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Orientation and In‐Situ Photopolymerization of a Diacetylene Monomer in Gel‐Processed Ultra‐High Molecular Weight Polyethylene: Films with Several Optical Security Features
Author(s) -
Uhm J.S.,
Giesa R.,
Schmidt H.W.
Publication year - 2002
Publication title -
advanced functional materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.069
H-Index - 322
eISSN - 1616-3028
pISSN - 1616-301X
DOI - 10.1002/1616-3028(20020618)12:6/7<441::aid-adfm441>3.0.co;2-1
Subject(s) - diacetylene , materials science , photopolymer , monomer , in situ , orientation (vector space) , polyethylene , composite material , polymer , organic chemistry , chemistry , geometry , mathematics
Highly transparent and oriented films of the diacetylene monomer, 5,7‐dodecadiyne‐1,12‐bis( n ‐butoxycarbonylmethylurethane) (4BCMU) in ultra‐high molecular weight polyethylene (UHMW PE) were prepared utilizing the gel‐processing technique with subsequent tensile drawing. After UV radiation the films yield highly absorbing and oriented poly‐4BMCU. The orientation of the polymerized 4BCMU form was investigated using polarized UV‐vis spectroscopy and wide‐angle X‐ray diffraction. Morphology studies showed that 4BCMU crystallized from the melt within the microchannels, with the monomer long axis perpendicular to the internal surfaces and therefore with the polymer axis parallel to the drawing direction. Thermal annealing and the transition to the red form of the films results in a five‐ to six‐fold increase in optical anisotropy. The described system combines several useful security features such as photopatterning, easily detectable optical anisotropy, and irreversible color change upon heating, which could be utilized in optical security devices.