Dye-doped PDLC

Figure 11.24 Schematic diagram showing how the dichroic dye doped PDLC works (a) absorbing state, (b) transparent state.

Morphological Evolution of Dye Doped PDLC Composite Films... 

The addition of dichroic azo red dye in NOA65/E7 was found to have a considerable influence on the UV-curing polymerization (photo-polymerization). The method of preparation of dye doped PDLC (DPDLC) is described elsewhere (Deshmukh et al. 2012a Jain and Deshmukh 2014). The dye in polymer-LC mixture impedes/slowdowns the polymerization process, with almost no appearance of separation of LC-rich and polymer-rich regions for a comparatively long period of photo-polymerization. The 0.5 wt% dye-doped PDLC mixture showed start of phase separation of LC material at around 60 s, as shown in Fig. 7.2. The slower rate of photo-polymerization facilitates the growth of LC droplets by diffusion, coalescence process as the increase in polymer viscosity is not much. 

An analysis of above equation indicates that is predominantly a function of the applied voltage, where mostly depends on the LC domain size and shape and the anchoring energy with polymer wall (Kalkar et al. 2008). The variation in rise time and decay time studied for undoped NOA 65/LC E7 and dye doped PDLC composite film is given in Table 7.2. 

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