| 1. |
- Guo, Baolin, 1981-
(författare)
-
Synthesis, characterization and molecular architecture of electroactive and degradable polymers
- 2010
-
Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- 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.
|
|
| 2. |
- Zhu Ryberg, Yingzhi
(författare)
-
Wood Hydrolysate for Renewable Products
- 2011
-
Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Renewable biomass has been used by mankind for a long time for different purposes, from simply food to industrial products. Among a large family of polysaccharides, hemicellulose is non-edible but has shown a potential in many industrial fields such as medicine, agriculture and packaging. However, a complicated process is usually required to extract highly purified hemicellulose for further applications, which makes it not practical and economical for real industrial applications.This thesis presents the utilization of a wood hydrolysate which was simply upgraded and recovered instead of being highly purified from the liquid by-product in the pulp industry. This softwood hydrolysate is rich in hemicellulose, O-acetyl galactoglucomannan (AcGGM), and also contains some lignin.Films and coatings were produced based on this wood hydrolysate by blending with two other polysaccharide co-components, carboxymethyl cellulose (CMC) and chitosan. Different recipes with a variety of concentrations and compositions were prepared. For comparison, highly purified AcGGM-based films and coatings were also produced.Mechanical properties and water vapor and oxygen barrier properties of the films and coatings were investigated. It was found that as a co-component, chitosan improved the mechanical properties best, and CMC gave better oxygen barrier properties at both 50% and 80% relative humidity. The wood-hydrolysate-based films gave much lower oxygen permeability (OP) values than AcGGM-based films.In order to reveal why the less purified wood hydrolysate gave a better oxygen barrier, both theoretical and experimental studies were carried out. A group calculation based on Hansen’s Solubility parameter theory (HSP) showed that there were strong interactions between lignin and AcGGM in the wood hydrolysate and also that CMC was more compatible with wood hydrolysate/AcGGM than chitosan. These led to an affinity between components and gave a more compact molecular structure, and thus a smaller free volume in the matrix. This interpretation was in agreement with the Positron annihilation lifetime spectra (PALS) data, which showed that wood-hydrolysate-based films had a smaller free volume (hole size) and narrower distribution than AcGGM-based films. It also showed that CMC-co-component films had smaller hole radii in the matrix than chitosan-co-component films. Thermal properties and FTIR also shed light on the influence and nature of these interactions.
|
|
| 3. |
- Adamus, Grazyna, et al.
(författare)
-
MALDI-TOF MS Reveals the Molecular Level Structures of Different Hydrophilic-Hydrophobic Polyether-esters
- 2009
-
Ingår i: Biomacromolecules. - : American Chemical Society (ACS). - 1525-7797 .- 1526-4602. ; 10:6, s. 1540-1546
-
Tidskriftsartikel (refereegranskat)abstract
- Multi- and triblock copolymers based on 1,5-dioxepan-2-one/epsilon-caprolactone (DXO/CL) were investigated by MALDI-TOF MS to determine the influence of copolymer composition and architecture on the molecular structures at the individual chain level. The copolymer compositions, average block lengths, and molecular weights were determined by H-1 and C-13 NMR and by SEC, respectively. The structures of polyether-ester oligomers (linear, cyclic) as well as the chemical structures of their end groups were established on the basis of their MALDI-TOF mass spectra. The mass spectrum of PDXO homopolymer was relatively simple, however, complex mass spectra were obtained in the case of multi- and triblock copolymers and the mass spectra clearly discerned the molecular level effect of copolymer composition and copolymer type.
|
|
| 4. |
- Agfors, Gunnar, et al.
(författare)
-
KEMI : den gränslösa vetenskapen
- 2011
-
Bok (populärvet., debatt m.m.)abstract
- Kemi – handlar inte det bara om farliga ämnen och onödiga tillsatser? Det är kanske bildenmånga har av kemi, men faktum är att utan kemi skulle vi inte ha det höga välstånd vi har i dag.Tack vare kemisk kunskap har vi tillgång till läkemedel som botar sjukdomar och lindrar smärta– med hjälp av syntetiska antibiotika kan infektionssjukdomar som tidigare var dödliga botas,magsår kan behandlas utan dyra och plågsamma operationer och många cancerformer kanframgångsrikt behandlas med syntetiska preparat. Konstgödsel och medel som hindrar skadeinsektergör att skördar kan ökas och svälten i världen därigenom begränsas. Tack vare kemin harvi även tillgång till alla de material vi behöver för att tillverka allt från kläder, rengöringsprodukteroch kosmetika till bilar, TV-apparater och reservdelar till kroppen. Det är genom kemisk syntes vikan framställa dessa och alla de övriga produkter vi behöver för vårt dagliga liv och det är keminsom visar vägen till hållbar produktion som utnyttjar förnybara råvaror och ger minimala mängderavfall. Kemisk kunskap är också oumbärlig för utveckling av nanoteknik och medicinskdiagnostik och andra till kemin angränsande områden. Kemin bidrar alltså till att finna lösningartill många av de komplexa globala problem vi står inför: hälsa, klimat, brist på råvaror, utnyttjandetav nya energikällor och tillgång till livsmedel för att föda jordens ökande befolkning. DET ÄR OM ALLT DETTA DEN HÄR BOKEN HANDLAR.
|
|
| 5. |
|
|
| 6. |
|
|
| 7. |
- Albertsson, Ann-Christine
(författare)
-
Celebrating 20 years of Biomacromolecules!
- 2019
-
Ingår i: Biomacromolecules. - : American Chemical Society (ACS). - 1525-7797 .- 1526-4602. ; 20:2, s. 767-768
-
Tidskriftsartikel (refereegranskat)
|
|
| 8. |
- Albertsson, Ann-Christine
(författare)
-
CELL 104-Renewable and/or degradable polymers
- 2007
-
Ingår i: Abstracts of Papers of the American Chemical Society. - : AMER CHEMICAL SOC. - 0065-7727. ; 233, s. 796-796
-
Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
|
|
| 9. |
|
|
| 10. |
- Albertsson, Ann-Christine, et al.
(författare)
-
Controlled ring-opening polymerization of lactones and lactides
- 2000
-
Ingår i: Macromolecular Symposia. - 1022-1360 .- 1521-3900. ; 157, s. 39-46
-
Tidskriftsartikel (refereegranskat)abstract
- 1,5-dioxepan-2-one (DXO) is presented as a versatile component in biodegradable polymers for biomedical applications. Copolymerization of DXO and L-lactide yielded a semi-crystalline, yet flexible, material where the extent of crystallinity and erosion characteristics were controlled by an appropriate choice of copolymer composition. Crosslinked PDXO was polymerized as a novel biodegradable elastomer. The degradation behavior of these materials were explored in vitro. Microspheres from poly(DXO-co-L-LA) were prepared and shown to be promising candidates for controlled release. The polymer composition and drug solubility provided effective means of controlling the drug delivery pattern.
|
|
