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Structural aspects of polyanion and hydrophobically modified polycation multilayers on hydrophilic or hydrophobic surfaces

机译:亲水或疏水表面上的聚阴离子和疏水改性的聚阳离子多层的结构方面

摘要

Multilayer films of carboxymethylcellulose (CMC), a polyanion, and bromide salts of poly(4-vinylpyridine) quaternized with linear aliphatic chains of 2 (ethyl) and 5 (pentyl) carbon atoms, coded as QPVP-C2 and QPVP-C5, respectively, were fabricated by layer-by-layer (LbL) self-assembly onto Si/SiO2 wafers (hydrophilic substrate) or polystyrene, PS, films (hydrophobic substrate). The films were characterized by means of ex situ and in situ ellipsometry, atomic force microscopy (AFM), contact angle measurements and sum frequency generation vibrational spectroscopy (SFG). Antimicrobial tests were used to assess the exposure of pyridinium moieties to the aqueous medium. In situ ellipsometry indicated that for Si/SiO2 the chains were more expanded than the PS films and both substrates systems composed of QPVP-C5 were thicker than those with QPVP-C2. For dried layers, the alkyl side group size had a small effect on the thickness evolution, regardless of the substrate. At pH 2 the multilayers showed high resistance, evidencing that the build-up is driven not only by cooperative polymer-polymer ion pairing, but also by hydrophobic interactions between the alkyl side chains. The LbL films became irregular as the number of depositions increased. After the last deposition, the wettability of QPVP-C2 or QPVP-C5 terminated systems on the Si/SiO2 wafers and PS films were similar, except for QPVP-C2 on Si/SiO2 wafers. Unlike the morphology observed for LbL films on Si/SiO2 wafers, PS induced the formation of porous structures. SFG showed that in air the molecular orientation of pyridinium groups in multilayers with QPVP-C5 was stronger than in those containing QPVP-C2. The exposure of pyridinium moieties to the aqueous medium was more pronounced when the LbL were assembled on Si/SiO2 wafers.
机译:羧甲基纤维素(CMC),聚阴离子和聚(4-乙烯基吡啶)的溴盐多层膜,季铵盐分别带有2个(乙基)和5个(戊基)碳原子的线性脂族链,分别编码为QPVP-C2和QPVP-C5通过在Si / SiO2晶片(亲水性基板)或聚苯乙烯PS膜(疏水性基板)上进行层层(LbL)自组装来制造。通过异位和原位椭偏,原子力显微镜(AFM),接触角测量和总频率产生振动光谱(SFG)对薄膜进行表征。抗菌测试用于评估吡啶部分在水性介质中的暴露。原位椭圆光度法表明,对于Si / SiO2,链比PS膜更膨胀,并且由QPVP-C5组成的两个基底系统都比具有QPVP-C2的基底系统厚。对于干燥的层,无论侧基如何,烷基侧基的大小对厚度的变化影响很小。在pH 2时,多层膜显示出高电阻,这表明堆积不仅是由聚合物-聚合物协同离子配对驱动,而且还受到烷基侧链之间的疏水相互作用的驱动。随着沉积数量的增加,LbL膜变得不规则。在最后一次沉积之后,除了在Si / SiO2晶片上的QPVP-C2以外,在Si / SiO2晶片和PS膜上的QPVP-C2或QPVP-C5终止系统的润湿性相似。与在Si / SiO2晶片上观察到的LbL膜的形态不同,PS诱导了多孔结构的形成。 SFG表明,在空气中带有QPVP-C5的多层中吡啶鎓基团的分子取向要强于含有QPVP-C2的多层中。当将LbL组装在Si / SiO2晶圆上时,吡啶鎓部分暴露于水性介质中更为明显。

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