| 1. |
- Asplund, Basse, et al.
(författare)
-
Effects of hydrolysis on a new biodegradable co-polymer
- 2006
-
Ingår i: Journal of Biomaterials Science. Polymer Edition. - : Informa UK Limited. - 0920-5063 .- 1568-5624. ; 17:6, s. 615-630
-
Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to examine the feasibility of using a new low-modulus biodegradable thermoplastic elastomer for in vivo application as a stent cover. The new polymer, a thermoplastic elastomer, consists of a three-armed co-polymer of poly(lactide)acid (PLLA), poly(trimethylene carbonate) (PTMC) and poly(caprolactone) (PCL). A degradation study was performed in a buffer solution at 37 degrees C for 4 and 6 weeks. The effect of degradation on mechanical properties was studied by stress-strain measurements and explained by using modulated DSC, GPC and mass measurements. A tapered block of PLLA and trimethylene carbonate connecting the crystalline outer part and the inner elastic part was highly susceptible to hydrolysis and caused rapid degradation and subsequent loss of mechanical properties. Random chain scission and homogenous hydrolysis resulted in a loss in mass and molecular weight. After 6 weeks of in vitro hydrolysis the molecular weight had decreased 54% and the elongation-at-break dropped from more than 300% to 90%. A medium free cell seeding study showed that endothelial cells adhered well to the polymeric material. An indicative animal study with the polymer acting as a stent cover showed very low levels of inflammation however, pronounced neointima thickening was observed which was probably due to the premature failure of the material.
|
|
| 2. |
- Fuoco, Tiziana, PhD, 1986-, et al.
(författare)
-
Poly(L-lactide) and Poly(L-lactide-co-trimethylene carbonate) Melt-Spun Fibers : Structure-Processing-Properties Relationship
- 2019
-
Ingår i: Biomacromolecules. - : AMER CHEMICAL SOC. - 1525-7797 .- 1526-4602. ; 20:3, s. 1346-1361
-
Tidskriftsartikel (refereegranskat)abstract
- l-Lactide/trimethylene carbonate copolymers have been produced as multifilament fibers by high-speed melt-spinning. The relationship existing between the composition, processing parameters and physical properties of the fibers has been disclosed by analyzing how the industrial process induced changes at the macromolecular level, i.e., the chain microstructure and crystallinity development. A poly(l-lactide) and three copolymers having trimethylene carbonate contents of 5, 10 and 18 mol % were synthesized with high molecular weight (M n ) up to 377 kDa and narrow dispersity. Their microstructure, crystallinity and thermal properties were dictated by the composition. The spinnability was then assessed for all the as-polymerized materials: four melt-spun multifilament fibers with increasing linear density were collected for each (co)polymer at a fixed take-up speed of 1800 m min -1 varying the mass throughput during the extrusion. A linear correlation resulted between the as-spun fiber properties and the linear density. The as-spun fibers could be further oriented, developing more crystallinity and improving their tensile properties by a second stage of hot-drawing. This ability was dependent on the composition and crystallinity achieved during the melt-spinning and the parameters selected for the hot-drawing, such as temperature, draw ratio and input speed. The crystalline structure evolved to a more stable form, and the degree of crystallinity increased from 0-52% to 25-66%. Values of tensile strength and Young's modulus up to 0.32-0.61 GPa and 4.9-8.4 GPa were respectively achieved.
|
|
| 3. |
- Pappalardo, Daniela, et al.
(författare)
-
Biocompatibility of Resorbable Polymers : A Historical Perspective and Framework for the Future
- 2019
-
Ingår i: Biomacromolecules. - : AMER CHEMICAL SOC. - 1525-7797 .- 1526-4602. ; 20:4, s. 1465-1477
-
Tidskriftsartikel (refereegranskat)abstract
- The history of resorbable polymers containing glycolide, lactide, e-caprolactone and trimethylene carbonate, with a special emphasis being placed on the time frame of the 1960s-1990s is described. Reviewing the history is valuable when looking into the future perspectives regarding how and where these monomers should be used. This story includes scientific evaluations indicating that these polymers are safe to use in medical devices, while the design of the medical device is not considered in this report. In particular, we present the data regarding the tissue response to implanted polymers, as well as the toxicity and pharmacokinetics of their degradation products. In the translation of these polymers from "the bench to the bedside," various challenges have been faced by surgeons, medical doctors, biologists, material engineers and polymer chemists. This Perspective highlights the visionary role played by the pioneers, addressing the problems that occurred on a case by case basis in translational medicine.
|
|
