Tapia M J, Burrows H D, Valente A J M, Pradhan S, Scherf U, Lobo V M M, Pina J, Seixas de Melo J
Departamento de Química, Universidad de Burgos, Plaza Misael Bañuelos s/n, Burgos 09001, Spain.
J Phys Chem B. 2005 Oct 20;109(41):19108-15. doi: 10.1021/jp052233o.
The interaction has been studied in aqueous solutions between a negatively charged conjugated polyelectrolyte poly{1,4-phenylene-[9,9-bis(4-phenoxybutylsulfonate)]fluorene-2,7-diyl} copolymer (PBS-PFP) and several cationic tetraalkylammonium surfactants with different structures (alkyl chain length, counterion, or double alkyl chain), with tetramethylammonium cations and with the anionic surfactant sodium dodecyl sulfate (SDS) by electronic absorption and emission spectroscopy and by conductivity measurements. The results are compared with those previously obtained on the interaction of the same polymer with the nonionic surfactant C12E5. The nature of the electrostatic or hydrophobic polymer-surfactant interactions leads to very different behavior. The polymer induces the aggregation with the cationic surfactants at concentrations well below the critical micelle concentration, while this is inhibited with the anionic SDS, as demonstrated from conductivity measurements. The interaction with cationic surfactants only shows a small dependence on alkyl chain length or counterion and is suggested to be dominated by electrostatic interactions. In contrast to previous studies with the nonionic C12E5, both the cationic and the anionic surfactants quench the PBS-PFP emission intensity, leading also to a decrease in the polymer emission lifetime. However, the interaction with these cationic surfactants leads to the appearance of a new emission band (approximately 525 nm), which may be due to energy hopping to defect sites due to the increase of PBS-PFP interchain interaction favored by charge neutralization of the anionic polymer by cationic surfactant and by hydrophobic interactions involving the surfactant alkyl chains, since the same green band is not observed by adding either tetramethylammonium hydroxide or chloride. This effect suggests that the cationic surfactants are changing the nature of PBS-PFP aggregates. The nature of the polymer and surfactant interactions can, thus, be used to control the spectroscopic and conductivity properties of the polymer, which may have implications in its applications.
通过电子吸收光谱、发射光谱和电导率测量，研究了带负电荷的共轭聚电解质聚{1,4-亚苯基-[9,9-双(4-苯氧基丁基磺酸盐)]芴-2,7-二基}共聚物（PBS-PFP）与几种具有不同结构（烷基链长度、抗衡离子或双烷基链）的阳离子四烷基铵表面活性剂、四甲基铵阳离子以及阴离子表面活性剂十二烷基硫酸钠（SDS）在水溶液中的相互作用。将结果与之前关于该聚合物与非离子表面活性剂C12E5相互作用的研究结果进行了比较。静电或疏水聚合物-表面活性剂相互作用的性质导致了非常不同的行为。从电导率测量结果可以看出，聚合物在远低于临界胶束浓度的浓度下就能诱导与阳离子表面活性剂发生聚集，而与阴离子SDS的聚集则受到抑制。与阳离子表面活性剂的相互作用仅对烷基链长度或抗衡离子有较小的依赖性，推测主要由静电相互作用主导。与之前对非离子C12E5的研究不同，阳离子和阴离子表面活性剂都会淬灭PBS-PFP的发射强度，导致聚合物发射寿命也缩短。然而，与这些阳离子表面活性剂的相互作用会导致出现一个新的发射带（约525nm），这可能是由于阳离子表面活性剂对阴离子聚合物的电荷中和以及涉及表面活性剂烷基链的疏水相互作用有利于PBS-PFP链间相互作用的增加，从而使能量跳跃到缺陷位点，因为加入氢氧化四甲基铵或氯化四甲基铵时未观察到相同的绿色带。这种效应表明阳离子表面活性剂正在改变PBS-PFP聚集体的性质。因此，聚合物和表面活性剂相互作用的性质可用于控制聚合物的光谱和电导率性质，这可能对其应用有影响。
