A simple and effective method of fabricating scaffolds with open pore structures was successfully used on several copolymers. The method, which is straightforward and fast, was developed to overcome problems such as low pore interconnectivity and to achieve thick three-dimensional scaffolds. Copolymers are of particular interest because it is possible to tune their mechanical and degradable properties, and in this work, copolymers of l-lactide (LLA) and trimethylene carbonate (TMC) were synthesized through ring-opening polymerization. The copolymers formed had molecular weights ranging from close to 60000 g/mol to over 300000 g/mol and they were composed of 12−55 molar percentages of TMC and 88−45 molar percentages of LLA. The synthesized copolymers were evaluated as scaffold materials using a combined phase separation and particulate leaching technique, in which sugar templates were used as the leachable porosifiers. Differences in molecular weights, molar compositions, and degrees of crystallinity were ...
Star-shaped homo- and copolymers were synthesized in a controlled fashion using two different initiating systems. Homopolymers of E-caprolactone, L-lactide, and 1,5-dioxepan-2-one were firstly poly ...
This article presents the successful large-batch synthesis of a resorbable polymer with a minimal amount of residual tin. Ring-opening polymerization of e-caprolactone was performed in toluene, wit ...
Using zirconium(IV) acetylacetonate as an initiator of lactide/trimethylene carbonate copolymerization allowed us to obtain high-molecular-weight copolymers with high efficiency. The reactivity ratios of the comonomers were 13.0 for lactide and 0.53 for trimethylene carbonate. Despite the large differences between the values of the reactivity ratios, copolymers with randomized chain structures were obtained. This phenomenon occurred as a result of an intensive intermolecular transesterification ...
The new combinations of monomers presented in this work were evaluated in order to create an elastic material for potential application in soft tissue engineering. Thermoplastic elastomers (TPE) of trimethylene carbonate (TMC) with l-lactide (LLA) and 1,5-dioxepan-2-one (DXO) have been synthesized using a cyclic five-membered tin alkoxide initiator. The block copolymers were designed in such a way that poly(trimethylene carbonate−co-1,5-dioxepan-2-one) formed an amorphous middle block and the po...
Porous scaffolds of 1,5-dioxepan-2-one (DXO), L-lactide (LLA), and epsilon-caprolactone (CL) were prepared by a solvent casting, salt particulate leaching technique in which the composites were det ...
Following our continued interest in the production of bioerodible and biodegradable functional polymers for biomedical applications, we synthesized and characterized new unsaturated polyesters. The presence of functional groups in the polymer backbone provided sites for chemical modification, and through a variation in the structure, the physical properties, such as the hydrophilicity and solubility, could be affected. With 1,1-di-n-butyl-stanna-2,7-dioxacyclo-4-heptene as the initiator in the r...
Last. Jan Feijen(UT: University of Twente)H-Index: 117
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Three-dimensional degradable porous polymeric structures with high porosities (93-98%) and well-interconnected pore networks have been prepared by freeze-drying polymer solutions in the presence of a leachable template followed by leaching of the template. Templates of the pore network were prepared by fusing sugar or salt particles to form a well-connected structure. The interstices of the template were then filled with a polymer solution (5-15% w/v) in 1,4-dioxane, followed by freeze-drying of...
Tissue engineering offers a promising new approach to repair bone defects. Its practical realisation is connected with the development of suitable scaffold materials. In the present work, functionalized oligolactides have been prepared and used as macromers for the scaffold fabrication. The developed fabrication process leads to highly porous scaffolds, available in various shapes and sizes, with an open interconnective pore structure and porosities up to 90 %. Degradable or even osteoconductive...
New resorbable and elastomeric ABA tri- and multiblock copolymers have been successfully synthesized by combining ring-opening polymerization with ring-opening polycondensation. Five different poly(l-lactide-b-1,5-dioxepan-2-one-b-l-lactide) triblock copolymers and one new poly(l-lactide-b-1,5-dioxepan-2-one) multiblock copolymer have been synthesized. The triblock copolymers were obtained by ring-opening polymerization of 1,5-dioxepan-2-one (DXO) and l-lactide (LLA) with a cyclic tin initiator....
Last. Chee-Yoon Yue(NTU: Nanyang Technological University)H-Index: 23
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For tissue regeneration and tissue engineering applications, a number of bioactive and biodegradable composites, either porous or non-porous, were fabricated. The newly developed materials included tricalcium phosphate reinforced polyhydroxybutyrate and its copolymer, poorly crystallized hydroxyapatite reinforced chitin, and plasma sprayed hydroxyapatite reinforced poly(L-lactic acid). It was shown that these new materials could be successfully produced using the manufacturing techniques adopted...
