Inkjet printing of 3D nano-composites formed by photopolymerization of an acrylate monomer

Abstract

This paper considers inkjet printing of optical quality 3D nano-composites from diethylene-glycol diacrylate monomer (DEGDA) containing ZrO 2 nanoparticles at varying concentrations. One application for the composites is for gradient refractive index (GRIN) lenses. The process involves printing of a nanoparticle loaded monomer "ink" onto a substrate and then photopolymerizing the monomer layer by layer using UV light. The results of the study confirm that the presence of nanoparticles favorably affects the reaction kinetics. The reaction rate and chemical conversion are enhanced considerably by the nanoparticles. A seamless interface between the layers, which are 20 m thick, may be achieved if the conversion level of the layer onto which ink is deposited is limited at 60 to 80 %. Dynamic mechanical analysis (DMA) data indicate that both the glass transition and sub Tg viscoelastic properties are influenced by the nanoparticles. When nanoparticles are introduced the Tg relaxation shifts to lower temperatures and a sub Tg relaxation appears whose intensity increases with particle concentration. These results are consistent with a molecular confinement model involving a lower crosslink density rubbery layer at the polymer-particle interfaces.

Effects of nanoparticles on photopolymerization of acrylate monomers in forming nano-composites

“…The acrylates are diethylene glycol diacrylate and isobornyl acrylate. We use these data to determine the appropriate light exposure to form nano-composites with optimal physical, mechanical, and optical properties as detailed elsewhere [7].…”

“…We have observed similar effects of silane 'sizings' on reaction conversions of unsaturated polyesters in the curing of glass-fiber reinforced composites. In our nano-composite systems we have very large dispersed particle surface areas in contact with the monomer [7]. The limiting conversion levels achieved in these experiments is governed by vitrification.…”

A New Approach to Micromachining: High-Precision and Innovative Additive Manufacturing Solutions Based on Photopolymerization Technology

“…The nozzle's size must, however, remain larger than the diameter of the particles in ink to prevent it from clogging. This limits the resolution of elements to the micrometric level [43].…”

Formulation of a Ceramic Ink for 3D Inkjet Printing

“…In conventionally manufactured electronics, thermally conductive but electrically insulating ceramic materials or polymer ceramic composites are state of the art in terms of excess heat dissipation [ 20 , 21 , 22 ]. Similarly, the addition of particulate ceramics to UV or thermally curable monomer and oligomer precursors could generate suitable, thermally conductive materials for 3D inkjet printing [ 23 , 24 , 25 ].…”