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Molecular Achitecture of electroactive and biodegradable copolymers composed of polyactide and carboxyl-capped aniline trimer
KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.ORCID iD: 0000-0002-1922-128X
KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
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.

Place, publisher, year, edition, pages
2010. Vol. 11, no 4, 855-863 p.
National Category
Polymer Chemistry
Identifiers
URN: urn:nbn:se:kth:diva-12931DOI: 10.1021/bm9011248ISI: 000276557300004Scopus ID: 2-s2.0-77950826113OAI: oai:DiVA.org:kth-12931DiVA: diva2:319690
Funder
Swedish Research Council, 2008-5538
Note
QC 20100519Available from: 2010-05-19 Created: 2010-05-19 Last updated: 2011-11-23Bibliographically approved
In thesis
1. Synthesis, characterization and molecular architecture of electroactive and degradable polymers
Open this publication in new window or tab >>Synthesis, characterization and molecular architecture of electroactive and degradable polymers
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
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:nbn:se:kth:diva-12868 (URN)978-91-7415-669-0 (ISBN)
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
2. degradable electroactive polymers: Synthesis, Macromolecular architecture and scaffold design
Open this publication in new window or tab >>degradable electroactive polymers: Synthesis, Macromolecular architecture and scaffold design
2011 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Electrically conducting polymers induce specific cellular responses at the molecular level. One of the crucial limitations of the use of conducting polymers in tissue engineering is their inability to degrade. The incorporation of conductivity into degradable polymers to obtain materials that are both electroactive and degradable is therefore highly anticipated. Architecture plays an important role in the performance of polymers. To be able to achieve the optimal mechanical, degradation, thermal and biological properties for a particular biomedical application, it is desirable to promote architectural diversity.

 In the first part, by combining the electroactivity of conducting polymers and the degradability of aliphatic polyesters, we have designed and synthesized a series of linear, star-shaped, hyperbranched, and crosslinked degradable and electrically conducting polymers and hydrogels based on polylactide (PLA), polycaprolactone (PCL), and aniline oligomers such as aniline trimer, aniline tetramer, and aniline pentamer. The polymers and hydrogels obtained have good electroactivity, as indicated by their ultraviolet spectra and by cyclic voltammetry. The conductivities of the polymers and hydrogels are tuned by the content of the aniline oligomer and the macromolecular architecture. The hydrophilicity of the polymers was greatly increased after doping the aniline oligomer with acid, which overcomes the hydrophobicity of the PLA and PCL. Thermogravimetric analysis and differential scanning calorimetry studies show that these copolymers and hydrogels have good thermal properties compared to PLA and PCL. The swelling ratios of these hydrogels covered a wide range and were controlled by the degree of crosslinking, the oligoaniline content, and the pH of the surrounding solution.

 In the next part, methods for the facile synthesis of degradable conducting polymers and hydrogels were presented to avoid the multi-step reaction used in the earlier work. We developed a one-pot reaction for the synthesis of degradable conducting polysaccharide hydrogels based on chitosan and aniline tetramer. These hydrogels can form free-standing and flexible conducting films. This overcomes the drawback of polyaniline which could not be easily fabricated into a thin film in common organic solvents. We also presented a universal two-step approach to create degradable conductive diblock or triblock copolymers based on a polyester and aniline tetramer or aniline pentamer by a combination of ring opening polymerization and post-functionalization via an oxidative coupling reaction. The self-assembly behavior of the triblock copolymer consisting of a middle aniline pentamer segment and two bilateral polycaprolactone segments in chloroform as a selective solvent (selective for PCL segment) were also investigated by transmission electron microscopy and dynamic light scattering. The size of the nanoparticles from the assembly of the triblock copolymers depends on the molecular weight of the copolymer and on the aniline pentamer state.

 In the last part, electroactive degradable non-toxic porous tubular scaffolds were fabricated from a polymer blend of hyperbranched degradable conductive copolymer and PCL by a modified solution-casting/particle-leaching technique. The porous structure of the tubular scaffolds was investigated by scanning electron microscope and microcomputed tomography. The hydrophilicity of the blend films was greatly improved by doping with (±)-10-camphorsulfonic acid. The conductivity of the films was tuned by adjusting the ratio of hyperbranched degradable conducting copolymer to PCL. The cytotoxicity test with HaCaT keratinocytes indicated that the materials were non-toxic.

 These degradable electroactive copolymers and hydrogels with different architectures and properties have a great potential for meeting the requirements of biomedical application.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2011. 87 p.
Series
Trita-CHE-Report, ISSN 1654-1081 ; 2011:55
Keyword
Poly(lactide), poly(ε-caprolactone), ring-opening polymerization, carboxyl-capped aniline trimer, carboxyl-capped aniline pentamer, phenyl amino-capped aniline tetramer, coupling reaction, DCC/DMAP system, degradability, electroactivity, conductivity, macromolecular architecture, chitosan, hydrogel, block copolymer, functionalization, oxidative coupling reaction, self-assembly, toxicity, tubular porous scaffold, neural tissue engineering.
National Category
Engineering and Technology
Identifiers
urn:nbn:se:kth:diva-48171 (URN)978-91-7501-136-3 (ISBN)
Public defence
2011-12-07, F3, Lindstedsvägen 26, KTH,, Stockholm, 10:00 (English)
Opponent
Supervisors
Note
QC 20111123Available from: 2011-11-23 Created: 2011-11-16 Last updated: 2011-11-23Bibliographically approved

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