Light fatigue resistance

The reversible electrocyclic interconversion between the colourless ring-open state and the coloured ring closed state on irradiation with light occurs at well-separated wavelengths. The thermal conversion is not favoured and the compounds show very high fatigue resistance. ... 

Fig. 2 Fatigue resistance properties of and 3 in deaerated hexane upon alternate irradiation with 313 nm and X > 440 nm light. Absorbances of la ( ) and 3a ( ) were plotted...

The enantiomers of 8 are stable at ambient temperatures (AGmc = 25.9 kcal mol-1) and fatigue resistant. Upon irradiation at 313 nm, a stereospecific photochemical isomerization process occurs, which converts P-8 into M-8 and vice versa. A fairly efficient, rapid, and selective photoracemization was observed when using unpolarized light (rac = 0.40 n-hexane). Large circular dichroism (CD) absorptions and... 

Nylon 6, or nylon caprolactam, is a polymeric fiber derived from only one constituent, caprolactam, giving the polymer [-(CH2)5CONH-] . It has a lower melting point than nylon 6,6, but it is superior to it in resistance to light degradation, elastic recovery, fatigue resistance, and thermal stability. 

Diarylethenes are promising synthetic photoswitchable molecules because of their outstanding fatigue-resistance in reversible light-induced transformation between two isomers with different absorption spectra.21,22 The tt-conjugation extends over the entire molecular in the closed form, whereas it is restricted to each half of the molecule in the open form. As a consequence, the closed form is expected to exhibit better electrical conductance than the open form. The two forms are referred to as the on and off states of the switch, respectively. The UV-vis spectra of this molecular switch in toluene show that the wavelengths that can be used for on to off switching are 420 < A< 650 nm, and 300 < A< 350 nm for the reverse operation. 

Spirooxazines have excellent resistance to light-induced degradation. This property, also called fatigue resistance, is considered to be due to photochemical stability of the oxazine molecule framework in the ring-closed form as well as in the open-ring form. The fatigue resistance of the spirooxazines has led to then-successful use in various applications, for example, eyewear. 

Figure 3. Fatigue resistance of 10 and 11 in deaerated hexane solution. Absorbances of 10a ( ) and 11a ( ) were plotted after irradiation with visible light. The visible absorbance at 547 nm ( ), which remained after visible irradiation of a hexane solution containing 11, was also plotted.

Nitrided Light case depths with fair capacity for contact loads, good bending fatigue resistance, excellent seizure resistance and good dimensional control... 

A dithienylperfluorocyclopentene derivative was reported by Lemieux et al. for the photochemical switching of polarization in SmC and this system exhibited the advantage of thermally stabOity at irradiated state over the azobenzene-doped systems [136, 137]. FLC mixtures MDW950-PhP doped with 1.0 and 3.0 mol % of 30 was irradiated with UV light (Fig. 5.23), the photoisomerization of 30 caused a destabihzation in SmC and the Ps versus temperature plots shifted to lower temperatures. The phase transition temperature from ferroelectric SmC to non-ferroelectric SmA was decreased by 2 °C upon irradiation of the 3 mol % FLC mixture. The photoswitching was bistable and fatigue resistance (Fig. 5.24). 

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