New Block and Gradient Copolymers by Controlled/Living Radical Polymerization

本项目的目的是合成和表征用可控自由基聚合法制备的新型嵌段和梯度共聚物。嵌段共聚物和梯度共聚物倾向于微相分离，可以形成各种周期性和连续的纳米结构。将制备并表征三组共聚物。它们包括可能具有良好粘附性能的丙烯酸甲酯（BA）和甲基丙烯酸甲酯（MMA）组成的共聚物，研究用于表面活性剂的两亲性嵌段和可能用作共混添加剂的末端功能聚合物。通过精确控制共聚物链的尺寸、组成和功能，可以制备出各种嵌段和梯度共聚物。BA/MMA共聚物的初步研究结果表明，外嵌段含有梯度结构的嵌段与纯三嵌段的力学性能有显著差异。各种二嵌段和三嵌段共聚物将被制备，其中的总体组成、分子量和沿链的序列分布将会变化。此外，还将研究聚分散性和梯度分布对共聚物力学性能和热性能的影响，以便得出所得聚合物的结构-性能相关性。由聚苯乙烯（PS）和聚丙烯酸（PA）组成的表面活性剂的初步结果表明，通过控制和系统地改变聚合物链的组成和拓扑结构，可以设计表面活性剂，并将共聚物结构（AS， ASA， SAS，三官能团SA）与其表面活性剂性能联系起来。该研究的扩展将包括制备含有随机和/或梯度疏水段和非离子表面活性剂的新型两亲体，并探索这些变化对传统乳剂和水性ATRP稳定性的影响。最终项目将包括制备端功能共聚物并评估其作为共混添加剂的功效。将进行嵌段、随机和梯度共聚物的比较研究。预计通过对嵌段和梯度共聚物结构的精确控制和系统变化，将有可能了解和预测结构变化如何影响目标材料的热、力学和其他性能。更高效的粘合剂、弹性体、表面活性剂和共混添加剂可以基于这种结构-性能相关性开发出来

The goal of this project is to synthesize and characterize new block and gradient copolymers prepared by controlled radical polymerization methods. Block and gradient copolymers tend to microphase separate and may form various periodic and continuous nanostructures. Three groups of copolymers will be prepared and characterized. They include copolymers composed of a-butyl acrylate (BA) and methyl methacrylate (MMA) which may have good adhesive properties, amphiphilic blocks for study as surfactants and end-functional polymers for potential use as blend additives. Various block and gradient copolymers will be made by precisely controlling the dimension, composition and functionality in the copolymer chains. Preliminary results on the BA/MMA copolymers indicate that the mechanical properties of the blocks containing a gradient structure in the outer blocks are dramatically different from the pure triblocks. Various di- and triblock copolymers will be prepared in which the overall composition, molecular weight and sequence distribution along the chain will be varied. In addition, the effect of the polydispersity and the gradient distribution on the mechanical and thermal properties of the copolymers will be studied in order to draw a structure-property correlation for the obtained polymers. Preliminary results for the surfactants composed of polystyrene (PS) and poly(acrylic acid) (PA) demonstrated that by controlling and systematically varying the composition and topology of the polymer chains, it was possible to design surfactants and to correlate the copolymer structure (AS, ASA, SAS, trifunctional SA) with its surfactant properties. Extension of this study will include the preparation of new amphiphiles containing a random and/or gradient hydrophobic segment and non-ionic surfactants and probing the effects of the alterations on the stability of conventional emulsions and water-borne ATRP. The final project will involve preparing end-functional copolymers and evaluating their efficacy as blend additives. A comparative study of block, random and gradient copolymers will be performed.%%%It is anticipated that through precise control and systematic variation of the structure of block and gradient copolymers, it will be possible to understand and predict how structural variations affect the thermal, mechanical and other properties of the targeted materials. More efficient adhesives, elastomers, surfactants and blend additives may be developed based on this type of structure-property correlation.***