Multifunctionality of polypyrrole polyethyleneoxide composites: Concurrent sensing, actuation and energy storage

In films of conducting polymers, the electrochemical reaction(s) drive the simultaneous variation of different material properties (reaction multifunctionality). Here, we present a parallel study of actuation-sensing-energy storage triple functionality of polypyrrole (PPy) blends with dodecylbenzenesulfonate (DBS-), PPy/DBS, without and with inclusion of polyethyleneoxide, PPy-PEO/DBS. The characterization of the response of both materials in aqueous solutions of four different salts indicated that all of the actuating, sensing and charge storage responses were, independent of the electrolyte, present for both materials, but stronger for the PPy-PEO/DBS films: 1.4× higher strains, 1.3× higher specific charge densities, 2.5× higher specific capacitances and increased ion-sensitivity towards the studied counterions. For both materials, the reaction energy, the material potential and the strain variations adapt to and sense the electrical and chemical (exchanged cation) conditions. The driving and the response of actuation, sensing and charge can be controlled/read, simultaneously, via just two connecting wires. Only the cooperative actuation of chemical macromolecular motors from functional cells has such chemical multifunctionality. © 2020 by the authors

Mining of mineral resources and its impact on the surrounding environment in Pärnu county

Bakalaureuse töös on toodud ülevaade Pärnu maakonnas kaevandatavatest maavaradest kehtivate kaevelubade alusel 2014 aasta seisuga. Töö eesmärgiks on selgitada erinevaid võimalusi ammendatud karjääride taasloodustamiseks ning juhtida tähelepanu kohalike omavalitsuste ja kaevandajate koostöö vajalikkusele karjäärialade edasise majandustegevuse planeerimisel. Pärnu maakonna tähtsamaks maavaraks on turvas. 2013 a. oli maakonnas 32 turbamaardlat (millest kaevandati kuues), 18 kruusa- ja 22 ehitusliiva maardlat. Üleriigilise tähtsusega on Anelemma dolomiidi karjäär ja Arumetsa savimaardla. Maakonnas leidub veel järvemuda, mis on sobilik raviotstarbeliseks ja väetisena kasutuseks, ning meremuda ja järvelupja, kuid neid ei kaevandatud. Ammendunud turbakaevandusaladel on päideroo kasvatamine jääksoos andnud häid tulemusi. See seostub ka Eesti energiamajanduskavaga aastani 2020, mille alusel peab kombijaamades toodetud elektrienergia osakaal moodustama aastaks 2020 kogutarbimisest 20%. Jääksoode ja ammendunud karjääride metsastamisel saab mulla viljakuse parandamiseks kasutada väetise asemel puu- ja briketituhka, tsemenditolmu ning reovee setteid. Rekultiveeritud karjäärialasid on võimalik kasutada turismi- ja elamuehituse arendamiseks, samuti sobivad nad ka jahipidamiseks ja sõjaväe harjutusaladeks.The aim of the bachelors thesis is to provide an overview of different excavated mineral resources in Pärnu county (in 2014). The purpose is to explain different ways how exhausted quarries can be naturally restored, how they can be used again, to point out the importance of cooperation between local authorities and quarries in further economical planning and the need for effective governmental control. The most important natural mineral resource in Pärnu county is peat. In 2013 there were 32 peat deposits (of which 6 were excavated), 18 gravel quarries and 22 construction sand quarries operating. Analema dolomite quarry and Arumetsa clay mineral deposit are of national importance. Lake mud (which is used in therapeutic purposes as well as a feritiliser), sea mud and lime from lakes are also found in Pärnu county, but they were not excavated. The results of cultivating reed canary grass on the exhausted peat quarries have been good. This is in line with Estonian energy economics plan until 2020, which states that electricity produced from combined station will have to be 20% of the total energy consumption by the year 2020. Instead of using fertilisers, ash from wood and briquet made of peat, cement dust and sewage sludge can be used to improve the soil fertility on residual swamps and afforestation of exhausted quarries. Recultivated quarry areas can be used for tourism and housing development, as well as for hunting purposes or for training area for army

Wider Potential Windows of Cellulose Multiwall Carbon Nanotube Fibers Leading to Qualitative Multifunctional Changes in an Organic Electrolyte

The trend across the whole of society is to focus on natural and/or biodegradable materials such as cellulose (Cell) over synthetic polymers. Among other usage scenarios, Cell can be combined with electroactive components such as multiwall carbon nanotubes (CNT) to form composites, such as Cell-CNT fibers, for applications in actuators, sensors, and energy storage devices. In this work, we aim to show that by changing the potential window, qualitative multifunctionality of the composites can be invoked, in both electromechanical response as well as energy storage capability. Cell-CNT fibers were investigated in different potential ranges (0.8 V to −0.3 V, 0.55 V to −0.8 V, 1 V to −0.8 V, and 1.5 V to −0.8 V), revealing the transfer from cation-active to anion-active as the potential window shifted towards more positive potentials. Moreover, increasing the driving frequency also shifts the mode from cation- to anion-active. Scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) spectroscopy were conducted to determine the ion species participating in charge compensation under different conditions

Catching up, forging ahead or falling behind? Central & Eastern European development in 1990-2005

