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Dendrimers and dendronized polymers: synthesis and characterization
KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
2006 (English)Doctoral thesis, comprehensive summary (Other scientific)
Abstract [en]

The goal of this work was to synthesize complex macromolecular architectures such as dendrimers and dendronized polymers, and evaluate the effect from the dendrons on the optical and material properties. The work presented in this doctoral thesis, Dendrimers and Dendronized Polymers - Synthesis and Characterization, is divided into one minor and one major part. The first part deals with the synthesis and characterization of two sets of dendritic porphyrins based on 2,2-bis(methylol)propionic acid (bis-MPA). The second part deals with the synthesis and characterization of dendronized poly(hydroxyl ethyl methacylate), dendronized poly(norbornene), and dendronized triblock copolymers, were the pendant dendrons are based on bis-MPA.

Both free-base and zinc containing dendritic porphyrins was synthesized up to the fifth generation by employing iterative ester coupling utilizing the acetonide protected anhydride of bis-MPA as generic building block.

First and second generation dendron bearing methacrylates based on 2-hydroxyethyl methacrylate were also synthesized by utilizing the acetonide protected anhydride of bis-MPA, and subsequently polymerized by atom transfer radical polymerization. By adopting a divergent “graft-to” approach starting from the first generation dendronized poly(hydroxyl ethyl methacrylate), well-defined dendronized polymers with acetonide, hydroxyl, acetate and hexadecyl surface functionality were obtained.

By utilizing the same divergent iterative esterfication, first to fourth generation dendron functionalized norbornenes were synthesized. These monomers were polymerized by ring-opening metathesis polymerization, utilizing either Grubbs´ first or second generation catalyst.

Acrylate functional first to fourth generation monomers were synthesized by the copper(I) catalyzed “click” coupling of azido functional dendrons and propargyl acrylate. The monomers were polymerized to dendronized triblock copolymers by reversible addition-fragmentation chain transfer polymerization, utilizing a difunctional poly(methyl methacrylate) as macro chain transfer agent.

The bulk properties of the dendronized poly(hydroxyl ethyl methacrylate) and poly(norbornene) were investigated by dynamic rheological measurements and differential scanning calorimetry. It was found that all the acetonide functional bis-MPA based dendronized polymers had glass transitions temperatures in a similar range. The rheological behaviour showed that for the dendronized polymers having the same backbone length the complex viscosity as a function of functionality was independent of the surface functionality of the polymer. The generation number of the polymer had a profound influence on the complex viscosity, changing form a Newtonian behaviour to a shear thinning behaviour when the generation of the dendrons was increased from two to four. The dendronized poly(norbornene) had increasingly shorter backbone lengths for each generational increase, and for the materials set with comparably lower degree of polymerization, the G’ part of the complex modulus was mostly affected by attaching larger dendrons. In the case of the sample set of higher degree of polymerization, the second, third, and fourth generation samples had similar slopes of the G’ and G” curves, indicating a similar relaxation behaviour.

Place, publisher, year, edition, pages
Stockholm: KTH , 2006. , 66 p.
Series
Trita-FPT-Report, ISSN 1652-2443 ; 2006:10
Keyword [en]
Dendrimers, dendronized polymers, atom transfer radical polymerisation, ring-opening metathesis polymerization, reversible addition-fragmentation chain transfer polymerization, 2, 2-bis(methylol)propionic acid, tri-block copolymers, rheology, differential scanning calorimerty, 1H-NMR self-diffusion
National Category
Polymer Chemistry
Identifiers
URN: urn:nbn:se:kth:diva-3970ISBN: 91-7178-333-4 (print)OAI: oai:DiVA.org:kth-3970DiVA: diva2:10222
Public defence
2006-06-02, D2, Lindstedsvägen 5, Stockholm, 10:00
Opponent
Supervisors
Note
QC 20100914Available from: 2006-05-17 Created: 2006-05-17 Last updated: 2010-09-14Bibliographically approved
List of papers
1. Porphyrin-Cored 2,2-Bis(methylol)propionic Acid Dendrimers
Open this publication in new window or tab >>Porphyrin-Cored 2,2-Bis(methylol)propionic Acid Dendrimers
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2004 (English)In: Chemistry of Materials, ISSN 0897-4756, E-ISSN 1520-5002, Chemistry of materials, Vol. 16, no 14, 2794-2804 p.Article in journal (Refereed) Published
Abstract [en]

The synthesis and characterization of dendron-coated porphyrins up to the fifth generation are described. Both free base and zinc-cored tetraphenylporphyrin (TPPH2 and TPPZn) were used, from which the dendrons were divergently grown using the anhydride of acetonide-protected bis-MPA (acetonide-2,2-bis(methoxy)propanoic anhydride). It is shown that a spacer must be attached to the porphyrin to increase the hydrolytic stability and allow synthesis of higher generations. Direct coupling of dendrons to the porphyrins was also investigated but failed to give full substitution of the porphyrin core. The absorption and fluorescence emission data for the TPPZn dendrimers indicate that the porphyrin configuration may change at higher generations. The hydrodynamic volume of the dendrimers is calculated from the polarization anisotropy decay data. It is shown that these bis-MPA dendrimers are significantly smaller than the same generation Frechet-type benzyl ether TPP dendrimer.

