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Dendronized polymers with tailored surface groups
KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.ORCID iD: 0000-0002-9372-0829
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.

Place, publisher, year, edition, pages
2005. Vol. 43, no 17, 3852-3867 p.
Keyword [en]
atom transfer radical polymerization (ATRP), block copolymers, dendronized polymers, macromonomers, 2, 2-bis(methylol) propionic acid (bis-MPA)
National Category
Polymer Chemistry
Identifiers
URN: urn:nbn:se:kth:diva-5744DOI: 10.1002/pola.20846ISI: 000231369700015Scopus ID: 2-s2.0-26944487280OAI: oai:DiVA.org:kth-5744DiVA: diva2:10217
Note
QC 20100907Available from: 2006-05-17 Created: 2006-05-17 Last updated: 2010-12-16Bibliographically approved
In thesis
1. Dendrimers and dendronized polymers: synthesis and characterization
Open this publication in new window or tab >>Dendrimers and dendronized polymers: synthesis and characterization
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
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:nbn:se:kth:diva-3970 (URN)91-7178-333-4 (ISBN)
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
2. Synthesis and characterization of dendritic architectures
Open this publication in new window or tab >>Synthesis and characterization of dendritic architectures
2005 (English)Licentiate thesis, comprehensive summary (Other scientific)
Abstract [en]

The goal of this work was to synthesize different dendritic architectures and evaluate the effect from the dendrons on the material properties. The work presented in this licentiate thesis, Synthesis and Characterization of Dendritic Architectures, is divided into major parts. 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 a series of dendronized polymers based on bis-MPA.

Both free-base and zinc containing dendritic porphyrins were synthesized up to the fifth generation utilizing the acetonide protected anhydride of bis-MPA. The resulting dendrimers were characterized by SEC, NMR, and MALDI-TOF. The dendrimers were found to be well-defined, virtually monodisperse, molecules up to the fourth generation. In the case of the fifth generation dendrimers, some structural defects were observed. The hydrodynamic volume (in THF) of these molecules was calculated using the rotational correlation time, and they were found to be more compact than the corresponding Fréchet-type dendrimers of the same generation.

Macromonomers of the first and second generation were also synthesized utilizing the acetonide protected anhydride of bis-MPA and subsequently polymerized by atom transfer radical polymerization, using a system of N-propyl-2-pyridylmethanamine, Cu(I)Br, and Cu(I)Br2. This system resulted in well-controlled polymerizations with low polydispersity polymers. By adopting a divergent ‘graft-to’ approach, welldefined dendronized polymers with acetonide, hydroxyl, acetate, and hexadecyl functionality respectively, were obtained.

The bulk properties of the dendronized polymers were investigated by differential scanning calorimetry, dynamic-mechanical measurements, and 1H-NMR selfdiffusion. It was found that that increasing the size of the pendant dendron increased the glass transition temperature of the materials. The degree of crystallization of the hexadecyl functional materials was found to decrease with dendron size, most likely due to the reduced flexibility of the backbone prohibiting effective crystallization. The dynamic mechanical measurements revealed that the behavior of the complex viscosity as a function of frequency was independent of functionality. The second and third generation materials were found to have a Newtonian plateau up to a frequency where they become shear-thinning. The fourth generation materials were found to be shearthinning in the frequency range. 1H-NMR self-diffusion measurements revealed that the shape of the acetonide functional dendronized polymers in solution was best described by using a rod-like or prolated ellipsoid model.

Place, publisher, year, edition, pages
Stockholm: KTH, 2005. 47 p.
Series
Trita-FPT-Report, ISSN 1652-2443 ; 2005:10
Keyword
Biochemistry, Biokemi
National Category
Chemical Sciences
Identifiers
urn:nbn:se:kth:diva-283 (URN)
Presentation
2005-04-28, sal H1, 10:00
Supervisors
Note
QC 20101216Available from: 2005-07-06 Created: 2005-07-06 Last updated: 2010-12-16Bibliographically approved

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