Self-Assembly of Highly Immiscible Polymers Using Balanced Surfactants

使用平衡表面活性剂进行高度不相容聚合物的自组装PI的目标是创建一个表面活性剂库，用于控制高度不相容聚合物混合物中的纳米级自组装。这将使新的纳米结构聚合物材料的创造成为可能。它还可以重新利用混合的聚合物废物。所提出的方法与该领域以往大量的实验和理论工作不同，这些工作依赖于A-B共聚物的表面性质来组织A和B均聚物的混合物。现在人们认识到，只有当均聚物弱不相容时，这些类型的共聚物才能组织界面。将在研究中使用的表面活性剂是一种平衡的A-C嵌段共聚物。平衡的概念取自关于水体系中表面作用的丰富文献。非离子表面活性剂具有疏水和亲水平衡的特性，尽管它们具有高度的不相容性，但仍成功地在油/水混合物中创建了纳米结构。我们的目标是将这一原理应用于聚合物。拟议的实验将在高度不相容的聚烯烃、聚丁烯(PB)和聚异丁烯(PIB)的混合物上进行。PI将使用聚丁烯-嵌段-头对头聚丙烯(PB-PP)共聚物作为表面活性剂。其目的是证明PB/PIB/PB-PP共混物表现出水体系中丰富的自组装特性。PI之所以选择这个体系，是因为PB/PP和PIB/PP的Flory-Huggins相互作用参数的温度依赖性的大小和符号分别(近似)相等和相反。本研究所需的模型聚合物将通过阴离子聚合和阳离子聚合来合成。自组装将通过小角中子散射、光散射和电子显微镜进行研究。IMPACT声明：这项关于平衡表面活性剂的研究有可能引入全新的技术来控制聚合物共混物的形态。它将能够从聚异丁烯等具有工业重要性的聚合物中创造出新的混合材料(一种目前具有相当重要意义的聚合物，因为它用于制造在化学和生物污染地区工作的防护服)。这项拟议的研究也可能使导电和非导电聚合物纳米结构混合物的工业化生产成为可能。平衡表面活性剂的使用方法是受到合成表面活性剂和天然表面活性剂在水体系中的功效的启发。然而，由于基本分子间相互作用的差异，将在水体系中学到的原理应用于烃类聚合物的科学挑战是相当大的。与水分子的相互作用主要受其永久偶极和特定相互作用的影响，如氢键。SGER的提案试图探索在没有这些相互作用的情况下设计平衡表面活性剂的可能性。

SELF-ASSEMBLY OF HIGHLY IMMISCIBLE POLYMERS USING BALANCED SURFACTANTSThe PI's objective is to create a library of surfactants for controlling the nano-scale self-assembly in mixtures of highly immiscible polymers. This will enable the creation of new nano-structuredpolymer materials. It may also enable reusing commingled polymeric waste. The proposed approach represents a risky departure from the large body of previous experimental and theoretical work in this field which relied of the surfactancy of A-B copolymers for organizing mixtures of A and B homopolymers. It is now recognized that these types of copolymers can only organize interfaces if the homopolymers are weakly immiscible. The surfactant that will be uses in the study is a balanced A-C block copolymer. The notion of balance is adapted from the rich literature on surfactancy in aqueous systems. Nonionic surfactants with balanced hydrophobic and hydrophilic character have been successful in creating nano-scale organization in oil/water mixtures in spite of their high degree of incompatibility. The goal is to apply this principle to polymers. The proposed experiments will be conducted on mixtures of highly immiscible polyolefins, polybutene (PB) and polyisobutylene (PIB). The PI will use a polybutene-block-head-to-head polypropylene (PB-PP) copolymer as a surfactant. The objective is to demonstrate that PB/PIB/PB-PP blends exhibit the rich self-assembly characteristics found in aqueous systems. The PI chose this system because the magnitude and sign of the temperature dependence of the PB/PP and PIB/PP Flory-Huggins interaction parameters are (approximately) equal and opposite, respectively. Model polymers required for this study will be synthesized by anionic and cationic polymerization. Self-assembly will be studied by small angle neutron scattering, light scattering, and electron microscopy.IMPACT STATEMENTThis proposed research on balanced surfactants holds the potential of introducing radically new technology for controlling the morphology of polymer blends. It will enable the creation of new blended materials from industrially important polymers such as polyisobutylene (a polymer of considerable current importance because of its use in the manufacture protective garments for working in chemically and biologically contaminated areas). Industrial production of nanostructured blends of electrically conducting and non-conducting polymers may also be enabled by the proposed research. The approach of using balanced surfactants is inspired by the efficacy of synthetic and natural surfactants in aqueous systems. However, the scientific challenge of applying principles learned in aqueous systems to hydrocarbon polymers is considerable because of the difference in fundamental intermolecular interactions. Interactions with water molecules are dominated by their permanent dipole and specific interactions such as hydrogen bonding. The SGER proposal seeks to explore the possibility of designing balanced surfactants in the absence of these interactions.