Epoxy resin reinforced with nanothin polydopamine-coated carbon nanotubes: a study of the interfacial polymer layer thickness

Carbon nanotubes (CNTs) functionalized by a nanothin poly(dopamine) (PDA) layer were produced by a one-pot, nondestructive approach, with direct polymerization of dopamine on the CNT surface.

A new route of emulsifier-free emulsion polymerization for the preparation of polymer coated magnetite nanoparticles

A new route of emulsifier-free emulsion polymerization based on the homogenous mechanism was investigated to prepare magnetic nanoparticles coated by poly (methyl methacrylate) (PMMA). The experimental results confirm the formation of PMMA thin and unique layers covering magnetite cores. The polymer layer thickness, determined from transmission electron microscopy (TEM) images, increases from 4.3 nm to 6.8 nm with increasing mass ratio of MMA to magnetite from 3:1 to 11:1. The increase of the polymer thickness results in the decrease in magnetization saturation of polymeric coated magnetic particles. However, this reduction, no more than 13 emu g−1, is much lower compared to that in other studies with the presence of surfactants or emulsifiers. Besides, the dispersion stability of the prepared particles is significantly improved.

A Rapid Evaluation Method to Assess Organic Film Uniformity in Roll-to-Roll Manufactured OLEDs.

In order to enable low cost roll-to-roll or sheet-processing of organic light-emitting diode (OLED) devices, completely new deposition methods for both polymer and smallmolecule layers are being developed in place of the classic semiconductor manufacturing methods. In evaluating the utility of such methods, it is advantageous to have a robust and fast method to measure the thickness uniformity of the deposited organic layers. Non-uniformities at all spatial length scales from sub-mm to several cm can occur and so need to be understood as a function of the relevant parameters for each deposition method. Here we demonstrate a simple and fast method to quantify non-uniformities in thin films over arbitrarily large length scales. Our method utilizes the color of light reflected from the coated substrate and its variation with polymer layer thickness. This concept of color change is well known, and is due to constructive interference of light of particular wavelengths related to polymer layer thickness and optical constants. In our modification, a digital camera is used to capture images of the coated substrates, and hue is extracted from the image data files. We show that hue can be linearly correlated with polymer thickness. We demonstrate this for polymer based OLEDs using poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate) (PEDOT:PSS) and a light-emitting polymer (LEP) deposited on transparent substrate. The correlations were successfully used for 40-140nm PEDOT:PSS layers and 20-110nm LEP layers over length scales greater than 1 inch. The method sensitivity is estimated to be better than 5 nm. We show examples of non-uniformity analysis and how it relates to OLED performance.