Elektronvezető polimer alapú összetett (kompozit) anyagok előállítása és tulajdonságaik tanulmányozása in situ kombinált elektrokémiai technikákkal = Preparation of electronically conducting polymer based composite materials and their characterization by in situ combined electrochemical techniques

A kutatás témája elektronvezető tulajdonságú polimer alapú összetett anyagok előállítása és tulajdonságaik tanulmányozása in situ kombinált elektrokémiai technikákkal. A kutatási program kiterjedt fémet tartalmazó kompozitanyagokra, elsődlegesen nemesfémek beépítésére, a inhibítorokat tartalmazó polimerrétegek korrózióvédő hatására, nanoszerkezetű összetett anyagok vizsgálatára, nanodiszperz fémekkel és oxidokkal adalékolt polipirrol és politiofén rétegek vezetési sajátságaira, valamint biológiai hatásuk folytán fontos anyagok polimerrétegekbe történő beépítésére és segítségükkel elektro-biotechnológiai folyamatok megvalósítására. Kutatási eredményeinkből eddig 8 folyóiratcikk jelent meg, melyek összesített hatástényezője mintegy 20. Munkánkról 15 nemzetközi konferencián is beszámoltunk. A kutatásba bekapcsolódott hallgatók eredményeiket a XXVIII. Országos Tudományos Diákköri Konferencián is bemutatják. | The aim of the project was the synthesis of electronically conducting polymer composites and their study by in situ combined electrochemical techniques. The research programme included studies on metal containing composites, incorporation of noble metals, the potential use of inhibitor containing polymer layers in the protection against corrosion, nanostructured composite materials, the conducting behaviour of polypyrrole and polythiophene films doped with nanodispersed metals and oxides, as well as the immobilization of biologically important materials into polymer layers and their use in the realization of electro-biotechnological processes. The results have been published in 8 papers by now, their cumulative impact is about 20, and have been reported at 15 international conferences. The undergraduate students involved in the work present their results also at the XXVIII. National Scientific Conference of Students

Új tulajdonságokat mutató elektronvezető polimerek előállítása és jellemzése = Synthesis and characterization of electronically conducting polymers with new properties

A kutatás témája olyan konjugált polimereken alapuló összetett anyagok előállítása, jellemzése és alkalmazási lehetőségeik feltárása volt, melyek mágneses, termoelektromos vagy fotokatalitikus sajátságokat mutatnak. Megvalósítottuk magnetit nanorészecskék szerves közegbe történő átvitelét, és igazoltuk a magnetit nanorészecskék felületén elhelyezkedő hidroxil- és a karbonsavval szubsztituált tiofének karboxil-csoportja közötti kölcsönhatás kémiai jellegét. A magnetit nanorészecskék felületén megvalósított adszorpciója útján eredményesen építettünk be polipirrol elektródba B12 vitamint. Megvalósítottuk titán-dioxid és szén nanocső kötegeknek vezető polimerekkel történő kombinálását. Kiemelkedő termoelektromos sajátsággal rendelkező 3-alkiltiofének polimerjeit átkristályosítva – nemesfémek beépítése révén – nanoszálas kompozitokat alakítottunk ki. A mintákat átfogóan jellemeztük az anyagtudomány területén általánosan használt technikák (röntgen-diffrakció, spektroszkópiák, elektronmikroszkóp, elektrokémiai nanogravimetria, vezetésmérés) alkalmazásával. Az irodalomban elsőként kidolgoztuk az in situ spektroelektrokémiai és impedanciamérés szimultán alkalmazhatóságát, kimutattuk és értelmeztük a vezetés kialakulásának az egyes töltéshordozókkal való – változó – korrelációját. Felhívtuk a figyelmet az elektronegatív anionok jelenlétében történő elektrokémiai polimerizáció veszélyére, és körültekintő alkalmazásának szükségességére. | During the project, conducting polymer based composites – exhibiting magnetic, thermoelectric or photocatalytic properties - have been synthesized. We realised the transfer of magnetic nanoparticles into organic media, and proved the chemical pattern of the interaction between the hydroxyl group on the surface of the magnetic nanoparticles and the carboxyl group of the acid substituted thiophenes. Exploiting the adsorption of vitamin B12 on the magnetite nanoparticles, its successful incorporation into polypyrrole has been achieved. Composites of conducting polymers with nanotube arrays of titanium dioxide and carbon have been also synthesized. Via re-crystallisation of poly(3-alkylthiophenes) – possessing extraordinary good thermoelectric property – nanofils of composites with noble metals have been prepared. The composites have been characterized widely with XRD, SEM – EDX, EQCM, ac conductance, as well as by diffuse reflection mode, UV-VIS absorption and FTIR – ATR mode spectroscopy. For the first time in the literature, we elaborated the application of in situ spectroelectrochemistry and in situ conductance in a hyphenated mode, and elucidated the background of differences in the correlation between the development of the conductance and the optically distinguishable charge carriers. We called the attention to the potential dangers arising during the electro-polymerisation in the presence of electronegative anions, and to the necessity of its careful consideration

