Temperature can be harnessed to engineer unique properties for materials useful in various contexts and has been shown to affect the layer-by-layer (LbL) assembly of polymer thin films and cause physical changes in preassembled polymer thin films. Herein we demonstrate that exposure to relatively low temperatures (≤ 100 °C) can induce physicochemical changes in cationic polymer thin films. The surface charge of polymer films containing primary and secondary amines reverses after heating (from positive to negative), and different characterization techniques are used to show that the change in surface charge is related to oxidation of the polymer that specifically occurs in the thin film state. This charge reversal allows for single-polymer LbL assembly to be performed with poly(allylamine) hydrochloride (PAH) through alternating heat/deposition steps. Furthermore, the negative charge induced by heating reduces the fouling and cell-association of PAH-coated planar and particulate substrates, respectively. This study highlights a unique property of thin films which is relevant to LbL assembly and biofouling and is of interest for the future development of thin polymer films for biomedical systems.
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http://dx.doi.org/10.1021/acsami.6b00472 | DOI Listing |
Polymers (Basel)
January 2025
Department of Physics, Washington State University, Pullman, WA 99163, USA.
This work aims to determine the mechanism of the photomechanical response of poly(Methyl methacrylate) polymer doped with the photo-isomerizable dye Disperse Red 1 using the non-isomerizable dye Disperse Orange 11 as a control to isolate photoisomerization. Samples are free-standing thin films with thickness that is small compared with the optical skin depth to assure uniform illumination and photomechanical response throughout their volume, which differentiates these studies from most others. Polarization-dependent measurements of the photomechanical stress response are used to deconvolute the contributions of angular hole burning, molecular reorientation and photothermal heating.
View Article and Find Full Text PDFSensors (Basel)
January 2025
Institute of Nanotechnologies, Electronics and Equipment Engineering, Southern Federal University, 347922 Taganrog, Russia.
One of the challenging problems in the research and development of vibration sensors relates to the formation of Ohmic contacts for the removal of an electrical signal. In some cases, it is proposed to use arrays of carbon nanotubes (CNTs), which can serve as highly elastic electrode materials for vibration sensors. The purpose of this work is to study the effect of a current-collecting layer of CNTs grown over silicon on the properties of a lead zirconate titanate (PZT) film, which is frequently employed in mechanical vibration sensors or energy harvesters.
View Article and Find Full Text PDFMolecules
January 2025
Information Materials and Intelligent Sensing Laboratory of Anhui Province, Anhui University, Hefei 230601, China.
Carbon-based nanomaterials with excellent electrical and optical properties are highly sought after for a plethora of hybrid applications, ranging from advanced sustainable energy storage devices to opto-electronic components. In this contribution, we examine in detail the dependence of electrical conductivity and the ultrafast optical nonlinearity of graphene oxide (GO) films on their degrees of reduction, as well as the link between the two properties. The GO films were first synthesized through the vacuum filtration method and then reduced partially and controllably by way of femtosecond laser direct writing with varying power doses.
View Article and Find Full Text PDFMaterials (Basel)
January 2025
Department of Biomaterials and Cosmetic Chemistry, Faculty of Chemistry, Nicolaus Copernicus University in Torun, 7 Gagarin Street, 87-100 Torun, Poland.
Biopolymers represent a significant class of materials with potential applications in skin care due to their beneficial properties. Resveratrol is a natural substance that exhibits a range of biological activities, including the scavenging of free radicals and anti-inflammatory and anti-aging effects. In this study, chitosan/konjac glucomannan resveratrol-enriched thin films were prepared.
View Article and Find Full Text PDFMaterials (Basel)
January 2025
College of Civil Engineering, Nanjing Forestry University, Nanjing 210037, China.
The global asphalt production growth rate exceeded 10% in the past decade, and over 90% of the world's road surfaces are generated from asphalt materials. Therefore, the issue of asphalt aging has been widely researched. In this study, the aging of asphalt thin films under various natural conditions was studied to prevent the distortion of indoor simulated aging and to prevent the extraction of asphalt samples from road surfaces from impacting the aged asphalt.
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