Self-healing Polymer Composite Films With Highly Mechanically Stability And Transparency, Fiame-retardant And Superhydrophobic Properties

Self-healing, which is the ability of living creatures to recover damage whenever andwherever it occurs, has gained particular interest of scientists in recent years. Many effortshave been made to impart self-healing ability to artificial materials to enlongate their lifetimeand decrease the maintenance cost. Compared with seld-healing materials that can healstructure damage, those materials capable of restoring functions are more important forpractical applications. Layer-by-Layer (LbL) assembly technique has been widely used tofabricate various kinds of functional films on solid substrates since it was rediscovered byDecher and co-workers in early1990s. Studies in our groups have demonstrated that the LbLassembly is promising in fabricating both extrinsic and intrinsic self-healing films, such asself-healing conductive and self-healing superhydrophobic films. In this dissertation, twokinds of self-healing coatings have been fabricated using LbL assembly:(1) Branched polyethleneimine (bPEI) and poly(acrylic acid)(PAA) were alternatelydeposited to fabricate self-healing transparent bPEI/PAA films. Small molecular weightpolyelectrolytes of PAA and bPEI were mixed into the corresponding high molecular weightpolyelectrolytes to enhance the chain mobility of the LbL assembly bPEI/PAA films. Afterannealing the as-prepared bPEI/PAA film in aquous NaCl solution, their surface becomeextremely smooth, leading to bPEI/PAA films of highly optical transparent. Then CaCO3nanoparticles were introduced into the annealed bPEI/PAA films to enhance their mechanicalrobustness without producing any negative influence on their self-healing ability. In this way,self-healing transparent films with high Young’s modulus and hardness were obtained. Cutswith widths and depths of several tens of micrometers on these films can be convenientlyhealed by immersing the films in water.(2) Flame-retardant fabric was fabricated by alternately depositing ammonium phosphate (APP) and bPEI on cotton. Based on the thiol-ene click reaction, fluorinated POSS(F-POSS) was synthesized by grafting the vinylPOSS with perfluorodecanethiol under UVlight irradiation. The flame-retardant fabric was immersed in the F-POSS suspension to gainsuperhydrophobicity. As a result, self-healing superhydrophobic fabric with flame-retardancywas obtained. The damaged superhydrophobicility on the fabric can be healed for more than10times by leaving the fabric under ambient environment with slight humidity.