h1

TY  - THES
AU  - He, YingChun
TI  - From cyclic carbonate bifunctional couplers to amphiphilic poly(ethylene imine)s
CY  - Aachen
PB  - Publikationsserver der RWTH Aachen University
M1  - RWTH-CONV-124352
SP  - VIII, 274 S. : graph. Darst.
PY  - 2012
N1  - Aachen, Techn. Hochsch., Diss., 2012
AB  - This dissertation is concerned with two subjects: bifunctional couplers and multifunctional poly(ethylene imine)s (Figure 1). Bifunctional couplers discussed in this thesis are mostly bearing at least one five-membered ring carbonate. These bifunctional couplers were suitable for the selective combination of two functional primary amines. Via addition or substitution reactions of bifunctional couplers with functional amines, functional couplers with different properties bearing a five-membered ring carbonate were obtained. These functional couplers were used to prepare tailor made multifunctional poly(ethylene imine)s by ring-opening reaction of functional five-membered ring carbonates with poly(ethylene imine)s. Based on the chemistry of cyclic carbonates, phenyl carbonate, chloroformates, and epoxides, in total 10 bifunctional couplers (A1-A5, B1-B3, C1-C2, and BC56) with different coupling concepts – substitution/addition or addition/addition – were synthesized (Figure 2). Their reactivity and selectivity towards amines were studied. The hydrolytic stability of BC56 and functional couplers synthesized from BC56 were tested. In the ring opening reaction of cyclic carbonates with amines, urethane groups with an adjacent hydroxyl group were formed. The modification of these hydroxyl groups were studied in chapter 4. The application of bifunctional coupler BC56 for the synthesis of hydroxyl functional polyurethanes was discussed in chapter 3. Functional cyclic carbonates prepared from A1 – A4 were used for the modification of poly(ethylene imine)s. Multifunctional poly(ethylene imine)s bearing functional groups such as hydrophobic chains of various lengths, hydrophilic groups, cationic (ammonium) groups, amphiphilic groups, and/or labeling groups (pyrene) were synthesized und characterized. Multifunctional poly(ethylene imine)s can be obtained in one-step synthesis or in sequential addition synthesis by reaction with different kind of functional cyclic carbonates. The influence of the preparation process on their microstructure and antimicrobial properties was studied in chapter 6. In the antimicrobial process, cationic and hydrophobic functional groups interact both with the bacterial membrane. The way of cationic and hydrophobic groups linked to each other and linked on the poly(ethylene imine) molecules influenced the antimicrobial efficiency of the cationic/hydrophobic modified small compounds and poly(ethylene imine)s (chapter 7). In order to study the absorption of multifunctional poly(ethylene imine)s on negatively charged surfaces, single molecules of multifunctional poly(ethylene imine)s were visualized on mica substrates via atomic force microscopy (AFM) (in chapter 5). The properties of multifunctional poly(ethylene imine)s in thin layers and in water solution and their hydrolytic and thermal stability were investigated in chapter 8.
KW  - Bifunktionelle Verbindungen (SWD)
KW  - Fünfringverbindungen (SWD)
KW  - Cyclische Verbindungen (SWD)
KW  - Carbonate (SWD)
LB  - PUB:(DE-HGF)11
UR  - https://publications.rwth-aachen.de/record/62855
ER  -