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Interfacial-gel copolymerization

Several approaches have been developed to prepare GRIN polymer fibers in our laboratories, e.g., initiator diffusion technique (70), interfacial-gel copolymerization (77), and extrusion technique (12,13). Our previous study successfully used a closed extrusion process to prepare GRIN polymer fibers (72,75). This new process has also overcomed several drawbacks in conventional extrusion processes, e.g., poor reproducibility and low production rate. The refractive index profiles of the GRIN polymer fibers prepared by the new process are affected by the following two factors (1) the formulation of the reactant mixtures, e.g., different types of monomer combination and variation of host polymers and (2)... [Pg.71]

The initial methods to fabricate GI preforms took advantage of the difference in monomer reactivity ratios in copolymerization reactions. These methods are of two types photo-copolymerization [4-6] and interfacial-gel copolymerization [7, 8]. [Pg.82]

Table 5.1 Categories of possible monomers for photo-copolymerization and interfacial-gel copolymerization processes. Table 5.1 Categories of possible monomers for photo-copolymerization and interfacial-gel copolymerization processes.
As the main part of the GI-POFs is composed of PMMA, the loss spectrum is nearly the same as that of SI-POF with PMMA core. The attenuation loss of GI-POF with the gel-copolymerization technique at 652 nm is 134 dB/kra Koike s group, Keio University, has used an interfacial-gel-polymerization technique where bro-mobenzene or other chemicals are used as unreactive components instead of vinyl phenyl acetate or vinyl benzoate in the interfacial-gel-copolymerization method. An attenuation loss of 90 dB/km at 572 nm was obtained. MMA-dg was also used as a monomer instead of MMA, and the deuterated polymer core GI-POF was successfully fabricated. Fluorinated acrylate monomer was also used to fabricate moisture-resistant GI-POF. Attenuation losses of 113 and 155 dB/km at 780 nm wavelength were obtained for deuterated and fluorinated POFs, respectively. These POFs are Oj pected to serve as the signal transmission medium with high information capacities in local area network systems. However, this GI-POF has not been commercially available so far because of the fabrication difficulty of the technique in a mass production level with reasonable attenuation loss and fabrication cost. [Pg.221]

G1 preforms can also be fabricated by an interfacial-gel polymerization technique. The principle is basically the same as that of the photo-copolymerization method discussed above, except for the mechanism that forms the initial gel phase. In this method, the core solution (the monomer) is placed in a polymer tube rather than in a glass tube. The gel phase in the photo-copolymerization method is referred to as a prepolymer with a conversion of less than 100%, whereas in this method the gel phase comprises the polymer layer on the inner wall of the tube swollen by the core monomer. The reaction is carried out under UV irradiation or heating. [Pg.83]

In this method, nonreactive compounds are employed as the high-refractive-index component [11]. For example, MM A and bromobenzene (BB), which have higher refractive indices than PMMA, can be utilized as the monomer and the nonreactive compound, respectively. The fabrication procedure is the same as in the photo-copolymerization and interfacial-gel polymerization methods. However, the principle of formation the GI profile is different. In contrast to the previous methods that use the difference in the monomer reactivity ratios, in this method the difference in the molecular size is important. Because the molecular size of MM A is smaller than that of BB, MM A more easily diffuses into the gel phase. Thus, BB molecules are concentrated into the middle region to form the GI profile as the polymerization progresses. The mechanism is schematically described in Figure 5.11. [Pg.90]


See other pages where Interfacial-gel copolymerization is mentioned: [Pg.90]    [Pg.86]    [Pg.220]    [Pg.90]    [Pg.86]    [Pg.220]    [Pg.288]    [Pg.464]   
See also in sourсe #XX -- [ Pg.82 , Pg.85 , Pg.86 ]




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