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.

非技术总结：用于制造聚合物材料的化学过程称为聚合。 对于许多应用来说，重要的是在极其紧密的空间内制造这种聚合物材料，甚至低至纳米级（即，低至比人头发的厚度小约10，000倍的厚度）。 这个过程被称为纳米限制。 在这个项目中，将研究纳米约束下的聚合，并测试理论预测。 研究结果对于从根本上了解纳米电子和纳米光刻工艺中的受限聚合非常重要，因此可以促进对这些行业至关重要的技术进步。 此外，这些结果对理解生物系统中的生物聚合物和蛋白质具有影响，例如，蛋白质聚合可以发生在封闭的环境中。 该项目包括培训一名研究生、一名博士后研究员和一名本科生研究员，从事涉及纳米级聚合物化学和物理的前沿研究。 道德操守培训将纳入对学生的培训。 PI在与少数民族学生和女学生合作方面有着良好的记录，同样将积极努力将代表性不足的学生纳入该项目。 外联活动将包括为TTU方案组织两个为期一周的聚合物模块，“科学-这是女孩的事”，供初中女孩使用，并为TTU超级星期六科学方案为四至六年级学生开发四个两小时的模块。 技术概述：解决了将链限制在纳米孔上的熵损失的基本问题，并且将测试限制熵与链大小和纳米限制大小和尺寸的缩放的理论。 将链限制到纳米孔的熵损失将直接由纳米限制和本体条件下反应的熵变的差异确定。 研究的重点是纳米限制的自由基甲基丙烯酸正烷基酯聚合，因为这些系统在散装情况下的热力学很好地理解。 将使用量热法作为反应温度和限制条件的函数来研究聚合物/聚合物平衡，范围从大圆柱孔中的稀溶液的弱限制到小球形腔中的未稀释单体的强限制。 将改变单体和引发剂浓度以改变分子量，而与孔径和反应温度无关，而将改变孔表面化学和单体结构以改变界面相互作用。此外，比较将与纳米颗粒填充的系统具有类似的表面体积比的纳米多孔矩阵，但没有链限制的约束。