Showing papers by "Ann-Christine Albertsson published in 2002"
TL;DR: The synthesis of aliphatic polyesters by polycondensation and ring-opening polymerization is reviewed in this paper, which includes homopolyesters, random, block, graft, star, and hyper-branched polyesters.
Abstract: The synthesis of aliphatic polyesters by polycondensation and ring-opening polymerization is reviewed. This includes homopolyesters, random, block, graft, star, and hyper-branched (co)polyesters. Recent progress in the synthesis of high molecular weight aliphatic polyesters is described. Specific properties of these polymers are also given. The biomedical and ecological applications of these biodegradable polymers show their technological importance and relevance.
532 citations
TL;DR: This review is concerned with degradable polymers for use in controlled drug delivery with emphasis on the preparation, applications, biocompatibility, and stability of microspheres from hydrolytically degradably polymers.
Abstract: Controlled drug delivery technology is concerned with the systematic release of a pharmaceutical agent to maintain a therapeutic level of the drug in the body for a sustained period of time. This may be achieved by incorporating the therapeutic agent into a degradable polymer vehicle, releasing the agent continuously as the matrix erodes. This review is concerned with degradable polymers for use in controlled drug delivery with emphasis on the preparation, applications, biocompatibility, and stability of microspheres from hydrolytically degradable polymers.
431 citations
TL;DR: In this paper, a review of ring-opening polymerization of lactones and lactides with different types of initiators and catalysts is presented, as well as their use in the synthesis of macromolecules with advanced architecture.
Abstract: This paper reviews ring-opening polymerization of lactones and lactides with different types of initiators and catalysts as well as their use in the synthesis of macromolecules with advanced architecture. The purpose of this paper is to review the latest developments within the coordination-insertion mechanism, and to describe the mechanisms and typical kinetic features. Cationic and anionic ring-opening polymerizations are mentioned only briefly.
368 citations
TL;DR: In this article, the authors present and discuss a number of aliphatic polyesters which show interesting applications as biomedical materials and degradable packages, starting with succinic acid and/or 1,3-propanediol.
Abstract: From the point of view of making novel polymers with inherent environment-favorable properties such as renewability and degradability, a series of interesting monomers are found in the metabolisms and cycles of nature. This review presents and discusses a number of aliphatic polyesters which show interesting applications as biomedical materials and degradable packages. Available from nature are amino acids, microbial metabolites from the conversion of glucose and other monosaccharides (e.g., acetic acid, acetone, 2,3-butanediol, butyric acid, isopropanol, propionic acid), lactic acid, ethanol and fatty acids. A series of biodegradable polymers with different properties and different potential industrial uses were made starting with succinic acid and/or 1,3-propanediol. There were two routes for making the polyester-based materials; the direct ring-opening polymerization of lactones (cyclic esters) synthesized from 1,3-propanediol, and the chain-extension of α,ω-dihydroxy-terminated oligomeric polyesters produced by thermal polycondensation of 1,3-propanediol and succinic acid (oligo(propylene succinate)s).
143 citations
TL;DR: The reaction between pentaerythritol ethoxylate compounds and dibutyltin oxide was developed as a route to synthesize two new spirocyclic tin initiators and the expected results were obtained.
119 citations
TL;DR: In this paper, a theoretical study of the ring-opening polymerization (ROP) mechanism of 1,5-dioxepan-2-one (DXO) and glycolide with Sn(II) and Al(III) alkoxide initiators (SnMe3MeO, SnMe2(MeO)2, and AlMe2MeO).
Abstract: A theoretical study is presented of the ring-opening polymerization (ROP) mechanism of 1,5-dioxepan-2-one (DXO) and glycolide with Sn(II) and Al(III) alkoxide initiators (SnMe3MeO, SnMe2(MeO)2, and AlMe2MeO). The B3LYP density functional method has been used to perform the quantum chemical calculations. A coordination−insertion mechanism is presented with two principal reaction steps. First, the alkoxide of the initiator performs a nucleophilic attack on the carbonyl carbon, and the carbonyl bond is broken. An intermediate is formed at this point, where the former carbonyl oxygen of the monomer is coordinated to tin via an alkoxide bond, while the carbonyl carbon assumes a sp3 bonding geometry. The second step involves the acyl−oxygen cleavage of the monomer. For all three initiators it was found that the transition state involving the breaking of the carbonyl double bond (TS1) represented the highest point on the potential energy surface for DXO. For glycolide, however, the transition state of the acyl−o...
