Name: Placing Polystyrene (PS) Beads onto the PVA-Coated Surface
Uploaded: 2023-06-23T14:55:00
Description: Watch this Scientific Journal Video about Placing Polystyrene PS Beads onto the PVA-Coated Surface at JoVE.com

placing polystyrene (ps) beads onto the pva-coated surface

Exploration des systèmes polymères multiphasiques par spectroscopie infrarouge à l’échelle nanométrique

Atomic force microscopy (AFM) has become essential to image and characterize the morphology of a wide variety of samples with nanoscale resolution1,2,3. By measuring the deflection of an AFM cantilever resulting from the interaction of the sharp tip with the sample surface, nanoscale functional imaging protocols for local stiffness measurements and tip-sample adhesion have been developed4,5. For soft condensed matter and polymer analysis, AFM measurements exploring the nanomechanical and nanochemical properties of local domains are highly sought after6,7,8. Before the emergence of nanoscale infrared (nanoIR) spectroscopy, AFM tips were chemically modified to assess the presence of different domains from the AFM force curve and deduct the nature of the tip-sample interaction. For instance, this approach was used to unveil the transformation of microdomains of poly(tert-butyl acrylate) at the surface of cyclohexane-treated polystyrene-block-poly(tert-butyl acrylate)block copolymer thin films at the sub 50 nm level9.
The combination of infrared (IR) light with AFM has had a significant impact on the field of polymer science6. Conventional IR spectroscopy is a widely used technique for studying the chemical structure of polymeric materials10,11, but it fails to provide information on individual phases and interphase behavior, as the regions are too small compared to the size of the IR beam used to probe the sample. The problem holds with IR microspectroscopy, as it is restricted by the optical diffraction limit6. Such measurements average the contributions of the entire region excited by the IR light; the signals resulting from the presence of nanoscale phases inside the probed region either exhibit complex fingerprints that should be deconvoluted during post-processing or are lost due to a signal level below the detectable level. Hence, it is essential to develop tools capable of nanoscale spatial resolution and high IR sensitivity to explore nanoscale chemical features in complex media.
Schemes to achieve nanoIR spectroscopy have been developed, first using a metallic AFM tip as a nanoantenna12,13, and more recently exploiting the AFM cantilever&#39;s ability to monitor changes in the photothermal expansion incurred during IR illumination of the sample12,14,15. The latter uses a pulsed, tunable IR light source tuned to an absorption band of the material probed, which causes the sample to absorb radiation and undergo photothermal expansion. This approach is well-suited for organic and polymeric materials. The pulsed excitation makes the effect detectable by the AFM cantilever in contact with the sample surface in the form of an oscillation. The amplitude of one of the contact resonances of the system observed in the frequency spectrum is then monitored as a function of illumination wavelength, which constitutes the nanoIR absorption spectrum of the material beneath the AFM tip15. The spatial resolution of nanoIR imaging and spectroscopy is limited by various effects of the photothermal expansion of the material. It has been evaluated that photothermal nanoIR spectroscopy using contact mode AFM can acquire the vibrational absorption spectra properties of materials with sub 50 nm scale spatial resolution14, with recent work demonstrating the detection of monomers and dimers of &#945;-synuclein16,17. However, quantitative studies of the performance of nanoIR measurements on heterogeneous polymeric materials assembled in various configurations, such as the case of absorbers of finite dimensions embedded in the volume of various polymeric films, remain limited.
This article aims to create a polymeric assembly with an embedded feature of a known dimension to evaluate the sensitivity of photothermal expansion and spatial resolution of nanoIR during surface analysis. The protocol covers the preparation of a polyvinyl alcohol (PVA) polymer thin film on a silicon substrate and the placement of a three-dimensional polystyrene (PS) bead onto or embedded in the PVA film, which constitutes the formation of the model system. NanoIR imaging and spectroscopy measurements are described in the context of evaluating the signals generated by the same PS bead positioned on or beneath the PVA film. The influence of the bead position on the nanoIR signals is evaluated. Methods to assess the spatial footprint of the bead in the nanoIR map are discussed, and the effects of several parameters are considered.

Pleins feux sur l’auteur : Progrès de la spectroscopie infrarouge à l’échelle nanométrique pour explorer les systèmes polymères multiphasiques  

Avancées dans la spectroscopie infrarouge à l’échelle nanométrique pour explorer les systèmes polymériques multiphasiques

Our group focuses on advancing the field of nanoscale functional imaging and spectroscopy to study complex systems with an emphasis on nanoscale infrared spectroscopy. Our research aims to develop methods that allows us to make sense of the behavior of heterogeneous systems by studying their nanoscale properties. Understanding the role of actuations at different frequencies to extract information about the sample is essential.As this is complicated, developing samples that can be modeled with physics simulation packages is also important. A nanoscale infrared spectroscopy determining the penetration depth of the measurement and understanding how subsurface features affect the signal detected by the AFM tip is very important. This protocol proposes a simple approach to create a model system that enables quantifying the penetration depth of nanoscale infrared spectroscopy, and the effect of JUUL heating on the sample response involved in the measurement of multi-phase polymer materials.Our team will continue to focus on developing new ideas to improve nanoscale infrared spectroscopy and other nanoscale functional tools to explore real-life systems at a small scale.

Watch this Scientific Journal Video about Placing Polystyrene PS Beads onto the PVA-Coated Surface at JoVE.com

Placing Polystyrene (PS) Beads onto the PVA-Coated Surface  

Placer des billes de polystyrène (PS) sur la surface revêtue de PVA

Pour commencer, nettoyez un substrat de silicone à l’aide d’alcool isopropylique et laissez-le sécher à l’air libre. À l’aide d’une pipette, placez un microlitre de billes de polystyrène en suspension dans l’eau au centre du substrat. Placez le substrat ajouté aux billes de polystyrène dans un compartiment de stockage contenant un dessiccant d’argile bentonite pour permettre à l’eau de s’évaporer.Examinez le substrat de billes de polystyrène séchées et un substrat recouvert d’alcool polyvinylique ou de PVA préalablement préparé au microscope optique. À l’aide d’une pince à épiler ultra fine, perdez doucement les perles, puis collectez quelques perles à l’aide d’un pinceau à poils fins et tapotez doucement les poils du pinceau sur la plaquette fraîchement enduite de PVA. Répétez la collecte des billes jusqu’à ce que les billes de polystyrène individuelles adhèrent à la surface PVA, comme confirmé par microscopie optique.Le dépôt des billes de polystyrène a été confirmé par l’imagerie par microscopie électronique à balayage de la bille de cinq micromètres au-dessus d’un substrat de silicium vierge au-dessus d’un film PVA et recouverte de PVA.

Research

JoVE Journal

Engineering

Placing Polystyrene (PS) Beads onto the PVA-Coated Surface

Advances in Nanoscale Infrared Spectroscopy to Explore Multiphase Polymeric Systems

Multiphase polymeric systems encompass local domains with dimensions that can vary from a few tens of nanometers to several micrometers. Their composition ...