Synthesis and properties of azomethine polymers with bent-core mesogens

Figures & data

Scheme 1. Synthetic route to the azomethine polymers

Figure 1. DSC thermograms of the polymers (heating rate=5°C/min).

Table 1  Yields, thermal transition temperatures, and enthalpy changes of the polymers^a.

	Yield	Tk−k	Δ Hk−k	Tm	Δ Hm
Polymer	(wt%)	(^oC)	(J/g)	(°C)	(J/g)
3a	79.9	–	–	b	–
3b	88.1	195	4.6	229	13.9
3c	85.6	195	4.1	b	–

and stand for the temperature and the enthalpy change for the solid-to-solid transition.

^bThe polymer was thermally decomposed before melting.

Figure 2. Cross-polarizing optical micrographs of polymer 3a (magnification×250): (a) T=240°C; and (b) quenched sample of the melt.

Figure 3. Cross-polarizing optical micrographs of polymer 3b (magnification×250): (a) T=150°C; (b) T=200°C; (c) T=220°C; and (d) after shearing at 250°C.

Figure 4. Cross-polarizing optical micrographs of polymer 3c (magnification×250): (a) T=150°C; (b) T=200°C; (c) T=250°C; and (d) after shearing at 250°C.

Figure 5. XRD pattern of polymer 3a at room temperature.

Figure 6. XRD patterns of polymer 3b at different temperatures.

Figure 7. XRD patterns of polymer 3c at different temperatures: (a) heating to a moderate temperature so that thermal degradation would not occur and (b) heating to a high temperature so that the isotropic phase could be obtained.

Table 2  XRD data for the smectogenic polymers.

Polymer	L^a(Å)	q (nm^−1)	d (nm)
3b	35.5	2.06	3.05	32
3c	36.5	2.08	3.02	34

^aThe length of the molecule with the all-trans-conformation was calculated using the PCFF force field model of the material studio.

^bThe tilt angle was calculated by assuming that the bent angle was 60°, and there was no intercalation between the chains.

Figure 8. Schematic representation of the smectic C phase structure for polymers 3b and 3c. The d-spacing, molecular length, and tilt angle are indicated in the figure.