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Versatile Synthetic Strategies to Highly Functional Polyesters and Polycarbonates
KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Coating Technology.ORCID iD: 0000-0001-7543-5322
2018 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Polymers have become ubiquitous in today’s society and are found in everything from household items to airplanes and automobiles. Synthetic polymeric materials are as diverse as their applications and their final properties are highly reliant on the building blocks and methods used to assemble them. In the field of biomedical materials, polyesters and polycarbonates have been hailed as excellent materials in large part due to their inherent hydrolytic degradability. With this in mind, careful choice of monomers can ensure that materials not only conform to the desired physical properties, but also elicit a favorable biological response. The utilization of post-polymerization modification of these promising materials has the capability of opening up further avenues to target even more advanced applications. Unfortunately, rigorous and difficult reaction conditions, including multi-step synthesis have to a certain extent held back the adoption of these complex functional materials in applied research. In a pragmatic approach, a sustainable framework was developed in this thesis to seek out more practical methods, limiting the amount of reaction steps and overtly hazardous chemicals.

In a first study, we set out to simplify and scale-up the synthesis of cyclic carbonates with pendant functional groups, capable of undergoing controlled ring-opening polymerization. By avoiding the use of protective-group chemistry we were able two devise a two-step method to create a library of functional monomers. Results in this study show that reactive intermediates could be isolated on 100 g scales, which in a second step was functionalized with a desired alcohol.

With this framework in mind, key practical decisions were made to drastically re-think the work up procedures for greater scalability of bis-MPA dendrimers. In this work, a more efficient, scalable and sustainable approach was devised. Elimination of traditional arduous purification steps led to the synthesis of monodisperse dendrimers up to the sixth generation, with 192 functional groups on 50 g scales. Further work included the omission of protective group-chemistry, using orthogonal functional groups to cut the number of synthetic steps by half.

The know-how developed in the first two projects led us to pursue greater scalability of functional polycarbonates through a simpler polymerization technique. The method allowed the step-growth polymerization of functional materials from more easily accessible monomers isolated on 100 g scales. Subsequent polymerization afforded materials with glass transition temperatures in the range of -45 °C to 169 °C. The method served as a complement to cyclic carbonates, offering a wider range of functional monomers. Furthermore, by careful choice of assembly method, both alternating and scrambled compositions could be achieved.

In a final study, we set out to take advantage of the scrambling mechanism. Control of the final composition of highly rigid degradable polycarbonates was pursued, using renewable building-blocks derived from sugar. In a proof of concept study, thermal and hydrolytic stability of these materials is shown to be dependent on both amount and configuration of each monomer in the final material.

Place, publisher, year, edition, pages
KTH Royal Institute of Technology, 2018. , p. 60
Series
TRITA-CBH-FOU ; 2018:6
National Category
Polymer Chemistry
Identifiers
URN: urn:nbn:se:kth:diva-224754ISBN: 978-91-7729-711-6 (print)OAI: oai:DiVA.org:kth-224754DiVA, id: diva2:1192355
Public defence
2018-04-13, Kollegiesalen, Brinellvägen 8, Stockholm, 10:00 (English)
Opponent
Supervisors
Note

QC 20180322

Available from: 2018-03-22 Created: 2018-03-22 Last updated: 2018-03-22Bibliographically approved
List of papers
1. Reactive imidazole intermediates: simplified synthetic approach to functional aliphatic cyclic carbonates
Open this publication in new window or tab >>Reactive imidazole intermediates: simplified synthetic approach to functional aliphatic cyclic carbonates
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2014 (English)In: Polymer Chemistry, ISSN 1759-9954, E-ISSN 1759-9962, Vol. 5, no 23, p. 6651-6655Article in journal (Refereed) Published
Abstract [en]

Reactive imidazole intermediates based on AB(2) and A(3) monomers, i.e. bis(methylol) propionic acid (bis-MPA) and trimethylolpropane (TMP) have successfully been synthesized and isolated on a 100 gram scale via a facile synthetic protocol using 1,1' -carbonyldiimidazole (CDI) as a key reagent. The robustness of the imidazole intermediates as bench stable precursors enabled the synthesis of a library of functional cyclic carbonates bearing relevant functionalities including hydrophilic PEGs, bioactive cholesterol and clickable groups. A number of functional polycarbonates were obtained by ring-opening polymerization, and their relevance in biomedical applications was highlighted by their low cytotoxicity on human dermal fibroblasts (hDF).

Place, publisher, year, edition, pages
Royal Society of Chemistry, 2014
Keywords
Cyclic carbonates, Synthetic approach
National Category
Polymer Chemistry
Identifiers
urn:nbn:se:kth:diva-157251 (URN)10.1039/c4py00911h (DOI)000344374500003 ()2-s2.0-84908471876 (Scopus ID)
Funder
Knut and Alice Wallenberg Foundation, 2012-0196Swedish Research Council, 2010-453
Note

QC 20141208

Available from: 2014-12-08 Created: 2014-12-08 Last updated: 2018-03-22Bibliographically approved
2. Fluoride-Promoted Esterification with Imidazolide-Activated Compounds: A Modular and Sustainable Approach to Dendrimers
Open this publication in new window or tab >>Fluoride-Promoted Esterification with Imidazolide-Activated Compounds: A Modular and Sustainable Approach to Dendrimers
2015 (English)In: Angewandte Chemie International Edition, ISSN 1433-7851, E-ISSN 1521-3773, Vol. 54, no 8, p. 2416-2419Article in journal (Refereed) Published
Abstract [en]

Based on the growing demand for facile and sustainable synthetic methods to structurally perfect polymers, we herein describe a significant improvement of esterification reactions capitalizing on 1,1-carbonyldiimidazole (CDI). Cesium fluoride was shown to be an essential catalyst for these reactions to reach completion. This approach was successfully applied to the synthesis of structurally flawless and highly functional polyester dendrimers employing traditional and accelerated growth strategies. A sixth generation bis-MPA dendrimer with a molecular weight of 22.080Da and 192 peripheral hydroxy groups was isolated in less than one day of total reaction time. Large quantities of dendrimerswere obtained in high yields (>90%) using simple purification steps under sustainable conditions. The fluoride-promoted esterification (FPE) via imidazolide-activated compounds is wide in scope and constitutes a potentially new approach toward functional polymers and other materials.

