Objective
Direct fluorination (i.e. treatment with gaseous fluorine or fluorine-containing mixtures) is of significant importance for the surface modification of polymers. For example, this can lead to an enhancement of gas separation, barrier and adhesion properties of polymers. However, a fundamental understanding of the direct fluorination process remains scanty. Hence the main goal of the project is to develop the chemical-physical picture of the direct fluorination of glassy polymers and graft polymerization onto these fluorinated surfaces. The following glassy polymers will be studied:
polyvinyltrimethylsilane (PVTMS) and poly[1-(trimethylsilyl) propyne]
(PTMSP) and
poly(2,6-dimethyl-1,4-phenylene oxide) (poly(phenylene oxide) (PPO)) and
polyimide (PI). The research activities will be as follows:
preparation of starting polymeric samples: flat films and membranes (flat
and hollow fiber shape);
the modification of polymeric samples by direct fluorination and graft
polymerization;
the influence of treatment conditions (fluorination duration, composition
and partial pressures of the components of fluorinating mixture, nature of
the grafted monomer) will be investigated;
investigation of the physicochemical nature of fluorinated polymers by X-ray
photoelectron spectroscopy, time-of-flight secondary ion mass spectrometry,
ultraviolet photoelectron spectroscopy, infrared spectroscopy, Raman
microscopy, and atomic force microscopy;
study of the dependence of the surface energy on treatment duration and on
composition and partial pressures of the components of the fluorinating
mixture;
investigation of the kinetics of the fluorinated layer formation and
evaluation of the thickness of the reaction zone between fluorinated and
untreated polymer layers;
measurement of the absorption spectra in the near UV and visible, specific
gravity and the dependence of the refraction index of PPO on wavenumber;
monitoring and identification of the radicals which are chain carriers and
development of the scheme of the elementary chain chemical reaction
pathways;
study of the kinetics of graft polymerization of monomers onto fluorinated
and oxyfluorinated polymers, and the resultant physico-chemical properties
of such grafted layers;
investigation of the influence of the direct fluorination on the
electrochemical properties of polymers when in contact with aprotic solvent;
investigation of the influence of
-(a) direct fluorination and
-(b) fluorination accompanied with graft polymerization on the gas
-transport properties (diffusivity, permeability, gas separation factor)
-of polymer membranes;
development of a theoretical model for the direct fluorination of polymers. Overall, a detailed mollar level understanding of the surface fluorination of glassy polymers is to be undertaken, which will then be applied to graft polymerization, gas separation membranes, and electrochemical behaviour.
Topic(s)
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Data not availableFunding Scheme
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DURHAM
United Kingdom