Two novel hyperbranched poly (aryl ether)s with azobenzene moieties in both the main chain and side chain of the branched arms were prepared by using B 3 + A 2 methodology via a nucleophilic aromatic substitution polycondensation. Structures of the hyperbranched poly (aryl ether)s with azobenzene moieties (azo-HPAEs) were characterized by means of IR, UV-visible, 1 H NMR spectroscopy, and XRD. It is shown that both the azo-HPAEs exhibit high glass transition temperatures (T g ), excellent thermal stability and homogeneous photochromic behavior. By exposing their spin-coating films to an interference pattern of laser beam, both the azo-HPAEs could be used for rapid (within 30 s) fabrication of surface-relief gratings (SRGs). The obtained SRGs present no shape changes even at temperatures up to 200 C. Especially, the azo-HPAE with azobenzene moieties in the side chain shows larger photoinduced birefringence intensity and better reversible optical storage than the one with azobenzene moieties in the main chain upon irradiation with 532 nm Nd:YAG laser. The novel azo-PAEs are photoactive to UV light (355 nm), making them potentially useful for high density information storage.
When minimum shift keying (MSK)'s carrier is changed as the linear frequency modulation (LFM) signal, it is called as MSK-LFM for short. It is a new type of the radar-communication multifunctional integrated waveform. Under the assumption that the bandwidth of the radar receiver is equal to that of the LFM signal, the energy leakage of MSK-LFM is analysed. The trade-off between the number of modulated bits and the energy leakage is derived analytically. The derived equation demonstrates that the relationship between the radar detection performance and digital communication performance of MSK-LFM, which also gives the principle of designing the integrated waveform. To better ensure the radar detection performance, a method is proposed to reduce the energy leakage at the expense of sacrificing certain communication capacity.
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