Synthesis and Study of the Optical Properties of PMMA Microspheres and Opals

Abstract

Polymethylmethacrylate (PMMA) microspheres were synthesized by surfactant-free emulsion polymerization. These microspheres were used to obtain opals by the self-assembly method. Monomer and initiator quantities were varied systematically to monitor the size of PMMA microspheres. From SEM and DLS measurements, a trend was observed showing as the monomer and initiator amounts increased the average diameter of PMMA microspheres increased except when a minimum monomer amount was reached, for which the size of the microspheres remained practically constant. Diffuse reflectance spectra were processed by the Kubelka–Munk treatment to estimate the energy band gap (Eg) of the PMMA microspheres. It was found that PMMA microspheres present an indirect transition. From SEM micrographs, it is seen that PMMA opals photonic crystals are formed by microspheres in a uniform periodic face-centered cubic (fcc) array. Variable-angle specular reflectance spectra show that the opals possess a pseudo photonic band gap (PBG) in the visible and near-IR regions. Furthermore, it was found that PBGs shift towards larger wavelengths as the average diameter of the PMMA microspheres increases.

Unrevealing the opto-structural features of luminescent polymeric films containing EuIII-doped phosphors through spectroscopic and theoretical perspectives

“…The band at 250 nm in the DR spectra is assigned to the Eu III → O 2− charge transfer band (CTB), 32 while the band within the 250–400 nm range is assigned to the phosphor band gap, which overlaps with the PMMA absorption bands above 300 nm. 60 However, prior to deposition, the particles were discreetly agglomerated leading to an uneven size distribution, which in turn can result in significant light scattering of UV radiation. This scattering can overlap with the CTB, affecting the profile of the DR spectra.…”

Space-resolved chemical information from infrared extinction spectra

“…While these examples are important for testing validity and robustness of the Lorentzian method, IR spectroscopy on homogeneous and layered spheres may also have practical importance, for instance in mineralogy, or for characterizing micro-and nano-spheres, such as PMMA or PS spheres. PMMA spheres, in particular, are frequently used as model systems for biological cells 11,12,[18][19][20][21] .…”

Space-Resolved Chemical Information from Infrared Extinction Spectra

“…While these examples are important for testing validity and robustness of our method, IR spectroscopy on homogeneous and layered spheres may also have practical importance, for instance in 3/11 mineralogy, or for characterizing micro-and nano-spheres, such as PMMA or PS spheres. PMMA spheres, in particular, are frequently used as model systems for biological cells 11,12,21,[23][24][25] .…”