TUNED MECHANICAL PROPERTIES ACHIEVED BY VARYING POLYMER STRUCTURE — KNOWLEDGE THAT GENERATES NEW MATERIALS FOR TISSUE ENGINEERING

By changing both the monomer composition and the polymer structure, we have varied the mechanical properties of resorbable polymers. The polymers were synthesized by ring-opening polymerization using L-lactide （LLA）, ε-caprolactone （εCL）, trimethylene carbonate （TMC） and 1,5-dioxepan-2-one （DXO） as monomers. Well-defined triblock copolymers, microblock copolymers and networks have been evaluated, and comparisons between them show that it is possible to tune the mechanical properties. Triblock copolymers with an amorphous middle block of poly（1,5-dioxepan-2- one） （PDXO） and semi-crystalline end-blocks of poly（ε-caprolactone） （PCL） were stronger and had a higher strain at break than triblock copolymers with poly（L-lactide） （PLLA） as end-blocks. Polymers with both DXO and TMC in the amorphous middle-block and PLLA as end-blocks showed a lower stress at break, but the material gained elasticity, a property which is very valuable in tissue engineering. Mechanical properties of networks, synthesized by a novel method, containing PDXO and PCL are also presented. Although it is difficult to compare them with the uncross-linked polymers, this is an additional way to modify and widen the properties.

TUNED MECHANICAL PROPERTIES ACHIEVED BY VARYING POLYMER STRUCTURE——KNOWLEDGE THAT GENERATES NEW MATERIALS FOR TISSUE ENGINEERING

By changing both the monomer composition and the polymer structure,we have varied the mechanical properties of resorbable polymers.The polymers were synthesized by ring-opening polymerization using L-lactide(LLA),ε-caprolactone(εCL),trimethylene carbonate(TMC)and 1,5-dioxepan-2-one(DXO)as monomers.Well-defined triblock copolymers,microblock copolymers and networks have been evaluated,and comparisons between them show that it is possible to tune the mechanical properties.Triblock copolymers with an amorphous middle block of poly(1,5-dioxepan-2-one)(PDXO) and semi-crystalline end-blocks of poly(ε-caprolactone)(PCL)were stronger and had a higher strain at break than triblock copolymers with poly(L-lactide)(PLLA)as end-blocks.Polymers with both DXO and TMC in the amorphous middle-block and PLLA as end-blocks showed a lower stress at break,but the material gained elasticity,a property which is very valuable in tissue engineering.Mechanical properties of networks,synthesized by a novel method,containing PDXO and PCL are also presented.Although it is difficult to compare them with the uncross-linked polymers,this is an additional way to modify and widen the properties.