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Synthesis, characterization and molecular architecture of electroactive and degradable polymers
KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
2010 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

The third-generation biomaterials are designed to stimulate specific cellular responses at the molecular level. Recent studies have shown that electrical signals regulate cellular activities including cell adhesion, migration, proliferation and differentiation. One of the biggest limitations for conductive polymers in tissue engineering applications is their inherent inability to degrade, so the incorporation of conducting polymers into biodegradable polymers to obtain electroactive and biodegradable materials is still a challenge. Architecture plays an important role on the performance of polymers. To achieve the optimal mechanical, degradation, thermal and biological properties for each biomedical application, it is desirable to promote architectural diversity.

 

To combine the electroactivity of conductive polymers and the degradability of aliphatic polyesters, linear, star-branched and hyperbranched copolymers based on Poly(L,L-lactide) (PLLA), Poly(ε-caprolactone) (PCL), and aniline oligomers were synthesized by coupling reactions between the hydroxyl group at the chain end of the PLLAs or PCLs and the carboxyl group of the aniline oligomer, using the N, N’-dicyclohexyl carbodiimide / 4-dimethylaminopyridine (DCC/DMAP) catalytic system. The chemical structures of the polymers obtained were fully characterized by Fourier transform infrared spectroscopy, nuclear magnetic resonance, and size exclusion chromatography. The cyclic voltammetry and ultraviolet spectra of the copolymers demonstrated their good electroactive properties. Differential scanning calorimetry and thermogravimetric analysis studies showed the copolymers were more thermal stable than the corresponding PLLAs and PCLs. The wettability of the copolymer film increased sharply after doping with acid. The copolymers also exhibit much better processibility than conductive polymers because they are soluble in most organic solvents.

 

Macromolecular architecture design as a useful tool to enhance the conductivity of degradable polymers has been presented. The hyperbranched copolymers showed a higher conductivity than that of the linear ones with the same content of conductive segments. It is proposed that the higher conductivity of the hyperbranched copolymers is due to the ordered distribution of peripheral emeraldine state of aniline pentamer (EMAP) segments. Thus, the conductivity of the polymers is controlled by the macromolecular design. In other words, the conductivity of the polymers was increased with the same content of aniline oligomer by macromolecular architecture.

The copolymers with different architectures could be used to tailor the thermal properties, degradation properties and surface properties, to give materials that are favorable for the growth of electrically excitable cells in tissue engineering.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2010. , 41 p.
Series
Trita-CHE-Report, ISSN 1654-1081 ; 2010:24
Keyword [en]
Poly(L, L-lactide), poly(ε-caprolactone), ring-opening polymerization, carboxyl-capped aniline trimer, carboxyl-capped aniline pentamer, coupling reaction, DCC/DMAP system, degradability, electroactivity, conductivity, macromolecular architecture, tissue engineering
National Category
Polymer Chemistry
Identifiers
URN: urn:nbn:se:kth:diva-12868ISBN: 978-91-7415-669-0 (print)OAI: oai:DiVA.org:kth-12868DiVA: diva2:319454
Presentation
2010-06-10, E2, Lindstedsvägen 3, Stockholm, 10:00 (English)
Opponent
Supervisors
Note

QC 20100519

Available from: 2010-05-19 Created: 2010-05-18 Last updated: 2012-12-18Bibliographically approved
List of papers
1. Molecular Achitecture of electroactive and biodegradable copolymers composed of polyactide and carboxyl-capped aniline trimer
Open this publication in new window or tab >>Molecular Achitecture of electroactive and biodegradable copolymers composed of polyactide and carboxyl-capped aniline trimer
2010 (English)In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 11, no 4, 855-863 p.Article in journal (Refereed) Published
Abstract [en]

wo-, four-, and six-armed branched copolymers with electroactive and biodegradable properties were synthesized by coupling reactions between poly(l-lactides) (PLLAs) with different architecture and carboxyl-capped aniline trimer (CCAT). The aniline oligomer CCAT was prepared from amino-capped aniline trimer and succinic anhydride. FT-IR, NMR, and SEC analyses confirmed the structure of the branched copolymers. UV−vis spectra and cyclic voltammetry of CCAT and copolymer solution showed good electroactive properties, similar to those of polyaniline. The water contact angle of the PLLAs was the highest, followed by the undoped copolymer and the doped copolymers. The values of doped four-armed copolymers were 54−63°. Thermal properties of the polymers were studied by DSC and TGA. The copolymers had better thermal stability than the pure PLLAs, and the Tg between 48−58 °C and Tm between 146−177 °C of the copolymers were lower than those of the pure PLLA counterparts. This kind of electroactive and biodegradable copolymer has a great potential for applications in cardiovascular or neuronal tissue engineering.

National Category
Polymer Chemistry
Identifiers
urn:nbn:se:kth:diva-12931 (URN)10.1021/bm9011248 (DOI)000276557300004 ()2-s2.0-77950826113 (Scopus ID)
Funder
Swedish Research Council, 2008-5538
Note
QC 20100519Available from: 2010-05-19 Created: 2010-05-19 Last updated: 2017-12-12Bibliographically approved
2. Enhanced Electrical Conductivity by Macromolecular Architecture: Hyperbranched Electroactive and Degradable Block Copolymers Based on Poly(epsilon-caprolactone) and Aniline Pentamer
Open this publication in new window or tab >>Enhanced Electrical Conductivity by Macromolecular Architecture: Hyperbranched Electroactive and Degradable Block Copolymers Based on Poly(epsilon-caprolactone) and Aniline Pentamer
2010 (English)In: Macromolecules, ISSN 0024-9297, E-ISSN 1520-5835, Vol. 43, no 10, 4472-4480 p.Article in journal (Refereed) Published
Abstract [en]

We present macromolecular architecture design as a useful tool to enhance the conductivity of degradable polymers. Linear and hyperbranched copolymers with electrical conductivity and biodegradability were synthesized by an "A(2) + B-n (n=2, 3, 4)" strategy using carboxyl-capped aniline pen tamer (CCAP) and branched poly(epsilon-caprolactone)s (PCLs) by coupling reactions. A more hydrophilic surface and lower crystallinity of the doped emeraldine state of aniline pentamer (EM A P) copolymer was achieved compared with PCLs, and TGA results demonstrated that the CCAP contents in the copolymers were almost the same. The structure of the polymers was characterized by FT-IR. NMR, and SEC. Good electroactivity of the copolymers was confirmed by UV and cyclic voltammetry (CV), and CV showed three pairs of redox peaks. The hyperbranched copolymers had a higher conductivity than the linear ones. It is suggested that the higher conductivity of the hyperbranched copolymer is due to the ordered distribution of peripheral EMAP segments that more easily form a conductive network. Therefore, the conductivity of the polymers is improved and controlled by the macromolecular architecture.

National Category
Polymer Chemistry
Identifiers
urn:nbn:se:kth:diva-27872 (URN)10.1021/ma100530k (DOI)000277649500010 ()2-s2.0-77952475689 (Scopus ID)
Funder
Swedish Research Council, 2008-5538
Note
QC 20110112Available from: 2011-01-12 Created: 2011-01-03 Last updated: 2017-12-11Bibliographically approved

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