Kiriy Anton, Gorodyska Ganna, Minko Sergiy, Jaeger Werner, Stepánek Petr, Stamm Manfred
Institut für Polymerforschung Dresden, Hohe Strasse 6, Germany.
J Am Chem Soc. 2002 Nov 13;124(45):13454-62. doi: 10.1021/ja0261168.
We show that hydrophobic flexible polyelectrolyte molecules of poly(2-vinylpyridine) and poly(methacryloyloxyethyl dimethylbenzylammonium chloride) are trapped and frozen due to adsorption on the mica surface, and the observed AFM single molecule structures reflect the molecular conformation in solution. An increase of the ionic strength of the solution induces the cascade of abrupt conformational transitions due to the intrachain segregation from elongated coil to compact globule conformations through intermediate pearl necklace-globule conformations with different amounts of beads per chain. The length of the necklaces and the number of beads decrease, while the diameter of beads increases with the increase of ionic strength. Coexistence at the same time of extended coils, necklaces with different amounts of beads, and compact globules indicates the cascade of the first-order-type phase transitions.
我们表明，聚（2-乙烯基吡啶）和聚（甲基丙烯酰氧基乙基二甲基苄基氯化铵）的疏水性柔性聚电解质分子由于吸附在云母表面而被捕获并冻结，并且观察到的原子力显微镜单分子结构反映了溶液中的分子构象。溶液离子强度的增加会导致级联的突然构象转变，这是由于链内从伸长的线圈构象通过具有不同每条链珠子数量的中间珍珠项链-球状体构象分离为紧密的球状体构象。随着离子强度的增加，项链的长度和珠子的数量减少，而珠子的直径增加。伸展的线圈、具有不同珠子数量的项链和紧密球状体同时共存表明了一级相变的级联。
