Greene Anna C, Zhu Jiahua, Pochan Darrin J, Jia Xinqiao, Kiick Kristi L
Department of Materials Science and Engineering, University of Delaware, 201 DuPont Hall, Newark, DE, 19716, and Delaware Biotechnology Institute, 15 Innovation Way, Newark, DE 19711.
Macromolecules. 2011 Mar 4;44(7):1942-1951. doi: 10.1021/ma102869y.
In order to expand the utility of current polymeric micellar systems, we have developed amphiphilic multiblock copolymers containing alternating blocks of poly(acrylic acid) and poly(styrene). Heterotelechelic poly(tert-butyl acrylate-b-styrene) diblock copolymers containing an α-alkyne and an ω-azide were synthesized by atom transfer radical polymerization (ATRP), allowing control over the molecular weight while maintaining narrow polydispersity indices. The multiblock copolymers were constructed by copper-catalyzed azide-alkyne cycloaddition of azide-alkyne end functional diblock copolymers which were then characterized by (1)H NMR, FT-IR and SEC. The tert-butyl moieties of the poly(tert-butyl acrylate-b-styrene) multiblock copolymers were easily removed to form the poly(acrylic acid-b-styrene) multiblock copolymer ((PAA-PS)(9)), which contained up to 9 diblock repeats. The amphiphilic multiblock (PAA-PS)(9) (M(n) = 73.3 kg/mol) was self-assembled by dissolution into tetrahydrofuran and extensive dialysis against deionized water for 4 days. The critical micelle concentration (CMC) for (PAA-PS)(9) was determined by fluorescence spectroscopy using pyrene as a fluorescent probe and was found to be very low at 2 × 10(-4) mg/mL. The (PAA-PS)(9) multiblock was also analyzed by dynamic light scattering (DLS) and transmission electron microscopy (TEM). The hydrodynamic diameter of the particles was found to be 11 nm. Discrete spherical particles were observed by TEM with an average particle diameter of 14 nm. The poly(acrylic acid) periphery of the spherical particles should allow for future conjugation of biomolecules.
为了拓展当前聚合物胶束系统的应用范围，我们合成了包含聚丙烯酸和聚苯乙烯交替嵌段的两亲性多嵌段共聚物。通过原子转移自由基聚合（ATRP）合成了含有α-炔基和ω-叠氮基的杂臂端基聚（丙烯酸叔丁酯-b-苯乙烯）二嵌段共聚物，从而在保持窄多分散指数的同时控制分子量。多嵌段共聚物通过叠氮基-炔基端基功能化二嵌段共聚物的铜催化叠氮-炔环加成反应构建而成，随后通过（1）H NMR、FT-IR和SEC进行表征。聚（丙烯酸叔丁酯-b-苯乙烯）多嵌段共聚物的叔丁基部分易于去除，从而形成含有多达9个二嵌段重复单元的聚（丙烯酸-b-苯乙烯）多嵌段共聚物（（PAA-PS）（9））。两亲性多嵌段共聚物（PAA-PS）（9）（M（n）= 73.3 kg/mol）通过溶解在四氢呋喃中并对去离子水进行4天的广泛透析进行自组装。使用芘作为荧光探针通过荧光光谱法测定了（PAA-PS）（9）的临界胶束浓度（CMC），发现其非常低，为2×10^（-4）mg/mL。还通过动态光散射（DLS）和透射电子显微镜（TEM）对（PAA-PS）（9）多嵌段共聚物进行了分析。发现颗粒的流体力学直径为11 nm。通过TEM观察到离散的球形颗粒，平均粒径为14 nm。球形颗粒的聚丙烯酸外围应允许未来生物分子的缀合。
