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Photoreactive Functionalization of Poly(ethylene terephthalate) Track‐Etched Pore Surfaces with “Smart” Polymer Systems
Author(s) -
Geismann Christian,
Ulbricht Mathias
Publication year - 2005
Publication title -
macromolecular chemistry and physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.57
H-Index - 112
eISSN - 1521-3935
pISSN - 1022-1352
DOI - 10.1002/macp.200400374
Subject(s) - photoinitiator , surface modification , polymer chemistry , membrane , polymer , materials science , chemical engineering , photografting , grafting , chemistry , monomer , composite material , biochemistry , engineering
Abstract Summary: Poly(ethylene terephthalate) (PET) track‐etched membranes with a pore diameter of ca. 700 nm, optionally surface‐functionalized to create a “carboxyl” or “amino” surface, were used for heterogeneous graft copolymerizations. Grafted poly(acrylic acid) acted as a pH responsive, “smart” polymer. To evaluate the surface‐specific initiation of graft copolymerizations unmodified and primary functionalized membranes were systematically combined with three differently charged benzophenone derivatives as photoinitiators, which were adsorbed on the PET surface prior to the reaction. The functionalized membranes thus obtained were characterized for chemical structure and permeability as a function of pH. The pore structure with a narrow size distribution and the resulting high sensitivity of the membrane permeability to the grafting functionalizations made the track‐etched PET membranes a very useful tool for analyzing structure and function of responsive grafted polymer layers. The primary functionalization of the base polymer with a molecular layer of a multifunctional alkylamine (“amino” surface) enhanced the efficiency of the subsequent graft copolymerization via photoinitiated hydrogen abstraction considerably because a high density of well accessible reactive groups had been introduced. The preadsorption of the photoinitiator on the base polymer surface was significantly improved by ionic interactions between the respective functional groups of the surface and the photoinitiator. Such a photoinitiator preadsorption, especially when combined with a reactive layer from the primary functionalization, enabled a very efficient and surface selective functionalization because a better control of grafting density and a reduction of photoinitiated side reactions along with a more efficient use of the photoinitiator were possible.Water permeabilities (pH 2 and pH 7) of unmodified and functionalized PET membranes for identification of optimal synthesis and evaluation conditions.