Particle Monolayer Formation with Arrayed Structure by PMMA-<I>Grafted</I> Polystyrene Latex at the Air–Water Interface

Abstract

The structure of the particle monolayer formed by the polymer-grafted latex particle at the air-water interface was estimated mainly by pi--A isotherm measurement and SEM observation to examine the effect of core particle characteristics and to generalize the key factors in determining the polymer-grafted particle monolayer structure. Methyl methacrylate (MMA) was polymerized from the polystyrene latex (PSL) surface by atom transfer radical polymerization to give a PMMA-grafted PSL (PSL-PMMA) with a relatively high graft density of about 0.2 nm-2. We obtained PSL-PMMA with PMMA of different molecular weights but almost the same graft density. The onset area of increasing surface pressure in pi-A isotherm was in agreement with the value of effective radius of PSL-PMMA with quite extended PMMA chains. The particle monolayer structure deposited on the substrate was strongly dependent on the molecular weight of the grafted PMMA. The aggregation size was reduced with increasing molecular weight and a lattice-like structure was observed for PSL-PMMA monolayer with a high molecular weight PMMA. The interparticle distance was decreased and structure becomes ordered with increasing surface pressure. The monolayer structure obtained here was consistent with that of the PMMA-grafted silica particle system. We also synthesized polystyrene (PS)-grafted PMMA latex (PML-PS) and compared the two systems. We confirmed that the lattice-like structure depended on the nature of the grafted PMMA chain, not the core particle characteristics.

Tuning Polymer-Grafted Particle Monolayer Structure at the Air-Water Interface by Introducing Anisotropic Features

“…We do know that the molecular weight used here is relative value and contains errors, however, the agreement of these values supports the extended fairly conformation of PtBMA on a watersurface similar to PMMA system [16].…”

“…former our papers, this indicates that polymer chains grafted from particles are much extended on the water surface [15] [16]. In this data, the occupied area at 1 mN/m is corresponds to the interparticle distance of 388 nm assuming closest packing of particle at the air-water interface.…”

“…On the other hand, two π-A isotherms at different conditions match after plateau region. Based our previous data, below the plateau region the interaction between polymer chains grafted from particle is observed while the interaction between hard spheres is observed above the plateau region [16]. Considering the interpretation of π-A isotherm, it is reasonable We also estimate the surface property of deposited particle monolayer on substrate.…”

“…Polystyrene latex with chloromethyl groups was synthesized by soap-free emulsion polymerization as previously described [16]. The averaged diameter of polystyrene latex was estimated by dynamic light scattering with DLS-8000 (Otsuka Electronics Co., Ltd., Hirakata, Japan).…”

“…We observed the deposited particle layers by SEM (SM-7000FSK, JEOL Ltd., Tokyo, Japan). In order to estimate the basic property of a deposited layer on a substrate, contact angle measurement was measured by dropping 0.5 μL pure water on a substrate and observing the drop shape by a digital camera with a-close-up lens [16]. …”