Lattice Dynamics of Colloidal Crystals During Photopolymerization of Acrylic Monomer Matrix

• Published in: Journal of materials science Vol. 33; no. 4; pp. 887 - 894
• Main Authors: Sunkara, H. B, Penn, B. G., Frazier, D. O., Ramachandran, N.
• Format: Journal Article
• Language: English
• Published: Marshall Space Flight Center Chapman and Hall 15.02.1998; Springer; Springer Nature B.V
• Subjects: Applied sciences; Arrays; Bulk polymerization; Crystal lattices; Dielectric properties; Diffraction; Exact sciences and technology; Fluid filters; Materials science; Monomers; Optical filters; Orientation effects; Photopolymerization; Physicochemistry of polymers; Polymerization; Polymers and radiations; Shrinkage; Silicon dioxide; Solid-State Physics; Composite film; Methyl methacrylate polymer; Experimental study; Property processing relationship; Silica; Methyl acrylate polymer; Latex; Colloidal gel; Heterogeneous polymerization; Optical filter; Photopolymerization; Optical properties; Preparation; Acrylamide polymer; Optical material; Styrene polymer; Colloid particle
• ISSN: 0022-2461; 1573-4803
• DOI: 10.1023/A:1004391207264

The photoinitiated bulk polymerization process, which has been used recently in the manufacture of solid optical diffraction filters, is examined to understand the dynamics of both the crystalline colloidal arrays (CCA) and the host monomer species. Our analysis indicates that volume shrinkage of the monomer, changes in the dielectric properties of the monomer, and inhomogeneities of polymerization reaction rate across the dispersion during the polymerization process, are the major contributors for observed lattice compression and lattice disorder of the CCA of silica spheres in polymerized acrylic/methacrylic ester films. The effect of orientation of photocell with respect to the radiation source on Bragg diffraction of CCA indicated the presence of convective stirring in the thin fluid system during the photopolymerization that deleteriously affects the periodic array structures. To devise reproducible and more efficient optical filters, experimental methods to minimize or eliminate convective instabilities in monomeric dispersions during polymerization are suggested.