Reverzibilno zamrežen poliuretan s pinakolno vezjo
Namen naloge je predstaviti reverzibilno zamrežene poliuretane z aromatsko pinakolno enoto, ki vsebuje reverzibilno C-C vez. V obravnavani študiji so znanstveniki sintetizirali PU na osnovi pinakola (P1) ter za potrditev lastnosti P1 sintetizirali in testirali še podobne poliuretane (P2, P3), ki pa se med seboj razlikujejo v sestavi in po lastnostih. Visoko žilavost PU na osnovi pinakola pripisujejo visoki energiji C-C vezi, ki pada z dolžino vezi zaradi elektronskih in steričnih učinkov. V zmernih pogojih (primerna aktivacijska energija cepitve vezi) se vezi v PU na osnovi pinakola lahko razcepijo in znova povežejo. Mešanje in preurejanje mrež vodi v celjenje razpok. Temperatura steklastega prehoda poliuretana P1 je bila določena z dinamično mehansko analizo (DMA) preko izračuna modula (elastični E', viskozni E'') materiala in tan δ. Ugotovljeno je bilo, da za reverzibilno reakcijsko procesiranje P1 ni potrebna kontrola temperature. Najpomembnejši korak pri sintezi stimulativno odzivnega polimera P1 je bil predhodna sinteza hidroksi funkcionaliziranega aromatskega pinakola ter njegova vključitev v zamrežen poliuretan.
The aim of the thesis is to present reversibly crosslinked polyurethanes with an aromatic pinacol unit containing a reversible C-C bond. In the study in question, the scientists synthesized PU based on pinacol (P1) and synthesized and tested similar polyurethanes (P2, P3) to confirm the properties of P1, but they differ in composition and properties. The high toughness of pinacol-based PUs is attributed to the high energy of the C-C bond, which decreases with bond length due to electronic and steric effects. Under moderate conditions (appropriate bond cleavage activation energy), the bonds in a pinacol-based PU can split and reconnect. Mixing and rearranging the nets leads to the healing of the cracks. The glass transition temperature of polyurethane P1 was determined by dynamic mechanical analysis (DMA) through the calculation of the modulus (elastic E', viscous E'') of the material and tan δ. It was found that no temperature control is required for reversible P1 reaction treatment. The most important step in the synthesis of the stimulus-responsive polymer P1 was the preliminary synthesis of hydroxy-functionalized aromatic pinacol and its incorporation into cross-linked polyurethane.
2020
2020-09-09 11:10:01
1060
polimer, poliuretan, zamrežen, pinakolna vez
polymer, polyurethane, crosslinked, pinacol bond
mb11
Miha
Mihovec
70
Urška
Šebenik
991
VisID
16
9041
COBISS_ID
3
28028163
Mihovec Miha - Reverzibilno zamrežen poliuretan s pinakolno vezjo.pdf
1550636
Predstavitvena datoteka
2020-09-09 11:10:08