Authors:	Hilf, Jeannette
Title:	Functional polycarbonates from carbon dioxide and tailored epoxide building blocks
Online publication date:	28-Jun-2016
Year of first publication:	2016
Language:	english
Abstract:	Carbon dioxide (CO2), an industrial waste product, is a potentially interesting C1 feedstock, as it is nontoxic, renewable, abundant and inexpensive. A promising approach for the use of CO2 is its polymerization to polycarbonates (PC), by catalytic copolymerization of epoxides. A current drawback for many applications of the resulting materials is the low number of pendant functional groups at the PC backbone. The catalytic copolymerization of CO2 with appropriately substituted epoxides is an ideal platform for the generation of multifunctional PCs. This thesis aims at the development of the synthesis multifunctional polymer architectures based epoxide/carbon dioxide copolymerization. The work is motivated both by fundamental issues and application potential of the resulting materials. Chapter 1 gives an introduction to this thesis. Chapter 1.1 reviews the current state of the art in the synthesis of functional polycarbonates from carbon dioxide and tailored epoxide building blocks. Different monomers such as cyclohexene oxide derivatives; propylene oxide derivatives; glycidyl ethers; and cyclic anhydrides or cyclic esters are compared and discussed with respect to the incorporation of different functionalities. Chapter 1.2 discusses catalysts and gives insights into the mechanism of the alternating copolymerization of carbon dioxide and epoxides with various substituents Chapter 2 examines the synthesis and selected applications of different poly(propylene carbonate) architectures. In Chapter 2.1, blockcopolymer approach is described to synthesize CO2-based nonionic surfactants. Copolymerization of CO2 and propylene oxide (PO) has been employed to generate amphiphilic polycarbonate block copolymers with a hydrophilic poly(ethylene glycol) (PEG) block and an apolar poly(propylene oxide) (PPC) block. Furthermore the controlled synthesis of multi-arm star polyether-polycarbonate polyols based on propylene oxide and CO2 is presented in Chapter 2.2. It has been shown that flexible multi-arm star polymers with PPC arms can be prepared using a hyperbranched poly-(propylene oxide) copolymer with glycerol branching points as a multifunctional initiator for the controlled catalytic copolymerization of carbon dioxide with propylene oxide. Notably, the post-polymerization functionalization of the hydroxyl end groups with phenylisocyanate was shown to be highly efficient and occurred without observable backbone degradation, enabling the potential use of the multifunctional PPC polymers as flexible, non-crystalline polycarbonate polyols for polyurethanes. Chapter 3 describes the synthesis of functional polycarbonates using glycidyl ether monomers. Glycidyl ethers are readily available and can easily be synthesized from epichlorohydrin and a desired alcohol. Functional groups that are distributed randomly at the polymer backbone can be employed to tailor the chemical properties of the materials, such as hydrophilicity/hydrophobicity, biocompatibility, and biodegradability as well as general material properties. In order to prevent side reactions and catalyst poisoning, the functional groups in the monomers are usually protected prior to polymerization, and must be easy to remove after polymerization, with no or very little alteration to the polymer chains. In Chapter 3.1 hydroxyl-functional aliphatic polycarbonates are presented, which can be prepared directly from CO2 and glycidyl ethers with protected functionalities. 1,2-Isopropylidene glyceryl glycidyl ether as a protected diol and glycidyl methyl ether (GME) have been copolymerized with CO2, using a readily available Zn-pyrogallol catalyst system. The resulting functional polycarbonates are promising materials, e.g., as degradable supports for catalysts, drugs or reagents. In addition, the hitherto synthetically inaccessible functional, aliphatic poly(1,2-glycerol carbonate) as a fundamental, simple polymer structure based on glycerol and CO2 as building units is presented in Chapter 3.2 and Chapter 3.3. The material was obtained by two-step procedures either from copolymerization of ethoxy ethyl glycidyl ether (EEGE) or benzyl glycidyl ether (BGE) with CO2, followed by deprotection via acidic cleavage or hydrogenation, respectively. The removal of either protecting group was possible without backbone degradation. Using different easily available functional glycidyl ethers various other functionalities, e.g., triple bonds and furfuryl groups can also be introduced in polycarbonates for subsequent click-reactions (Chapter 3.4 and Chapter 3.5). Chapter 4 describes the synthesis of functional polycarbonates with propylene oxide-based epoxide monomers.
DDC:	540 Chemie 540 Chemistry and allied sciences
Institution:	Johannes Gutenberg-Universität Mainz
Department:	FB 09 Chemie, Pharmazie u. Geowissensch.
Place:	Mainz
ROR:	https://ror.org/023b0x485
DOI:	http://doi.org/10.25358/openscience-4069
URN:	urn:nbn:de:hebis:77-diss-1000005474
Version:	Original work
Publication type:	Dissertation
License:	In Copyright
Information on rights of use:	https://rightsstatements.org/vocab/InC/1.0/
Extent:	320 Seiten
Appears in collections:	JGU-Publikationen