Abstract Additive manufacturing is suitable for producing complex geometries; however, variation in thermo-mechanical properties is observed during one batch cycle when degradable aliphatic polyesters are used in melt extrusion-based methods. This is one important reason for why additive manufacturing has not yet been fully utilised to produce degradable medical implants. Herein, the internal variation has been minimised during one batch cycle by assessing the effect of different processing para...
Last. Piotr Ulanski(TUL: Lodz University of Technology)H-Index: 27
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Abstract The main objective of the work was to elaborate a methodology of manufacturing tubular guide with an internal scaffold of polysaccharide hydrogel towards potential application for supporting peripheral nerve regeneration. Carboxymethylchitosan (CMSC), a derivative of chitosan and a prospective material in the medical field, was examined with respect to degradation and crosslinking processes and eventually converted into a hydrogel through radiation-induced crosslinking. Physical-chemica...
: Polyester-based scaffolds covalently functionalized with arginine-glycine-aspartic acid-cysteine (RGDC) peptide sequences support the proliferation and osteogenic differentiation of stem cells. The aim is to create an optimized 3D niche to sustain human bone marrow stem cell (hBMSC) viability and osteogenic commitment, without reliance on differentiation media. Scaffolds consisting of poly(lactide-co-trimethylene carbonate), poly(LA-co-TMC), and functionalized poly(lactide) copolymers with pen...
Abstract We have succeeded to modulated the degradation rate of poly( l -lactide) (PLLA) melt-spun multifilament fibers to extend the service lifetime and increase the resorption rate by using random copolymers of l -lactide and trimethylene carbonate (TMC). The presence of TMC units enabled an overall longer service lifetime but faster degradation kinetics than PLLA. By increasing the amount of TMC up to 18 mol%, multifilament fibers characterized by a homogenous degradation profile could be ac...
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 sy...
#1Xiang Li(CAS: Chinese Academy of Sciences)H-Index: 6
#2Chenyang Hu(CAS: Chinese Academy of Sciences)H-Index: 7
Last. Xuesi Chen(CAS: Chinese Academy of Sciences)H-Index: 5
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Poly(propylene carbonate) (PPC) and polylactide (PLA), two major types of biodegradable polymers, are produced by the cooperative ring-opening polymerization (coROP) of propylene oxide and CO2 and by the ring-opening polymerization (ROP) of lactide. Because of the incompatibility between coROP and ROP, only simple copolymers of PPC and PLA with up to three blocks have been synthesized. A hybrid of these two polymers would produce a new family of polymers. The new polymers would be regarded as pr...
#1Mark Abubekerov(UCLA: University of California, Los Angeles)H-Index: 5
#2Junnian Wei(UCLA: University of California, Los Angeles)H-Index: 17
Last. Paula L. Diaconescu(UCLA: University of California, Los Angeles)H-Index: 35
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Poly(L-lactide) (PLA) is a bioderived and biodegradable polymer that has limited applications due to its hard and brittle nature. Incorporation of 1,3-trimethylene carbonate into PLA, in a block copolymer fashion, improves the mechanical properties, while retaining the biodegradability of the polymer, and broadens its range of applications. However, the preparation of 1,3-trimethylene carbonate (TMC)/L-lactide (LA) copolymers beyond diblock and triblock structures has not been reported, with exp...
#2Ioannis Tsivintzelis(A.U.Th.: Aristotle University of Thessaloniki)H-Index: 23
Last. Costas Panayiotou(A.U.Th.: Aristotle University of Thessaloniki)H-Index: 65
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In this work, porous structures of poly(L-lactic acid)-co-(tri-methylene-carbonate) (PLLA-co-TMC) were successfully fabricated using two experimental methods, that is, using supercritical CO2 as antisolvent and as foaming agent through the pressure induced phase separation technique. Considering the phase inversion method, the effect of the initial polymer concentration of the solution, pressure, and temperature on the morphology of the final porous structure (pore size, porosity, and cell densi...
This chapter reviews hydrolytic degradation and biodegradation of poly(lactic acid) (PLA). Hydrolytic degradation, which induces morphological and compositional changes, is considered the most important step in biodegradation. The main factors influencing hydrolytic degradation (temperature, pH, sample morphology, and molecular weight) are considered and analyzed. An overview of biodegradation under composting conditions is also given. The chapter also analyses the possibilities of modulating de...