将测试理论预测。 这项研究的结果对于对纳米电信和纳米光刻过程中约有聚合的基本了解至关重要，因此可以促进对这些行业重要的技术进步。 此外，结果对了解生物系统中的生物聚合物和蛋白质具有意义，例如，在蛋白质聚合中可以在受限环境中发生。 该项目包括对一名研究生，一名博士后研究员的培训，以及一名涉及纳米级聚合物化学和物理学的尖端研究的本科研究人员。 道德培训将纳入学生的培训中。 PI与少数族裔和女学生合作有很强的往绩，并且将同样努力将代表性不足的学生包括在该项目中。 外展将包括针对TTU计划的两个为期一周的聚合物模块“ Science-这是一个女孩的事”，适用于初中的女孩，以及为4至6年级的TTU Super Sutodays Science计划开发四个两个小时的模块。 技术摘要：解决了将链条限制在纳米孔中的熵损失的基本问题，并且将测试具有链尺寸和纳米填充尺寸和尺寸的限制熵的理论。 将链条限制在纳米孔中的熵损失将取决于纳米结构和散装条件下反应的熵变化的差异。 该研究的重点是纳米组合的自由基N-烷基甲基丙烯酸酯聚合化，因为在大量情况下这些系统的热力学已被充分了解。 将使用量热法研究单体/聚合物平衡，这是反应温度和限制条件的函数，范围从大圆柱孔中的稀释溶液的弱限制到小球腔中未稀释单体的强限制。 单体和引发剂的浓度将改变与孔径大小和反应温度无关的分子量，而孔隙表面化学和单体结构将变化以改变界面相互作用。此外，将与具有与纳米多孔矩阵相似的纳米颗粒填充系统进行比较，但没有链条约束。