Surface modification of polymers for the preparation of high-performance polymer-apatite hybrids by a process mimicking biomineralization

2006 Fiscal Year Final Research Report Summary

• Project/Area Number: 17550191
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Polymer/Textile materials
• Research Institution: Kyoto Institute of Technology
• Principal Investigator: MINODA Masahiko Kyoto Institute of Technology, Graduate School of Science and Technology, Associate Professor, 工芸科学研究科, 助教授 (30229786)
• Project Period (FY): 2005 – 2006
• Keywords: biomineralization / bone-like apatite / polymer-apatite hybrids / calcium silicate gel / titania gel / sol-gel reaction / silane coupling reaction / organic-inorganic boundary structure

Research Abstract

This study focuses on the preparation of a new class of chitin-apatite hybrids by a process mimicking biomineralization. Hereafter, this process is refered to as a biomimitic process. To this end, commercial chitin-based porous gel particles were treated with a calcium silicate solution to modify their surfaces with Si-OH functions and calcium ions, and then soaked in simulated body fluid (SBF). Calcium silicate layer-coated chitin particles were obtained by sol-gel reaction with tetraethoxysilane (TEOS). It was found that the bonelike apatite forms on the surfaces of TEOS-modified particles after soaking in SBF at 36.5℃ for 3d. However, particles with wrinkled surface structure and flaking of the coated layers were observed. To prepare hybrids with improved surface structure, the particles were coated with an alternative calcium silicate solution containing both TEOS and methyltriethoxysilane (MTEOS), then soaked in SBF. The TEOS/MTEOS-based process resulted in the formation of apatit e-coated chitin particles with relatively uniform surface structure.
This study also deals with the praeparation of polymer-apatite hybrids by a biomimetic process employing TiO2-based modification. PET plates and PP films were treated with a Ti(OiPr)4 (TIPT)-based solution to modify their surfaces with a titania gel, immersed in boiling water for 3h to form crystalline titania layer with anatase structure, and then soaked in SBF for 3d. A uniform apatite layer formed on the surfaces of the substrates. Next, the surfaces of PET substrates were slightly hydrolyzed under basic condition, and then modified with a silane coupling agent, 3-isocyanatopropyltriethoxysilane (IPTS). The IPTS-modified PET plates were treated with a titania solution, boiling water, and then soaked in SBF. SEM observation clearly shows the formation of a uniform apatite layer on the substrates. Peeling test using an adhesive tape revealed that the hybrid of IPTS-modified PET plates exhibited increased organic-inorganic boundary strength compared to that of untreated PET plates.