Effect Of Polymeric Materials Research Articles

Plasma Activation and its Nanoconfinement Effects Boost Surface Anti‐Biofouling Performance

AbstractAlthough plasma treatment can alter polymer surface wettability and adhesiveness, scant attention has been given to plasma effects across scales and their anti‐fouling performance. Herein, the discovery that plasma‐activated polydimethylsiloxane (PDMS) nanopillar arrays remarkably enhance anti‐fouling behavior, yielding a 98.7% reduction in Escherichia coli adhesion compared to native planar surfaces. The plasma‐activated nanopillar arrays can hold to their anti‐fouling properties for extended periods of storage, still exhibiting more than 65.1% less bacterial colonization than their native planar counterparts after 50 days. The anti‐fouling behavior promoted by plasma activation is significantly enhanced as the structure features reduce in size from macroscale to microscale to nanoscale, revealing an altered plasma activation effect upon confinement at the nanoscale level. It is anticipated that the findings will improve the ability to achieve non‐fouling effects in polymeric materials for a broad range of applications in clinical and industrial settings.

Development of a simple setup for temperature dependent mass spectrometric measurements for the investigation of outgassing effects in polymeric materials for solar application

A simple experimental setup for temperature dependent mass spectrometric measurements has been constructed. It consists of a heated sample chamber and a mass spectrometer and allows for measurements under inert gas and ambient air. Based on initial measurements on two extruded polystyrene (XPS) samples a methodology for the data analysis has been developed. With this methodology the outgassing temperature of volatile compounds, which were used as blowing agents, has been identified. Furthermore, the composition of the blowing agents has been analyzed by temperature dependent mass spectra. The results indicate the use of ambient air in one material and a mixture of the banned blowing agents R142b and R22, both hydrochlorofluorocarbons (HCFC), in the other material. The here described methodology provides an easy to use approach to identify such compounds, for example as part of environmental or quality control.

Selectively Deuterated Poly(ε-caprolactone)s: Synthesis and Isotope Effects on the Crystal Structures and Properties

Selective deuteration is an important tool for many analytical techniques including neutron scattering and spectroscopies. However, the availability of deuterated materials is limited because of the challenges in their synthesis. Here, we report the synthesis of partially and fully deuterated ε-caprolactone monomers and their corresponding polymers, poly(ε-caprolactone)s (PCLs), and the investigation of isotope effects on their crystalline structures and physical properties. Deuteration of PCLs leads to smaller crystal lattices and volumes compared to protiated PCLs by the amount proportional to the deuteration levels. The linear trend suggests that the volume isotope effect in PCL is primarily governed by the vibrations of C–D and C–H bonds. The large intrachain contraction of deuterated PCLs compared to that of polyethylene reported in the literature can be ascribed to the presence of polar ester groups in PCLs. Deuterated PCLs also display lower melting temperatures than protiated PCLs proportional to their deuteration levels because of weaker intermolecular interactions in deuterated polymers. FTIR spectroscopy, with support from density functional theory calculations, shows large red shifts of the stretching and bending frequencies of C–D versus C–H bonds as dictated by their relative reduced masses 13/7, and to a smaller degree for the C═O stretching frequency. This work is among the very few studies comparing the effects of partial versus full deuteration on the structures and properties in semicrystalline polymers. These results not only advance our understanding of isotope effects in polymeric materials but also provide an important avenue to design polymers with desirable properties.

Proximate analysis of different groups of irradiated alginic acid

Background: Seaweeds contain significant quan��es of lipids, protein, vitamins and minerals. Aquavac Ergosan contains 1% alginic acid extracted from two brown seaweeds, Laminaria digitata and Ascophyllum nodosum. Both in vivo and in-vitro researches have mainly been focused on the effect of Ergosan on fish growth, survival rate, reproducve performance and innate immunity in blood and epidermal mucus. Despite numerous studies on the ef fects of Ergosan on immune system of aquac animals and evaluaon of seaweeds in proximate analysis, there is no data available on proximate analysis of irradiated Ergosan extract (alginic acid). Therefore, the aim of this study was to assess the effect of on different groups of irradiated alginic acid (10, 20, 30, 40 and 50 KGy) for analyzing proximate composion. Materials and Methods: Alginic acid was prepared from the sonicated Ergosan extract. The Alginic acid extracted from Ergosan was irradiated with a gamma cell. The protein and lipid content and Moisture and ash were recorded. Results: Stascal analysis showed no signif icant dif ferences among all of groups in terms of protein, lipid, ash and moisture. Conclusion: Radiaon processing is a very convenient tool for imparng desirable effects in polymeric materials. The polysaccharide degradaon by gamma or ultraviolet irradiaon is free of iniators. High energy radiaon technique can be effecvely used to decrease the molecular weight of different polysaccharides such as alginate and Chitosan. Based on the results of this study, gamma irradiaon of alginic acid as natural polysaccharide had no effect on crude protein, crude lipid, moisture and ash.

Shape Memory Effect in Polymeric Materials: Mechanisms and Optimization

The shape memory effect (SME) has attracted more and more attention in recent years. A few shape memory related new phenomena have also been identified. This paper aims to reveal the basic working mechanisms for the SME in polymeric materials, and discuss the key issues in optimization of the shape memory performance, temperature memory effect and multiple-SME. It is concluded that most shape memory phenomena are intrinsic features of polymeric materials, and based on these basic working mechanisms, we can enable the SME in materials, design a new shape memory material with the required shape memory function, and optimize the shape memory performance.

