Surface Stability and Functional Property of Polymerized Langmuir—Blodgett Type Films

Langmuir-Blodgett (LB) type films, showing highly ordered layer structures, were prepared from two types of polymerizable amphiphiles. One type of the amphiphiles has a polymerizable group in a hydrophilic part, dihexadecyl TV-[11-[[2-(acryloyloxy)ethyl]dimethylammonio]undecanoyl]glutamate bromide (2C₁₆-L-Glu-C₁₁N⁺Ac), and the other has a polymerizable group in a hydrophobic part, 3-[[ll-(meth-acryloyloxy)undecyl]dodecylmethylammonio]propanesulfonate (MC₁₁C₁₂NS). The LB type films composed of these amphiphiles were polymerized in order to stabilize the surface chemical structure (hydrophilicity or hydrophobicity). The highly oriented bilayer structures were kept even after polymerization. The surface chemical structure of the built-up film composed of 2C₁₆-L-Glu-C₁₁N⁺Ac was not immobilized by polymerization and the hydrophobic surface changed into the hydrophilic one in water. This result was due to that an intermonolayer polymerization hardly took place. In the case of the LB type films composed of MC₁₁C₁₂NS,the surface chemical structure was stabilized by polymerization and the hydrophilic surface was stable even in air. This result shows that the intermonolayer polymerization progressed in such LB type films. The blood compatibility of the built-up film composed of MC₁₁C₁₂NS which has a sulfonic group in a hydrophilic part was investigated on the basis of the interaction with human blood platelets. The built-up film with sulfonic group orienting normal to the layer surface showed an excellent blood compatibility mainly owing to its negatively charged surface which repels platelets.