Electrostatic Patterns on Surfactant Coatings Change with Ambient Humidity

被引:13
作者
Bernardes, Juliana Silva [1 ]
Rezende, Camila Alves [1 ]
Galembeck, Fernando [1 ]
机构
[1] Univ Estadual Campinas, Inst Chem, BR-13084971 Campinas, SP, Brazil
基金
巴西圣保罗研究基金会;
关键词
DEWETTING PATTERNS; FORCE MICROSCOPY; LATEX-PARTICLES; INTERFACES; CHARGE; FILMS; ORGANIZATION; BUILDUP; WATER; AFM;
D O I
10.1021/jp107291j
中图分类号
O64 [物理化学(理论化学)、化学物理学];
学科分类号
070304 ; 081704 ;
摘要
Sodium dodecyl sulfate (SDS) deposited by dewetting on mica under well-defined experimental conditions presents patterns with characteristic morphology and electric potential distribution, These are formed by surfactant steps and terraces, with more negative potential on the steps than on the terrace surfaces. Kelvin force microscopy results show that the electric potential on the sample surfaces becomes more negative just by increasing the atmospheric relative humidity from 30 to 70%, within a grounded and shielded environment. The kinetic effect of the potential variation was also evaluated by keeping the sample at the same humidity for short (2 h) and longer times (24 h). In the last case, the electric potentials changed to more negative values, nonreversibly. Changes on the surface electric patterns are not paralleled by morphological changes in the lamellar structure, since no significant variations in the topography are observed. It is also interesting to note that, despite the persistent negative potential values acquired under high humidity conditions, the potential difference between each terrace surface and its neighboring step is constant and within a narrow range (60-100 mV), indicating that the negative charge is uniformly distributed throughout the crystal.
引用
收藏
页码:19016 / 19023
页数:8
相关论文
共 36 条
[1]  
AFSARSIDDIQUI AB, 2004, K LONGMAR, V20, P7575
[2]   Topography and surface potential in Kelvin force microscopy of perfluoroalkyl alkanes self-assemblies [J].
Alexander, John ;
Magonov, Sergei ;
Moeller, Martin .
JOURNAL OF VACUUM SCIENCE & TECHNOLOGY B, 2009, 27 (02) :903-911
[3]  
ATKINS PW, 1994, PHYSICAL CHEM, P840
[4]   The surface of neat water is basic [J].
Beattie, James K. ;
Djerdjev, Alex N. ;
Warr, Gregory G. .
FARADAY DISCUSSIONS, 2009, 141 :31-39
[5]  
BERNARDES JS, 2006, CHEM, V110, P23433
[6]   Morphology and Self-Arraying of SDS and DTAB Dried on Mica Surface [J].
Bernardes, Juliana S. ;
Rezende, Camila A. ;
Galembeck, Fernando .
LANGMUIR, 2010, 26 (11) :7824-7832
[7]   Scanning electric potential microscopy imaging of polymer latex films: Detection of supramolecular domains with nonuniform electrical characteristics [J].
Braga, M ;
Costa, CAR ;
Leite, CAP ;
Galembeck, F .
JOURNAL OF PHYSICAL CHEMISTRY B, 2001, 105 (15) :3005-3011
[8]   Films driven by surface tension gradients [J].
Cachile, M ;
Schneemilch, M ;
Hamraoui, A ;
Cazabat, AM .
ADVANCES IN COLLOID AND INTERFACE SCIENCE, 2002, 96 (1-3) :59-74
[9]  
Cardoso AH, 1999, LANGMUIR, V15, P4447
[10]  
Cardoso AH, 1998, LANGMUIR, V14, P3187