Keywords
Accelerated synthesis, Esterification, Fluoride; Imidazole, Polyester dendrimers
National Category
Polymer Chemistry
Identifiers
urn:nbn:se:kth:diva-161958 (URN)10.1002/anie.201411370 (DOI)000350100000019 ()25605503 (PubMedID)2-s2.0-84922800982 (Scopus ID)
Funder
Knut and Alice Wallenberg FoundationMarcus and Amalia Wallenberg FoundationSwedish Research Council, 2011-5358, 2010-435
Note

QC 20150408

Available from: 2015-04-08 Created: 2015-03-20 Last updated: 2018-03-22Bibliographically approved
3. Fluoride-promoted carbonylation polymerization: A facile step-growth technique to polycarbonates
Open this publication in new window or tab >>Fluoride-promoted carbonylation polymerization: A facile step-growth technique to polycarbonates
2017 (English)In: Chemical Science, ISSN 2041-6520, E-ISSN 2041-6539, Vol. 8, no 7, p. 4853-4857Article in journal (Refereed) Published
Abstract [en]

Fluoride-Promoted Carbonylation (FPC) polymerization is herein presented as a novel catalytic polymerization methodology that complements ROP and unlocks a greater synthetic window to advanced polycarbonates. The overall two-step strategy is facile, robust and capitalizes on the synthesis and step-growth polymerization of bis-carbonylimidazolide and diol monomers of 1,3- or higher configurations. Cesium fluoride (CsF) is identified as an efficient catalyst and the bis-carbonylimidazolide monomers are synthesized as bench-stable white solids, easily obtained on 50-100 g scales from their parent diols using cheap commercial 1,1′-carbonyldiimidazole (CDI) as activating reagent. The FPC polymerization works well in both solution and bulk, does not require any stoichiometric additives or complex settings and produces only imidazole as a relatively low-toxicity by-product. As a proof-of-concept using only four diol building-blocks, FPC methodology enabled the synthesis of a unique library of polycarbonates covering (i) rigid, flexible and reactive PC backbones, (ii) molecular weights 5-20 kg mol-1, (iii) dispersities of 1.3-2.9 and (iv) a wide span of glass transition temperatures, from -45 up to 169 °C.

Place, publisher, year, edition, pages
Royal Society of Chemistry, 2017
Keywords
Carbonylation, Fluorine compounds, Glass transition, Monomers, Polycarbonates, Activating reagents, Building blockes, Carbonyldiimidazole, Catalytic polymerization, Efficient catalysts, Growth techniques, Proof of concept, Step-growth polymerizations, Polymerization
National Category
Polymer Chemistry
Identifiers
urn:nbn:se:kth:diva-216581 (URN)10.1039/c6sc05582f (DOI)000404617300018 ()2-s2.0-85021739063 (Scopus ID)
Note

QC 20171101

Available from: 2017-11-01 Created: 2017-11-01 Last updated: 2018-03-22Bibliographically approved
4. Degradable High Tg Sugar Derived Polycarbonates from Isosorbide and Dihydroxyacetone
Open this publication in new window or tab >>Degradable High Tg Sugar Derived Polycarbonates from Isosorbide and Dihydroxyacetone
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2018 (English)In: Polymer Chemistry, ISSN 1759-9954, E-ISSN 1759-9962Article in journal (Refereed) Published
Abstract [en]

Polycarbonates from isosorbide and dihydroxyacetone (DHA) have been synthesised using organocatalytic step-growth polymerization of their corresponding diols and bis-carbonylimidazolides monomers. By choice of feed ratio and monomer activation, either isosorbide or ketal protected DHA, random and alternating poly(Iso-co-DHA) carbonates have been formed. Thermal properties by DSC and TGA were herein strongly correlated to monomer composition. Dilution studies using 1H-NMR of a model compound DHA-diethyl carbonate in acetonitrile and deuterated water highlighted the influence of α-substituents on the keto/hydrate equilibrium of DHA. Further kinetics studies of in the pH* range of 4.7 to 9.6 serve to show the hydrolytic pH-profile of DHA-carbonates. The Hydrolytic degradation of deprotected polymer pellets show an increased degradation with increasing DHA content. Pellets with a random or alternating configuration show different characteristics in terms of mass loss and molecular weight loss profile over time.

National Category
Polymer Chemistry
Identifiers
urn:nbn:se:kth:diva-224753 (URN)10.1039/C8PY00256H (DOI)000431183700004 ()2-s2.0-85046299922 (Scopus ID)
Funder
Swedish Research Council, 2011-5358 2010-435 2015-04779Knut and Alice Wallenberg Foundation, 2012-0196
Note

QC 20180322

Available from: 2018-03-22 Created: 2018-03-22 Last updated: 2018-05-15Bibliographically approved

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