Inkjet printing of insoluble biopolymer and polymer complexes
Inkjet printing of a dilute polymer solution leads to pancakes, lines or films of dried polymer with a thickness of about 100nm. Sequential printing two inks, one a soluble cationic polymer and one a soluble anionic polymer leads to the formation of an insoluble complex, similar to that formed by ionic self-assembly using sequential dipping processes. Multiple alternating layers of polyglutamic acid and polylysine are printed as a pattern of lines on glass and then are annealed in a humid atmosphere for up to one day. this annealing allows interdiffusion of the polymers and complex formation. The process is followed by measuring solubility, by confocal microscopy of the layers and by EDS analysis of the ions remaining after the lines are washed. Similar complex formation is seen with combinations of other charged polymers and with combinations of nanoparticulate pigments and polymers.