Javakhishvili Irakli, Hvilsted Søren
Technical University of Denmark, Department of Chemical and Biochemical Engineering, Danish Polymer Centre, Building 423, DK-2800 Kgs. Lyngby, Denmark.
Biomacromolecules. 2009 Jan 12;10(1):74-81. doi: 10.1021/bm800860t.
Amphiphilic poly(epsilon-caprolactone)-b-poly(acrylic acid) (HS-PCL-b-PAA) with a thiol functionality in the PCL terminal has been prepared in a novel synthetic cascade. Initially, living anionic ring-opening polymerization (ROP) of epsilon-caprolactone (epsilon-CL) employing the difunctional initiator, 2-hydroxyethyl 2-bromoisobutyrate, followed by esterification with 2,4-dinitrophenyl- or 4-monomethoxytrityl-protected mercaptoacetic acids (Prot-), provided well-defined PCL macroinitiators capped with protected thiols. The macroinitiators allowed atom transfer radical polymerization (ATRP) of tert-butyl acrylate (tBA) in a controlled fashion by use of NiBr2(PPh3)2 catalyst to produce Prot-PCL-b-PtBA with narrow polydispersities (1.17-1.39). Subsequent mild deprotection protocols provided HS-PCL-b-PAA. Reduction of a gold salt in the presence of this macroligand under thiol-deficient conditions afforded stable, aggregation-free nanoparticles, as evidenced from UV-vis spectroscopy and transmission electron microscopy (TEM), the latter revealed nanoparticles with a mean diameter of 9.0+/-3.1 nm.
通过一种新型合成级联反应制备了在聚己内酯（PCL）末端具有硫醇官能团的两亲性聚（ε-己内酯）-b-聚（丙烯酸）（HS-PCL-b-PAA）。首先，使用双官能引发剂2-溴异丁酸2-羟乙酯对ε-己内酯（ε-CL）进行活性阴离子开环聚合（ROP），然后与2,4-二硝基苯基或4-单甲氧基三苯甲基保护的巯基乙酸（Prot-）进行酯化反应，得到末端带有保护硫醇的结构明确的PCL大分子引发剂。这些大分子引发剂通过使用NiBr2(PPh3)2催化剂以可控方式引发丙烯酸叔丁酯（tBA）的原子转移自由基聚合（ATRP），从而制备出具有窄多分散性（1.17 - 1.39）的Prot-PCL-b-PtBA。随后通过温和的脱保护方案得到HS-PCL-b-PAA。在硫醇缺乏的条件下，在这种大环配体存在下还原金盐可得到稳定的、无聚集的纳米颗粒，紫外可见光谱和透射电子显微镜（TEM）证明了这一点，后者显示纳米颗粒的平均直径为9.0±3.1 nm。