HOW DOES CRYOGENIC FREEZING AFFECT THE CALORIMETRIC PROPERTIES OF LIQUID EGG PRODUCTS?

Eggs are widely utilized because of their high nutrient value, coagulating, foaming, emulsifying and sometimes even colouring or flavouring facilities in food manufacturing. Production of processed egg products shows an increasing trend. Frozen products belong to first processing, their shelf life can increase up to 1 year. By freezing, a large reduction in microbial loss can be achieved. But different undesirable processes can occur. The effect of freezing on animal cells is highly dependent on freezing parameters. It has a different effect on egg subtituents. Egg yolk undergoes a gelation process while proteins can denaturate. In our study pasteurized liquid egg products (liquid egg white, liquid egg yolk and liquid whole egg) were frozen by dripping into liquid nitrogen. After that, a 14-day frozen storage experiment was carried out at -18°C. Before freezing and on the 1th, 7th and 14th days of storage experiment pH, dry matter content, colour and calorimetric properties (denaturation temperatures and enthalpy of denaturation) with differential scanning calorimetry were tested. For statistical analysis, one-way ANOVA (α = 0.05) was employed. In our experiment, we found no significant change in calorimetric properties of liquid egg white after freezing, but significant decreasing of enthalpy and denaturation temperatures of liquid egg yolk and liquid whole egg was identified. In contrast, frozen storage had a decreasing effect in all these products. Freezing caused a clearly visible colour change in LEW, a visible change in colour of LWE and a very clearly visible change in colour of LEY. In case of LEW and LEY changes increased to clearly visible 14 days. In conclusion, our results show that frozen storage had a greater effect on liquid egg products properties than freezing in liquid nitrogen

HOW DOES CRYOGENIC FREEZING AFFECT THE CALORIMETRIC PROPERTIES OF LIQUID EGG PRODUCTS?

Eggs are widely utilized because of their high nutrient value, coagulating, foaming, emulsifying and sometimes even colouring or flavouring facilities in food manufacturing. Production of processed egg products shows an increasing trend. Frozen products belong to first processing, their shelf life can increase up to 1 year. By freezing, a large reduction in microbial loss can be achieved. But different undesirable processes can occur. The effect of freezing on animal cells is highly dependent on freezing parameters. It has a different effect on egg subtituents. Egg yolk undergoes a gelation process while proteins can denaturate. In our study pasteurized liquid egg products (liquid egg white, liquid egg yolk and liquid whole egg) were frozen by dripping into liquid nitrogen. After that, a 14-day frozen storage experiment was carried out at -18°C. Before freezing and on the 1th, 7th and 14th days of storage experiment pH, dry matter content, colour and calorimetric properties (denaturation temperatures and enthalpy of denaturation) with differential scanning calorimetry were tested. For statistical analysis, one-way ANOVA (α = 0.05) was employed. In our experiment, we found no significant change in calorimetric properties of liquid egg white after freezing, but significant decreasing of enthalpy and denaturation temperatures of liquid egg yolk and liquid whole egg was identified. In contrast, frozen storage had a decreasing effect in all these products. Freezing caused a clearly visible colour change in LEW, a visible change in colour of LWE and a very clearly visible change in colour of LEY. In case of LEW and LEY changes increased to clearly visible 14 days. In conclusion, our results show that frozen storage had a greater effect on liquid egg products properties than freezing in liquid nitrogen