Film formation from surfactant-free, slightly crosslinked, fluorescein-labeled polystyrene particles

Abstract

A steady state-fluorescence (SSF) technique for studying film formation from surfactant-free, slightly crosslinked polystyrene (PS) latex particles is reported. The powder films were prepared from fluorescein (F)-labeled PS particles at room temperature. The mechanically strong films were obtained by annealing these films at elevated temperatures in 5, 10, 20, and 30 min time intervals above the glass transition (T g ) temperature of polystyrene. Scattered light (I s ) and fluorescence (I F ) intensities from F were monitored after each annealing step to investigate the three different film formation stages called void closure, healing, and interdiffusion. The evolution of transparency of the latex films was monitored by using a photon transmission technique. Scanning electron microscopy (SEM) was employed to detect the variation in physical structure of the annealed latex films. Onset temperature for void closure, T m , and healing temperatures, T h , were determined and corresponding activation energies were measured. Void closure and interdiffusion stages were also modeled and the related activation energies were also determined. It was observed that lower energy is needed for the void closure process than interdiffusion of chains across the particle-particle boundaries.

Spectroscopic study of film formation from polystyrene latex/TiO2nanocomposites prepared by dip-coating method

“…On the other hand, the increase in I P above T 0 presumably corresponds to the void closure process up to the T h point where the healing process takes place. Decrease in I P above T h can be understood by interdiffusion processes between polymer chains [45,46]. I P , I sc , and I tr curves of thick and thin PS/TiO 2 composite films for various TiO 2 layer content annealed at various temperatures are also shown in Figs.…”

“…Before annealing, since the film contains many voids (i.e., the high number of polymer–air boundaries) most of the light is scattered at the air–polymer interface (surface scattering). Annealing the films first causes the closure of voids due to the viscous flow of PS polymer and then healing of the particle–particle boundaries . Therefore, I tr increases with annealing temperature as shown in Figs.…”

“…On the other hand, the increase in I P above T 0 presumably corresponds to the void closure process up to the T h point where the healing process takes place. Decrease in I P above T h can be understood by interdiffusion processes between polymer chains .…”

Study of film formation from PS latex/TiO2 nanocomposites; Effect of latex size and TiO2 content

“…PS starts to flow due to annealing, and voids between particles can be filled due to the viscous flow. Further annealing at higher temperature causes healing and interdiffusion processes [37][38][39][40], resulting in a more transparent film.…”

Effect of annealing on the phase structure and the properties of the film formed from P(St-co-BA)/P(MMA-co-BA) composite latex

“…It has been revealed that when annealing a hard latex system above the minimum film formation temperature (MFFT), deformation of particles first leads to void closure and then, after the voids disappear, diffusion across particleparticle boundaries starts. Hence, the quality of the hard latex films depends on the annealing time and annealing temperature [18][19][20][21][22][23][24][25][26]. However, the film formation process of a composite latex is more complicated than homogeneous latex due to the interactions between the different phases.…”