This paper aims to assess the economic development and development policies in the Central and Eastern European (CEE) countries in 1990-2005, from the collapse of the USSR to the enlargement of the European Union. A great number of authors have generally seen the transition as a very positive process. They have concluded that the reform policies focusing on macroeconomic and price stability have been the key to success for CEE economies. A reliable economic environment is, of course, instrumental for longer-term economic success, as exemplified by the prolonged crisis in most of the former Soviet Union. Our analysis of the economic development and competitive advantages in the region, however, leads to the conclusion that the specific approach to transition that the Central and Eastern European countries followed came at a rather high cost. Comparative neglect and weakness of a set of policies crucial for longer-term development, such as science, technology and innovation policies, has led to deterioration in the last decade rather than the strengthening of the competitive advantages of Central and Eastern European economies. Furthermore, we argue that, in most cases, CEE countries have unfortunately overlooked or misjudged a number of development challenges, and have thus implemented policies that have generated growth at the cost of rapidly increasing risks. This is how the financial fragility of several Central and Eastern European countries has recently increased drastically, and the region seems to have virtually arrived at the brink of economic collapse. Since the CEE countries joined the European Union, the CEE governments have gradually moved towards acquiring a more active role in economic development. These policies need, however, to be strengthened considerably and reinforced by macroeconomic policies that curb current excessive dependence on foreign-financed growth.Central and Eastern Europe; industrial dynamics; innovation policy; financial fragility

Cellulose-Multiwall Carbon Nanotube Fiber Actuator Behavior in Aqueous and Organic Electrolyte

As both consumers and producers are shifting from fossil-derived materials to other, more sustainable approaches, there is a growing interest in bio-origin and biodegradable polymers. In search of bio-degradable electro-mechanically active materials, cellulose-multi wall carbon nanotube (Cell-CNT) composites are a focus for the development of actuators and sensors. In the current study, our aim was to fabricate Cell-CNT composite fibers and study their electro-mechanical response as linear actuators in aqueous and propylene carbonate-based electrolyte solutions. While the response was (expectedly) strongly solvent dependent, the different solvents also revealed unexpected phenomena. Cell-CNT fibers in propylene carbonate revealed a strong back-relaxation process at low frequencies, and also a frequency dependent response direction change (change of actuation direction). Cell-CNT fibers operated in aqueous electrolyte showed response typical to electrochemical capacitors including expansion at discharging with controllable actuation dependence on charge density. While the response was similarly stable in both electrolyte solution systems, the aqueous electrolytes were clearly favorable for Cell-CNT with 3.4 times higher conductivities, 4.3 times higher charge densities and 11 times higher strain

692 A Unified Treatment of Solvent Properties

Principal component analysis (PCA) has been carried out with 40 solvent scales as variables, each having 40 data points for 40 solvents as objects. The first three components account for 74 % of the total variance. For 36 of the scales, an average of 88 % of the variance is described by the first three principal components. The solvents and the solvent scales are grouped according to the scores and loadings obtained from PCA treatment. This allows comparison of both solvent scales and characterization of individual solvents

Electrochemomechanical Behavior of Polypyrrole-Coated Nanofiber Scaffolds in Cell Culture Medium

Glucose-gelatin nanofiber scaffolds were made conductive and electroactive by chemical (conductive fiber scaffolds, CFS) and additionally electrochemical polypyrrole deposition (doped with triflouromethanesulfonate CF3SO3−, CFS-PPyTF). Both materials were investigated in their linear actuation properties in cell culture medium (CCM), as they could be potential electro-mechanically activated cell growth substrates. Independent of the deposition conditions, both materials showed relatively stable cation-driven actuation in CCM, based on the flux of mainly Na+ ions from CCM. The surprising result was attributed to re-doping by sulfate anions in CCM, as also indicated by energy-dispersive X-ray (EDX) spectroscopy results. Overall, the electrochemically coated material outperformed the one with just chemical coating in conductivity, charge density and actuation response

Concept of an artificial muscle design on polypyrrole nanofiber scaffolds.

Here we present the synthesis and characterization of two new conducting materials having a high electro-chemo-mechanical activity for possible applications as artificial muscles or soft smart actuators in biomimetic structures. Glucose-gelatin nanofiber scaffolds (CFS) were coated with polypyrrole (PPy) first by chemical polymerization followed by electrochemical polymerization doped with dodecylbenzensulfonate (DBS-) forming CFS-PPy/DBS films, or with trifluoromethanesulfonate (CF3SO3-, TF) giving CFS-PPy/TF films. The composition, electronic and ionic conductivity of the materials were determined using different techniques. The electro-chemo-mechanical characterization of the films was carried out by cyclic voltammetry and square wave potential steps in bis(trifluoromethane)sulfonimide lithium solutions of propylene carbonate (LiTFSI-PC). Linear actuation of the CFS-PPy/DBS material exhibited 20% of strain variation with a stress of 0.14 MPa, rather similar to skeletal muscles. After 1000 cycles, the creeping effect was as low as 0,2% having a good long-term stability showing a strain variation per cycle of -1.8% (after 1000 cycles). Those material properties are excellent for future technological applications as artificial muscles, batteries, smart membranes, and so on

A Kirigami Approach of Patterning Membrane Actuators

Ionic electroactive polymer actuators are typically implemented as bending trilayer laminates. While showing high displacements, such designs are not straightforward to implement for useful applications. To enable practical uses in actuators with ionic electroactive polymers, membrane-type film designs can be considered. The significantly lower displacement of the membrane actuators due to the lack of freedom of motion has been the main limiting factor for their application, resulting in just a few works considering such devices. However, bioinspired patterning designs have been shown to significantly increase the freedom of motion of such membranes. In this work, we apply computer simulations to design cutting patterns for increasing the performance of membrane actuators based on polypyrrole doped with dodecylbenzenesulfonate (PPy/DBS) in trilayer arrangements with a polyvinylidene fluoride membrane as the separator. A dedicated custom-designed device was built to consistently measure the response of the membrane actuators, demonstrating significant and pattern-specific enhancements of the response in terms of displacement, exchanged charge and force