Directed Nano-Patterning of Polymer Nanocomposite Thin Films

Download or read book Directed Nano-Patterning of Polymer Nanocomposite Thin Films written by Xiaoteng Wang and published by . This book was released on 2016 with total page 75 pages. Available in PDF, EPUB and Kindle. Book excerpt: Polymer-nanoparticle (NP) composites have been studied extensively as a core material that exhibits advantageous optical, electrical and mechanical properties in nanotechnology. It has been well-established that a specific distribution state of nanoparticles in a polymer matrix is the key issue to optimize a desired polymer nanocomposite (PNC) property. However effective way of controlling the spatial distribution of nanoparticles is still a recurring challenge. Here we demonstrated facile processing approach to fabricate nanocomposite thin films with controlled nanoparticle dispersion state by exploiting the entropic interactions, thereby controlling the macroscopic performance of the material. The interactions of nanoparticles with polymers are mediated by the ligands attached to the nanoparticles. Location and dispersion of polystyrene grafted titanium dioxide (PS-g-TiO2) and hydroxyl-functionalized polyhedral oligomeric silsesquioxanes (DPOSS) molecular nanoparticles in homopolymer matrices under various annealing conditions were investigated. PS-g-TiO2 NP filled low molecular weight polystyrene thin films were thermally annealed under nanoscale pattern confinement, which was fabricated by imprinting digital recording media discs (DVD) pattern onto polydimethylsiloxane (PDMS). The NP dispersion changed from randomly distributed to aggregating at the elevated regions of the imprinted films due to the entropic interaction caused by the size difference between the particles and the matrix chains. DPOSS-PS is a type of giant shape amphiphiles which are built up by covalent bonding of molecular nanoparticles. When added to low molecular weight homopolymer matrices, DPOSS-PS nanoparticles exhibited better dispersion in PMMA than in PS matrix. Additionally, to understand the morphology transition and phase separation kinetics, various loading fraction of DPOSS-PS were incorporated into PMMA matrix. Phase separation at multiple length scales was observed when the composition of DPOSS-PS is in the range of 5% and 70%.