84 citations
TL;DR: New resorbable and elastomeric ABA tri- and multiblock copolymers have been successfully synthesized by combining ring-opening polymerization with ring- opening polycondensation to retain very good mechanical properties throughout the in vitro degradation study.
84 citations
TL;DR: The barrier and mechanical properties of biodegradable melt-mixed polyesteramide/octadecylamine-treated montmorillonite clay (filler) have been studied as mentioned in this paper.
Abstract: The barrier and mechanical properties of biodegradable melt-mixed polyesteramide/octadecylamine-treated montmorillonite clay (filler) have been studied. Extruded films containing 5 and 13 wt% fille ...
75 citations
TL;DR: In this paper, gas chromatography-mass spectrometry (GC-MS) analysis showed that caprolactone, 6-hydroxyhexanoic acid, cyclic dimer and cyclic trimer were rapidly assimilated from the surface of polycaprolacton.
Abstract: Gas chromatography-mass spectrometry (GC-MS) analysis showed that caprolactone, 6-hydroxyhexanoic acid, cyclic dimer and cyclic trimer were rapidly assimilated from the surface of polycaprolactone ...
71 citations
TL;DR: Hydrosilylation grafting of PDMS is a promising method to obtain biomaterials with hydrolytically stable structures covalently bound to the surface.
47 citations
TL;DR: In this article, the oxidative thermal degradation of poloxamer 407, a poly(ethylene oxide-propylene oxide-ethylene dioxide) triblock copolymer, at 50 and 80 degreesC in air was studied by solid phase microextraction.
TL;DR: In this article, a star-shaped and photocrosslinked poly(1,5-dioxepan-2-one) (PDXO) has been synthesized through ring-opening polymerization initiated by SnOct2/pentaerythritol.
Abstract: New star-shaped and photocrosslinked poly(1,5-dioxepan-2-one) (PDXO) has been synthesized through ring-opening polymerization initiated by SnOct2/pentaerythritol. The star-shaped PDXO was end-functionalized by acrolyol chloride to form acrylate end groups. The end-functionalized PDXO was photocrosslinked initiated by 2,2-dimethoxy-2-phenylacetophenone. The gel content ranged from 80 to 99%, indicating a high degree of crosslinking. The thermal properties of the star-shaped PDXO and the photocrosslinked PDXO were analyzed by differential scanning calorimetry. The glass-transition temperature was determined to approximately −32 °C for the crosslinked PDXO. The viscosity numbers were determined for star-shaped PDXO, with reference to linear homologues. The star-shaped PDXO had lower viscosity numbers than the linear counterparts. The crosslinked PDXO showed a rather hydrophilic surface as compared with other resorbable polyesters. The advancing contact angle was 64 ± 2, and the receding angle was 57 ± 4. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 2049–2054, 2002
TL;DR: In this paper, a novel family of hydrosoluble biomaterials, called poly(N-vinyl-2-pyrrolidone) (PVP)-based graft copolymers, is proposed.
Abstract: This work is devoted to the design of a novel family of hydrosoluble biomaterials: poly(N-vinyl-2-pyrrolidone) (PVP)-based graft copolymers. A synthesis route has been elaborated in which ω-functionalized PVP is prepared via chain-transfer radical polymerization, end-group modified, and subsequently grafted onto a polyhydroxylated backbone, typically dextran or poly(vinyl alcohol). The resulting graft copolymer biomaterials are designed for use in various biomedical applications, particularly as materials with a stronger potential for plasma expansion than already existing products have. The graft copolymers are potentially degradable because the PVP grafts are connected to the polyol backbone via a hydrolytically labile carbonate or ester linkage. The degradation of the graft copolymers was performed in vitro over a period of 6 weeks. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 3652–3661, 2002
TL;DR: New high-molecular-weight hydrophobic/hydrophilic segmented copolymers of poly(ester-ether-carbonate) structure, containing poly(1,3-propylene succinate) (SP) and poly(ethylene glycol) (PEG) segmen... as discussed by the authors.
