title: High orientation of long chain branched poly (lactic acid) with enhanced blood compatibility and bionic structure.
abstract: Highly oriented poly (lactic acid) (PLA) with bionic microgrooves was fabricated through solid hot drawing technology for further improving the mechanical properties and blood biocompatibility of PLA. In order to enhance the melt strength and thus obtain high orientation degree, long chain branched PLA was prepared at first through a two-step ring-opening reaction during processing. Linear viscoelasticity combined with branch-on-branch model was used to predict probable compositions and chain topologies of the products, and it was found that the molecular weight of PLA increased and topological structures with star like chain with three arms and tree-like chain with two generations formed during reactive processing, and consequently draw ratio as high as1200% can be achieved during the subsequent hot stretching. With the increase of draw ratio, the tensile strength and orientation degree of PLA increased dramatically. Long chain branching and orientation could significantly enhance the blood compatibility of PLA by prolonging clotting time and decreasing platelet activation. Microgrooves can be observed on the surface of the oriented PLA which were similar to the intimal layer of blood vessel, and such bionic structure resulted from the formation of the oriented shish kebab-like crystals along the draw direction.
authors.affiliation: State Key Laboratory of Polymer Materials Engineering of China, Polymer Research Institute of Sichuan University, Chengdu, China.
authors.forename: Zhengqiu
authors.initials: Z
authors.lastname: Li
authors.affiliation: State Key Laboratory of Polymer Materials Engineering of China, Polymer Research Institute of Sichuan University, Chengdu, China.
authors.forename: Lin
authors.initials: L
authors.lastname: Ye
authors.affiliation: State Key Laboratory of Polymer Materials Engineering of China, Polymer Research Institute of Sichuan University, Chengdu, China.
authors.forename: Xiaowen
authors.initials: X
authors.lastname: Zhao
authors.affiliation: School of Engineering, Design and Technology, University of Bradford, Bradford, United Kingdom.
authors.forename: Phil
authors.initials: P
authors.lastname: Coates
authors.affiliation: School of Engineering, Design and Technology, University of Bradford, Bradford, United Kingdom.
authors.forename: Fin
authors.initials: F
authors.lastname: Caton-Rose
authors.affiliation: School of Engineering, Design and Technology, University of Bradford, Bradford, United Kingdom.
authors.forename: Michasel
authors.initials: M
authors.lastname: Martyn
mesh_terms: D001672:Biocompatible Materials / Q000737:chemistry* / Q000378:metabolism*; D001701:Bionics; D001777:Blood Coagulation / Q000187:drug effects; D006801:Humans; D008422:Materials Testing; D015539:Platelet Activation / Q000187:drug effects; D011091:Polyesters / Q000737:chemistry* / Q000378:metabolism*; D013718:Tensile Strength
chemical_list: D001672:Biocompatible Materials; D011091:Polyesters; C033616:poly(lactide)
keywords: bionic character; blood compatibility; long chain branching; mechanical properties; poly (lactic acid) (PLA)