Effect of pH on the preparation of self-assembled films of poly(o-ethoxyaniline) and sulfonated lignin

Self-assembled films of Poly(o-ethoxyaniline) (POEA) doped with HCl alternated with sulfonated lignin (SL) were successfully produced under different pHs and their kinetics of formation studied. The adsorption at lower pHs is faster due to the greater electrostatic attraction between the POEA and the SL covered substrate, but a lower amount of POEA is deposited due to charge repulsion of additional POEA chains and conformational steric hindrance. At higher pHs the adsorption of POEA takes longer but it is greater due to the contribution of hydrogen bonding interactions, lower charge repulsion between POEA chains and a more compact polymer conformation. Adsorption of POEA/SL multilayers could be carried out in different types of substrates. Atomic force microscopy (AFM) employed to investigate the morphology of the alternated layers showed that POEA layers exhibited a granular rough aspect, while SL layers presented a much smoother surface.

[1]  Arthur J. Epstein,et al.  Secondary doping in polyaniline , 1995 .

[2]  O. Ikkala,et al.  Processible polyaniline complexes due to molecular recognition: Supramolecular structures based on hydrogen bonding and phenyl stacking , 1997 .

[3]  C. Helm,et al.  Molecular Mechanisms Controlling the Self-Assembly Process of Polyelectrolyte Multilayers , 1998 .

[4]  M. Rubner,et al.  Molecular-Level Processing of Conjugated Polymers. 4. Layer-by-Layer Manipulation of Polyaniline via Hydrogen-Bonding Interactions , 1997 .

[5]  A. MacDiarmid,et al.  Atomic force microscopy surface morphology studies of ‘in situ’ deposited polyaniline thin films , 1995 .

[6]  L. Mattoso,et al.  Kinetics of adsorption of self-assembled films from doped poly(o-ethoxyaniline) , 1997 .

[7]  R. L. Elsenbaumer,et al.  Handbook of conducting polymers , 1986 .

[8]  K. Radotić,et al.  A study of lignin formation at the molecular level by scanning tunneling microscopy. , 1994, Biophysical journal.

[9]  A. Epstein,et al.  Controlled synthesis of high molecular weight polyaniline and poly(o-methoxyaniline) , 1994 .

[10]  A. Epstein,et al.  The concept of secondary doping as applied to polyaniline , 1994 .

[11]  A. Epstein,et al.  Studies on the Chemical Syntheses and on the Characteristics of Polyaniline Derivatives , 1995 .

[12]  O. Ikkala,et al.  On the molecular recognition and associations between electrically conducting polyaniline and solvents , 1995 .

[13]  O. N. Oliveira,et al.  Non-Equilibrium Adsorbed Polymer Layers via Hydrogen Bonding , 1999 .

[14]  Helmuth Möhwald,et al.  Assembly, structural characterization, and thermal behavior of layer-by-layer deposited ultrathin films of poly(vinyl sulfate) and poly(allylamine) , 1993 .

[15]  Gero Decher,et al.  Fuzzy Nanoassemblies: Toward Layered Polymeric Multicomposites , 1997 .

[16]  T. Porter.  Surface morphology of evaporated polyaniline thin films , 1993 .