Abstract: New high-molecular-weight hydrophobic/hydrophilic segmented copolymers of poly(ester-ether-carbonate) structure, containing poly(1,3-propylene succinate) (SP) and poly(ethylene glycol) (PEG) segmen...
01 Jan 2002
TL;DR: The lifetime of a polymer is dependent not only on the weak links in the material but also on its surroundings as discussed by the authors, and degradation must be carefully monitored in order to evaluate the usefulness and service-life of polymers in different applications.
Abstract: The lifetime of a polymer is dependent not only on the weak links in the material but also on its surroundings. Degradation must be carefully monitored in order to evaluate the usefulness and service-life of polymers in different applications. As environmental concerns have increased, new demands are placed on the prediction of long-term properties of synthetic and natural polymers. When polymeric materials are exposed to a complex environment (e.g. outdoors) we may describe this as environmental degradation. Environmental degradation occurs due to a combination of factors of which photo-oxidation, thermo-oxidation, humidity, erosion by the weather and chemical action due to pollutants and micro-and macro-organisms are the most important. A combination of these may be cumulative, synergistic or antagonistic.
TL;DR: A new selective method for the quantification of organosilanol groups in silicone pre-elastomers is developed, based on derivatization of the silanol groups with a mixture of dimethylphenylchlorosilane and tetramethyldiphenylsilazane, which agreed well with the nonselective Karl Fischer titration for some short chain silanols.
TL;DR: This chapter discusses testing methods for testing biodegradability, patents on Environmentally Degradable Polyethylene, and photo-oxidation of polyethylene products.
Abstract: Introduction
Historical Outline
Methods for Testing Biodegradability
Plate Tests
Enzyme Assays
The Evolution of Gases
Soil Burial Tests
Composting
Anaerobic Biodegradation (Landfill)
Toxicity Testing
The Fate of Degradation Products and Polymer Fragments
Biodegradation of Polyethylene
Enhanced Environmentally Degradable Polyethylene
Modification of Polyethylene with Biodegradable Additives
Enhanced Photodegradable Polyethylene
Copolymerization with Biodegradable Monomers
Biodegradation of Enhanced Environmentally Degradable Polyethylene
Assimilation of Oxidized Polyethylene and its Degradation Products
Patents on Environmentally Degradable Polyethylene
Patents on Biodegradable Polyethylene
Patents on Photodegradable Polyethylene
Outlook and Perspectives
Keywords:
biodegradation;
polyethylene;
degradation products;
assimilation;
environmental degradation;
photodegradation;
photo-oxidation;
thermo-oxidation;
gas chromatography-mass spectroscopy;
abiotic degradation;
biotic degradation;
microorganism;
bacteria;
fungi;
enzyme;
FTIR;
starch;
pro-oxidant;
photo-initiator;
biodegradable additive
TL;DR: In this paper, a ternary XPS diagram is used to follow surface modification processes involving three elements, represented by a single data point on a plane instead of by two or three elemental ratios or percentages.
Abstract: The use of a ternary XPS diagram to follow surface modification processes involving three elements is described. The elemental composition is represented by a single data point on a plane instead of by two or three elemental ratios or percentages. Vectors are defined between the data points, and simple vector algebra is used to interpret the results. The extent of the surface change is determined by calculating the length of the vector from untreated to a treated composition point, and this leads to a value for the overall change in elemental composition. The direction of the vector indicates how the changes in the individual elemental percentages are related to each other, i.e. what elemental composition the surface is approaching. The ternary XPS diagram is demonstrated and compared with elemental percentages and ratios using XPS data from hydrogen microwave plasma-treated polydimethylsiloxane.