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Polymers

Ubiquitous use of polymers in technology and in our daily lives is due to their excellent chemical and physical properties, processability and relatively low cost. The vast application of polymers is only possible through development and understanding of polymer properties and behavior. Whether polymer nanostructures or polymer nanocomposites (PNC), with Anton Paar’s portfolio of measuring technologies, a variety of research investigations can be performed. Read below about investigation of polymers with atomic force microscopy, and thermo-optical oscillating refraction characterization for nanoparticle influence on reaction and physical polymer properties.

Complete atomic force microscopy investigation of a polymer thin film

Introduction

For complete characterization of a polymer thin film, often mechanical, electric and also chemical properties are needed. Performing investigations of different physical properties on the same sample location is problematic with AFM, as hardware changes between different modes are required. With the example of a thin-film polymer blend, we introduce a novel possibility for AFM investigation of different physical properties on the same sample location without any hardware change. This approach also enables the superposition of different properties for better and more precise understanding of surface characteristics.

Experimental

An AFM investigation of a PMMA/SBS polymer blend (2:1 ratio) was performed on a 25 μm x 25 μm area with a resolution of 400 pixels x 400 pixels and a scan rate of 0.5 line/seconds. Force distance curve, contact resonance amplitude imaging (CRAI), electrostatic force microscopy (EFM) and Kelvin probe force microscopy (KPFM) were employed at the same position with a single hardware set-up and the same cantilever, without any hardware changes in between the measurements.

Results and discussion

First, mechanical properties of the sample were investigated by means of the Contact Resonance Amplitude Imaging (CRAI) mode for precise differences in mechanical properties of different domains, followed by force distance curve investigation, to quantitatively determine the Young’s modulus of two distinct domains. For the electrical sample properties, the Kelvin probe Force microscopy investigation of the same location on the sample surface was then performed without any change in the hardware set-up. To answer the question of the precise polymer distribution and the composition of islands (structures), we established superposition of 3D CRAI and KPFM measurements, which is only possible if the 2 measurements are performed at exactly the same position, as shown in Fig. 1.

Fig. 1. Superposition of 3D CRAI amplitude and contact potential difference (CPD)

Nanoparticle influence on reaction and physical properties of the polymerized sample matrix

Introduction

The polymerization reaction and material properties of polymers can be strongly influenced by adding pigments, co-polymers and fillers. Nanomaterials can be used as they exhibit greater deviating influences on polymer properties than their macro counterparts. Glass transition of amorphous regions interacts with semi-crystallin polymer sections. This can, e.g., form components with high temperature resistance, but also better ductility properties. Investigating the influence on the polymerization properties, e.g. reaction speed or chemically induced glass transition (vitrification), is necessary for research purposes. The TORC allows live reaction monitoring with analysis of reaction speed, and kinetic and sample changes by refractive index.

Experimental

Polymerization example: Resin diglycidylether of bisphenol A (DGEBA) and of the hardener diethylene triamine (DETA) with a mass ratio of 100 g:20 g +1% addition of nano-sphere PMMA.

The comparison can either be performed without PMMA additive or with macroscopic PMMA of an average molecular weight of 120.000 GPC.

Characterization techniques and parameters: TORC 5000. Add the sample with a size of 100 µL premixed. Set standard polymerization conditions for polymerization of e.g. 100 °C and TORC specific parameters of 30 s period and 0.5 °C amplitude.

Results and discussion

The TORC technique allows an inside view into reaction speed, temperature influence and reaction kinetics.

The influence of the nanoparticles on these processes can be observed by comparing the TORC results with reference results from mixed samples without nanoparticle additives. This interference can, e.g., result in lower sensitivity to temperature conditions. The origin temperature dependent on the reaction speed and vitrification process for DGEBA + DTEA at a ratio of 100 g:20 g and with a PMMA polymer filler – or even without filler – was two times more temperature-dependent than the reaction with nano-sphere PMMA particles. The reaction temperature dependence observed is close to the Arrhenius rule behavior of doubled reaction speed by 10K temperature improvement. In this instance, the materials didn’t only improve their properties, they could even be applied across wider environmental conditions.

Additional information

Instruments:

Source:

Application report:

  • Characterizing the curing reaction