Molecular Engineering of Azobenzene-Functionalized Polyimides To Enhance Both Photomechanical Work and Motion

Photomechanical effects in polymeric materials directly convert input photonic energy into a macroscopic mechanical output. The photoinitiated mechanical output of these materials is typically dominated by classical mechanics, primarily derived from the material stiffness and sample geometry. Accordingly, large magnitude shape change (e.g., motion) is typically traded for large magnitude force generation. Here, we report on the systematic preparation and comparison of photomechanical effects in a set of isomerically varied linear and cross-linked azobenzene-functionalized materials that demonstrate the critical role of segmental mobility (evident in the magnitude of the β-transition) to assimilate the typically exclusive properties of large force generation and large shape change in a single material.

Hysteresis in electroactive polymers

Abstract In this paper we present a model for the description of rate-independent hysteresis in Electroactive Polymers (EAPs). Our analysis is based on a model proposed by the authors for the description of damage and healing effects in polymeric materials and on a variational formulation for the resulting electromechanical equilibrium problem. The analysis of the class of equibiaxial strain, relevant for many actuation and energy harvesting devices, evidences that the model is effective and computationally efficient. The model shows a significant agreement with important experimental phenomena observed in EAP devices.

Chemo-responsive Shape Memory/change Effect in Polymeric Materials Based on Transport Phenomena

In this paper, the major fundamental mechanisms based on three transport phenomena, namely, limited swelling, significant swelling and diffusion, for the chemo-responsive shape memory/change effect in polymeric materials are discussed in details. Some recently proposed typical applications of these effects either individually or combined together are presented. It is concluded that various transport phenomena provide us alternative approaches to realize novel devices/structures, which are not easy to be achieved by conventional techniques.

Mechanisms of the Shape Memory Effect in Polymeric Materials

This review paper summarizes the recent research progress in the underlying mechanisms behind the shape memory effect (SME) and some newly discovered shape memory phenomena in polymeric materials. It is revealed that most polymeric materials, if not all, intrinsically have the thermo/chemo-responsive SME. It is demonstrated that a good understanding of the fundamentals behind various types of shape memory phenomena in polymeric materials is not only useful in design/synthesis of new polymeric shape memory materials (SMMs) with tailored performance, but also helpful in optimization of the existing ones, and thus remarkably widens the application field of polymeric SMMs.

Photochemical Mechanism and Photothermal Considerations in the Mechanical Response of Monodomain, Azobenzene-Functionalized Liquid Crystal Polymer Networks

The potential for wireless transduction of input light energy into mechanical outputs has led to a reinvigorated pursuit of photomechanical effects in polymeric materials and composites. We report here on factors influencing the photochemical mechanism (and thus the mechanical output) in monodomain azobenzene-functionalized liquid crystal polymer networks. Through systematic examination of a representative material with both mechanics and spectroscopic characterization the prevalence of the trans–cis and trans–cis–trans mechanisms is elucidated. Furthermore, the role of light intensity in generating heat (photothermal effects) is also reported.

Quantification of the evolution of shape storage and recovery in thermally responsive shape memory polymers

AbstractThis study demonstrates the relevance of strain and stress storage/recovery profiles for the thermomechanical behaviour of thermally responsive Shape Memory Polymers (SMPs). It is shown how these experimentally determined profiles may be used for the development, calibration and validation of continuum‐based models describing the shape memory effect in polymeric materials. The presented methodology applies both to small and finite strain deformation problems under the assumption of constant strain and cooling/heating rates. (© 2010 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Optical Circular-Polarization Modulator Employing Tilt-Poled Electrooptic Polymers

A polymer-based integrated circular-polarization modulator (CPM) is demonstrated in this paper. Tilted poling is adopted to achieve polarization conversion in the electrooptic (EO) polymeric waveguide and then realize the power balance between transverse electric and transverse magnetic modes. Detailed analysis and experiments on polarization conversion are presented. The tensor nature of poled polymeric materials is used to generate the phase difference. Contact poling is applied to perform tilted poling and activate the EO effect of polymeric materials. With appropriate voltage control, the polarization state of the output from the CPM can alternate between the left and right-hand-circular states. The extinction ratios at the 45/spl deg/- and -45/spl deg/-tilted linearly polarized states are larger than 25 dB.

Radiation-Induced Modifications in Polymeric Materials

ABSTRACTRadiation-induced modifications in polymeric materials are briefly reviewed. The attention is paid to the effect of ionizing radiation on the mechanical properties of polymers. The competition between several parallel degradation processes in the harsh conditions of the space environment is analyzed. The need for a complex analysis of the effect of polymeric materials in simulated space environments is demonstrated.

Application of the nonlinear theory of heredity to the description of time effects in polymeric materials

A relation is established between the heredity theory with time-invariant nonlinearity and fractional-exponential kernels and the Volterra-Frechet theory for uniaxial tension. A constitutive equation is proposed for processes accompanied by decreasing strain. A procedure for determining the necessary material characteristics from creep and recovery data is considered.