Thermal and mechanical properties of nanocomposites based on a PLLA-b-PEO-b-PLLA triblock copolymer and nanohydroxyapatite

LıVIA M. D. LOIOLA; LAURA A. FASCE; LAURA C. E. DA SILVA; FRONTINI, PATRICIA; MARIA I. FELISBERTI

JOURNAL OF APPLIED POLYMER SCIENCE

JOHN WILEY & SONS INC

Lugar: New York; Año: 2016

0021-8995

Composites which combine biocompatible polymers and hydroxyapatite are unique materials with regards to theirmechanical properties and bioactivity in the development of temporary bone-fixation devices. Nanocomposites based on a biocompatibleand amphiphilic triblock copolymer of poly(L-lactide) (PLLA) and poly(ethylene oxide) (PEO) ?PLLA-b-PEO-b-PLLA? andneat (nHAp) or PEO-modified (nHAp@PEO) hydroxyapatite nanoparticles were prepared by dispersion in benzene solutions, followedby freeze-drying and injection moulding processes. The morphology of the copolymers of a PEO block dispersed throughout aPLLA matrix was not changed with addition of the nanofillers. The nHAp particles were spherical and, after modification, thenHAp@PEO nanoparticles were partially agglomerated. In the nanocomposites, these particles characteristics remained unchanged,and the nHAp particles and nHAp@PEO agglomerates were uniformly dispersed through the copolymer matrix. These particles actedas nucleating agents, with nHAp@PEO being more efficient. The incorporation of nHAp increased both the reduced elastic modulus(22%) and the indentation hardness (15%) in comparison to the copolymer matrix, as determined by nanoindentation tests,while nHAp@PEO addition resulted in lower increments of these mechanical parameters. The incorporation of untreated nHAp was,therefore, more beneficial with regards to the mechanical properties, since the amphiphilic PLLA-b-PEO-b-PLLA matrix was alreadyefficient for nHAp nanoparticles dispersion