Keyword
photoinduced electron-transfer, dendritic polyglutamic porphyrins, site isolation, zinc porphyrin, poly(amide) dendrimers, 3rd-order nonlinearity, efficient synthesis, metal-complexes, star polymers, metalloporphyrins
National Category
Chemical Sciences
Identifiers
urn:nbn:se:kth:diva-5743 (URN)10.1021/cm035354e (DOI)000222550600018 ()2-s2.0-3142676514 (Scopus ID)
Note
QC 20100914Available from: 2006-05-17 Created: 2006-05-17 Last updated: 2011-09-26Bibliographically approved
2. Dendronized polymers with tailored surface groups
Open this publication in new window or tab >>Dendronized polymers with tailored surface groups
2005 (English)In: Journal of Polymer Science Part A: Polymer Chemistry, ISSN 0887-624X, E-ISSN 1099-0518, Vol. 43, no 17, 3852-3867 p.Article in journal (Refereed) Published
Abstract [en]

A series of polymers tethered with bis-MPA dendrons was synthesized by a combination of divergent growth and atom transfer radical polymerization (ATRP). Macromonomers of first and second generation were synthesized utilizing the acetonide protected anhydride of bis-MPA as the generic esterfication agent. The macromonomers were polymerized in a controlled fashion by ATRP utilizing Cu(I)/Cu(II) and N-propyl-2-pyridylmethanamine as the halogen/ligand system. The end-groups of these polymers were further tailored to achieve hydroxyl, acetate, and aliphatic hexadecyl functionality. With this approach all polymers will emanate from the same backbone, enabling for an evaluation of both the generation and end-group dependent properties. Furthermore, a dendronized tri-block copolymer was synthesized. All materials were analyzed by H-1 and C-13 NMR, as well as size-exclusion chromatography (SEC). The SEC analysis revealed that the molecular weights of the divergently grown dendronized polymers increased with increasing generation while the polydispersity (PDI) was kept low.

Keyword
atom transfer radical polymerization (ATRP), block copolymers, dendronized polymers, macromonomers, 2, 2-bis(methylol) propionic acid (bis-MPA)
National Category
Polymer Chemistry
Identifiers
urn:nbn:se:kth:diva-5744 (URN)10.1002/pola.20846 (DOI)000231369700015 ()2-s2.0-26944487280 (Scopus ID)
Note
QC 20100907Available from: 2006-05-17 Created: 2006-05-17 Last updated: 2010-12-16Bibliographically approved
3. Bulk Properties of Dendronized Polymers with Tailored End-groups emanating from the same Backbone
Open this publication in new window or tab >>Bulk Properties of Dendronized Polymers with Tailored End-groups emanating from the same Backbone
2005 (English)In: Journal of Polymer Science Part A: Polymer Chemistry, ISSN 0887-624X, E-ISSN 1099-0518, Vol. 43, no 19, 4496-4504 p.Article in journal (Refereed) Published
Abstract [en]

Dendronized polymers with a methacrylate backbone bearing pendant aliphatic polyester dendrons based on 2,2-bis(methylol)propionic acid have been investigated by rheological measurements, differential scanning calorimetry (DSC), size exclusion chromatography (SEC), and H-1 NMR self-diffusion techniques. The change in material properties due to the attachment of larger dendrons and/or different end-groups to a backbone of the same length is investigated. Dendronized polymers of the second to fourth generation with hydroxyl, acetonide, or hexadecyl end-group functionalities have been studied. DSC revealed that the glass transition temperature of the amorphous polymers increases with increasing size of the dendrons, and that the ability for the hexadecyl functional polymers to crystallize decreases with increasing size of dendrons. H-1 NMR self-diffusion and longitudinal relaxation data are consistent with an elongated rod-like model of the polymers in solution. Larger dendrons lead to a larger rod diameter that approximately double when increasing the generation of dendronized polymer from two to four. Rheological measurements demonstrated that the complex viscosity at low frequency increased with dendron size. Independently of the functionality, the second and third generation samples initially showed a Newtonian plateau, followed by a shear thinning region at higher frequencies. The fourth generation samples only showed shear thinning over the whole frequency region.

