Influence of the Interaction Strength between Supramolecular Complexes on the Topography of Neutral Polymer Multilayer Films

详细信息    查看全文

• 作者：Lydie S茅on ; Audrey Parat ; Fabien Gaudi猫re ; Jean-Claude Voegel ; Rachel Auz茅ly-Velty ; Philippe Lorchat ; Liliane Coche-Gu茅rente ; Bernard Senger ; Pierre Schaaf ; Lo茂c Jierry ; Fouzia Boulmedais
• 刊名：Langmuir
• 出版年：2014
• 出版时间：June 10, 2014
• 年：2014
• 卷：30
• 期：22
• 页码：6479-6488
• 全文大小：597K
• 年卷期：v.30,no.22(June 10, 2014)
• ISSN：1520-5827

文摘

Step-by-step polymer film buildup processes lead to polymer coatings, e.g., polyelectrolyte multilayers, of various structures ranging from continuous smooth films to droplet like discontinuous coatings. Yet, the origin of these different behaviors depending upon the system is not yet known. This study is a first attempt to rationalize the evolution of the coating structure as a function of the strength of the interactions between the polymers constituting the film. We investigated the influence of the strength of noncovalent host鈥揼uest interactions between cyclodextrin (CD) and pyrene (Py), ferrocene (Fc) or adamantane (Ad) on the structure of neutral poly(N-hydroxypropylmethacrylamide) (PHPMA) multilayers films formed in a step-by-step manner. In solution, the strength of the inclusion complex (measured by log K where K is the complex association constant) is increasing in the order Py/尾-CD < Fc/尾-CD < Ad/尾-CD and can be further varied in the presence of different sodium salts at different ionic strengths. Depending upon this strength, the buildup process is limited to the formation of isolated aggregates for PHPMA-CD/PHPMA-Py, leading to smooth continuous films for PHPMA-CD/PHPMA-Fc and to droplet-like films, not entirely covering the substrate, for PHPMA-CD/PHPMA-Ad. To study the influence of the strength of the host鈥揼uest interactions on the film topography, PHPMA-CD/PHPMA-Fc films were built in the presence of different sodium salts at different ionic strengths. For low host鈥揼uest interactions, only isolated aggregates are formed on the substrate. As the strength of the host鈥揼uest interactions increases (increase of log K), the formed films go through a droplet-like structure, before becoming continuous but rough for stronger interactions. When the interaction strength is further increased, the roughness of the films decreases, leading to a smooth continuous film before becoming rough again at still higher interaction strength. Smooth continuous multilayers seem thus to be obtained for an optimal range of the interaction strength.