Synthesis And Nonlinear Optical Properties Of Polyphenylsulfone (PPSU) Containing Anthraquinone

Macromolecular dyes exhibit broad application scopes in optoelectronics and conductive materials,such as non-linear optics(NLO),LCD,optical storage as well as dyeing the materials,due to the synergetic interactions between macromolecular backbone and the chromophore.Besides,laser is becoming more and more popular and widely employed in laser weapons,laser-beam cutting,laser medicine and so on.Owing to the potential hazard of laser to devices,human eyes and skin,laser-involved safety issues and protection measures are gaining increasing attention.Thus,it becomes a hot research topic to fabricate laser safety devices by employing the NLO effect to achieve laser limiting.Macromolecular dyes with high mechanical strength,good stability,excellent refractive index and light transmission properties are ideal candidates for investigating the NLO effect.Compared with inorganic NLO materials,organic NLO materials are advantageous due to their fast responses,large NLO coefficients and high optical damage threshold.Furthermore,polymeric organic NLO materials with feasible molecular design,high mechanical strength and excellent stability are captivating the imagination of researchers.However,so far,it remains challenging to achieve novel organic NLO optical materials with excellent stability,good optical properties and processability.In this thesis,we focus on the exploration of materials with NLO properties.By adopting the“donor-acceptor intramolecular electron and energy transfer model”strategy,we design and prepare organic-inorganic hybrid and purely organic NLO materials,both with“donor-acceptor structures”.By blending these NLO materials with poly(phenylene sulfone)(PPSU),solid films with multiple phases are achieved.We further investigate their structures,morphologies,photophysical properties,energy gaps,and NLO properties and come to the following conclusions:1.Through molecular engineering,chomophores with anthraquinone structures are obtained through condensation reaction and introduced to PPSU with excellent properties,affording colorful PPSU materials with red,yellow and blue colors,respectively.The NLO properties and NLO stability of these dyed PPSU materials are characterized with z-scanning technology.The experimental results show that the nonlinear absorption coefficient?_eff(cm GW^-1)of color PPSU film is still more than800,and the third-order nonlinear susceptibility Im^[?(3)]is still in the order of 10-10after high temperature(200?)or strong acid-base treatment,showing good nonlinear optical chemical stability.2.In order to improve the optical limiting performance of colored PPSU,we design and synthesize hyperbranched phthalocyanine decorated graphene oxide hybrid material(HLa Pc-GO)with donor-acceptor structures.The photo-induced electron transfer and energy(PET/ET)effect aroused by the donor-acceptor structure endow the hybrid materials with better NLO response than GO and HLa Pc alone.The YPPSU/Hla Pc-GO composite material prepared by exploiting the“like dissolves like”principle demonstrates even better optical limiting properties,with incident intensity threshold I_lim of 0.41 J cm^-2 and 0.41 J cm^-2 at 532 nm and 1064 nm,respectively.3.In order to settle the bad dispersity and stability issues of inorganic/organic hybrid materials in organic and polymers,we construct a novel purely organic NLO optical materials with donor-acceptor properties by covalently linking anthraquinone group(electron donor)with phthalocyanine group(electron donor)in its axial direction.The photo-induced electron and energy transfer between anthraquinone group and phthalocyanine group greatly improve the NLO properties of La Pc-Aqn and HLa Pc-Aqn,as compared with that of La Pc and HLa Pc.4.We further blend HLa Pc-Aqn with Y-PPSU to fabricate completely compatible purely organic HLa Pc-Aqn/Y-PPSU blend film.During our investigations on the films,we notice the better optical performances of HLa Pc-Aqn/YPPSU film than that of HLa Pc-Aqn in solution,which can be attributed to the high similarity of the sulphone group and anthraquinone group in HLa Pc-Aqn with Y-PPSU.The nonlinear absorption coefficient(?_eff)and third-order nonlinear susceptibility(Im^[?(3)])of HLa Pc-Aqn/YPPSU film are larger than that of HLa Pc-Aqn in solution by three order of magnification.We further employ CVS to determine the molecular energy gap and plot the transition processes of phthalocyanine in solution and film.The results indicate that energy gap between first singlet state(S₁)to first triplet state(T₁)of HLa Pc-Aqn in solid film is much smaller than that of in solution state.The small S₁ to T₁ energy gap is favorable for the intersystem crossing between S₁ and T₁ and can greatly increase the possible engagement of T₁ and T_n in the non-linear absorption process,and thus contribute to better NLO effect.The solid film of HLa Pc-Aqn/YPPSU-TF possesses excellent optical-limiting properties and demonstrates a high incident intensity threshold(I_lim)of 0.012 J cm^-2 at 532 nm laser,which is the best valued obtained to the best of our knowledge.The excellent optical limiting performance makes it an excellent candidate for preparation of optical limiting materials,which may find a variety of applications in laser safety area.