Keyword
dendronized polymer, size exclusion chromatography, 1H NMR self-diffusion, differential scanning calorimetry, rheology
National Category
Chemical Sciences
Identifiers
urn:nbn:se:kth:diva-5745 (URN)10.1002/pola.20918 (DOI)000231989400018 ()2-s2.0-27744489363 (Scopus ID)
Note
QC 20100901Available from: 2006-05-17 Created: 2006-05-17 Last updated: 2010-12-16Bibliographically approved
4. Characterization of Poly(norbornene) Dendronized Polymers Prepared by Ring-Opening Metathesis Polymerization of Dendron Bearing Monomers
Open this publication in new window or tab >>Characterization of Poly(norbornene) Dendronized Polymers Prepared by Ring-Opening Metathesis Polymerization of Dendron Bearing Monomers
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2006 (English)In: Macromolecules, ISSN 0024-9297, E-ISSN 1520-5835, Vol. 39, no 21, 7241-7249 p.Article in journal (Refereed) Published
Abstract [en]

The preparation and characterization of a series of first to fourth generation dendronized poly-(norbornene)s are presented. The monomers were synthesized in a divergent fashion from 5-norbornene-2-methanol, utilizing the acetonide protected anhydride of 2,2-bis(methylol)propionic acid. The norbornenyl bearing dendrons were polymerized by ring-opening metathesis polymerization, and it was found that the Grubbs' first generation catalyst resulted in polymers with lower polydispersity compared to the materials obtained when employing the second generation catalyst. Two series of first to fourth generation polymers were characterized by DSC, SEC, and dynamic rheological measurements. In addition, it was found that the fourth generation material could form regular, porous membranes and birefringent fibers. The membranes were characterized with atomic force and optical microscopy. The birefringent fibers were analyzed with X-ray diffraction, polarized FTIR, and polarized optical microscopy.

Keyword
Carboxylic acids, Catalyst activity, Composition, Monomers, Ring opening polymerization, Synthesis (chemical)
National Category
Chemical Sciences
Identifiers
urn:nbn:se:kth:diva-5746 (URN)10.1021/ma061147z (DOI)000241106900013 ()2-s2.0-33751345396 (Scopus ID)
Note
QC 20100902. Uppdaterad från Submitted till Published (20100902)Available from: 2006-05-17 Created: 2006-05-17 Last updated: 2010-09-02Bibliographically approved
5. Dendronized ABA Triblock copolymers by Reversible Addition-Fragmentation Transfer Polymerization
Open this publication in new window or tab >>Dendronized ABA Triblock copolymers by Reversible Addition-Fragmentation Transfer Polymerization
2006 (English)Manuscript (preprint) (Other academic)
National Category
Polymer Chemistry
Identifiers
urn:nbn:se:kth:diva-5747 (URN)
Note

QC 20100914

Available from: 2006-05-17 Created: 2006-05-17 Last updated: 2016-05-24Bibliographically approved
6. Solution Properties of Dendronized Poly(Hydroxy Ethyl Methacrylate) Polymers
Open this publication in new window or tab >>Solution Properties of Dendronized Poly(Hydroxy Ethyl Methacrylate) Polymers
2006 (English)In: Journal of Polymer Science Part A: Polymer Chemistry, ISSN 0887-624X, E-ISSN 1099-0518, Vol. 44, no 11, 3674-3683 p.Article in journal (Refereed) Published
Abstract [en]

Four generations of dendronized polymers with a methacrylate backbone and hydroxy-functionalized aliphatic polyester dendrons based on 2,2-bis(methylol)propionic acid were studied in solutions by rheological measurements, dynamic light scattering, turbidimetry, and H-1 NMR self-diffusion measurements to reveal the effect of increasing hydrophilicity and molecular size on their solution properties. The studied polymers were interesting new amphiphiles with a hydrophobic main chain and a hydrophilic shell. Evidence of aggregation upon the heating of the first-generation polymer in an aqueous solution was obtained by dynamic light scattering and turbidimetry, reflecting the effect of the hydrophobic polymer backbone, whereas the higher generation polymers did not show aggregation upon heating. Although the dimensions of the polymers were observed to increase with increasing generation, all the polymers exhibited low viscosities and Newtonian flow behavior in both aqueous and dimethyl sulfoxide solutions. The relative viscosities of the polymers in water and dimethyl sulfoxide showed that the conformation of the polymers was somewhat more open in dimethyl sulfoxide, and this led to higher viscosities than those in water, in agreement with the H-1 NMR diffusion measurements, by which the dimensions were found to be larger for the polymers dissolved in dimethyl sulfoxide.

Keyword
dendrimers, NMR; viscosity, water-soluble polymers
National Category
Polymer Chemistry
Identifiers
urn:nbn:se:kth:diva-5748 (URN)10.1002/pola.21471 (DOI)000237704000024 ()2-s2.0-33744832419 (Scopus ID)
Note
QC 20100914Available from: 2006-05-17 Created: 2006-05-17 Last updated: 2010-09-14Bibliographically approved

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