Synthesis and barrier properties of poly(ε‐caprolactone)‐layered silicate nanocomposites
Tóm tắt
A new polymer‐ceramic nanocomposite has been synthesized consisting of well‐dispersed, two‐dimensional layers of an organically modified mica‐type silicate (MTS) within a degradable poly(ε‐caprolactone) matrix. A protonated amino acid derivative of MTS was used to promote delamination/dispersion of the host layers and initiate ring‐opening polymerization of ε‐caprolactone monomer, resulting in poly(ε‐caprolactone) chains that are ionically bound to the silicate layers. The polymer chains can be released from the silicate surface by a reverse ion‐exchange reaction and were shown to be spectroscopically similar to pure poly(ε‐caprolactone). Thick films of the polymer nanocomposite exhibit a significant reduction in water vapor permeability that shows a linear dependence on silicate content. The permeability of nanocomposite containing as low as 4.8% silicate by volume was reduced by nearly an order of magnitude compared to pure poly(ε‐caprolactone). © 1995 John Wiley & Sons, Inc.
Từ khóa
Tài liệu tham khảo
Pitt C. G., 1990, Biodegradable Polymers as Drug Delivery Systems, 71
Potts J. E., 1975, Soc. Plast. Eng. Tech. Pap., 21, 567
P. B.MessersmithandE. P.Giannelis Chem. Mater. to appear.
Yano K., 1991, Polym. Prepr., 32, 65
Saegusa T., 1993, Polym. Prepr., 34, 804
Grim R. E., 1968, Clay Mineralogy
Raque D. C., 1991, Plastics and Composites: Materials Properties, Part Performance, and Process Simulation, 149
Theng B. K. G., 1974, The Chemistry of Clay‐Organic Reactions, 133
Kemnetz S. J., 1989, J. Coatings Tech., 61, 47
P. B.MessersmithandE. P.Giannelis unpublished results.
Johns D. B., 1984, Ring‐Opening Polymerization, 461
Lundberg R. D., 1969, Ring‐Opening Polymerization, 247
Cullity B. D., 1978, Elements of X‐Ray Diffraction, 284
The apparent aspect ratio of approximately 70 is the result of curve‐fitting eq. (7) of Ref. 63 to the permeability data shown in Table IV. The use of this equation carries the assumption that permeability through the composite film is dominated by the tortuous diffusion paths created by overlapping silicate layers oriented parallel to the plane of the film.