【作者】 金正能；

【导师】 路建美；

【作者基本信息】 苏州大学 ， 应用化学， 2008， 博士

【摘要】 聚合物荧光和三阶非线性光学材料既含有小分子材料优良的光学品质,又具有高分子材料优越的可加工性,因此成为荧光材料和三阶非线性材料的研究重点之一。1,8-萘酰亚胺基团是一类具有优异光学性能的发色团,通过结构设计将1,8-萘酰亚胺基团键接到聚合物中,使得到的高分子材料既保持了1,8-萘酰亚胺基团的光学性能,又具有高分子材料的优点,因此,在荧光材料和三阶非线性材料方面可能具有潜在的应用价值。原子转移自由基聚合(ATRP)和可逆加成-断裂转移(RAFT)聚合方法是近十多年来发展起来的活性聚合方法,对各种官能团具有广泛的适应性,可以通过功能性引发剂和RAFT试剂制备端基功能化的聚合物,也可以通过功能性单体的聚合得到侧链功能化的聚合物。这两种活性聚合方法为合成多种具有特殊结构和性能的聚合物提供了有效的途径。本论文以研究含1,8-萘酰亚胺基团聚合物材料的荧光和三阶非线性光学性能为出发点,设计、合成并表征了4个体系的端基含1,8-萘酰亚胺官能团或侧链含1,8-萘酰亚胺官能团的聚合物材料。这些材料都通过ATRP或RAFT聚合方法得到,一方面利用端基功能化或单体功能化得到单色荧光或三阶非线性光学材料,另一方面将端基功能化和单体功能化相结合起来,得到光谱可调的双色或多色荧光及三阶非线性光学聚合物材料。对得到的聚合物进行荧光和三阶非线性光学性能的测试,较系统的研究了聚合物的结构与性能的关系。论文主要进行了以下几个方面的工作:(1)利用ATRP端基功能化的特点制备具有绿色荧光的端基含1,8-萘酰亚胺结构的聚苯乙烯(NAPH-PSt)。采用含1,8-萘酰亚胺结构的化合物(NAPHCl)作为ATRP体系中的引发剂,考察了该引发剂引发苯乙烯的ATRP,发现聚合反应具有良好的活性/可控特征,同时考察了引发剂和聚合物的荧光性能,发现它们均具有绿色荧光,它们在DMF溶液中的最大发射都在520 nm,并且聚合物的荧光量子效率和能量效率高于小分子引发剂。(2)将ATRP的端基功能化和单体功能化相结合制备具有蓝绿双色荧光聚合物材料。合成了两种具有蓝色荧光的二苯乙烯类化合物,4’-甲氧基-4-乙烯基二苯乙烯(MEOVS)和4-(2-(1-萘基))-乙烯基苯乙烯(NVS),以NAPHCl为引发剂,引发两种二苯乙烯类单体聚合。结果发现MEOVS的聚合不可控,NVS的聚合是活性/可控的。考察了NAPH-PNVS的荧光性能,在溶液和膜状态下,NAPH-PNVS都具有较好的荧光性能,发蓝绿双色荧光,并且蓝绿光的相对强度可通过调节分子量的大小来调节。(3)在上面的研究基础上,扩展ATRP端基功能化的方式,制备双色荧光聚合物。通过对端基修饰制备得到了侧链含苯并噁唑基团,端基含萘酰亚胺基团的聚合物NAPH-PMABE。NAPH-PMABE在溶液和膜状态下都有两个荧光发射峰,其中最大发射位置在375 nm处的紫光发射峰是苯并噁唑侧链的发光,545 nm处的绿光发射峰是1,8-萘酰亚胺的荧光。此外,NAPH-PMABE具有较明显的三阶非线性光学效应,非线性吸收类型为反饱和吸收,非线性折射类型为自散焦。这种聚合物的三阶非线性光学性能是由末端腙式结构的萘酰亚胺基团引入而产生的,其良好的成膜性使器件化成为可能。(4)利用RAFT方法制备侧链含1,8-萘酰亚胺官能团的聚合物。我们合成了5种苯乙烯类和2种甲基丙烯酸酯类萘酰亚胺单体,以一种含末端带咔唑结构的聚苯乙烯为大分子RAFT试剂,考察了所得单体的RAFT聚合,发现苯乙烯类1,8-萘酰亚胺单体可以聚合,但是聚合度不高,甲基丙烯酸酯类1,8-萘酰亚胺单体RAFT聚合不可控。所有单体和聚合物都具有较好的荧光性能,在DMF中荧光不仅峰形相似,最大发射位置相同,均为558 nm。此外,所得到的萘酰亚胺单体和嵌段共聚物还具有比较明显的非线性吸收和折射,非线性吸收的类型为反饱和吸收,非线性折射的类型为自散焦,在DMF溶液中它们的三阶非线性极化系数都在10-12 esu的数量级,并且分别由非线性吸收和非线性折射的两方面贡献。更为重要的是,嵌段共聚物膜具有更好的三阶非线性光学性能,结果表明膜的非线性吸收和折射类型与溶液中一样,但三阶非线性极化系数提高了1个数量级。更多还原

【Abstract】 Presently, much attention has been devoted to polymeric materials with fluorescent and third-order nonlinear optical (NLO) properties for their great potential usages in optical and electro-optical applications. Such polymers not only remain good optical properties of small molecules, but also exhibit good mechanical properties and excellent processabilities. As one chromosphere that possessing outstanding optical properties, 1,8-naphthalimde derivatives have been promising materials in recent decades. Many endeavors have been done to design and synthesize polymers containing 1,8-naphthalimide groups. Atom transfer radical polymerization (ATRP) and Reverse addition-fragmentation transfer (RAFT) polymerization are two versatile tools to prepare functional polymers. By selecting functional initiators, RAFT regents or monomers, functional polymers with well-defined structure can be obtained.In this thesis, we focused on the design and synthesis of novel polymers containing 1,8-naphthalimide moieties for singal or composite fluorescent materials and third-order NLO materials. All polymers that have 1,8-naphthalimide groups in the end or side chain were prepared via ATRP and RAFT polymerization. The fluorescent and third-order NLO properties were studied. The work can be summarized as follows:(1)1,8-naphthalimide end functional polystyrene (NAPH-PSt) with green fluorescence were prepared via functional initiators of ATRP. We synthesized a novel 1,8-naphthalimide derivative NAPHCl as the initiator, which was used in the polymerization of styrene to obtain NAPH-PSt. The fluorescent properties of NAPHCl and NAPH-PSt were investigated. Results showed that both NAPHCl and NAPH-PSt have green emission, but the polymer has higher quantum yield and energy yield.(2) A series of polymers with blue and green di-color emission were prepared by the combination of functional initiator and monomer of ATRP. Two stilbene derivatives, 1-(4-methoxystyryl)-4-vinylbenzene (MEOVS) and 1-(4-vinylstyryl)naphthalene (NVS), were synthesized. Then, NAPHCl was selected to initiate the polymerization of MEOVS and NVS to prepare polymers NAPH-PMEOVS and NAPH-PNVS. Results show that the polymerization of MEOVS is uncontrolled and NVS is controlled. The fluorescent properties of NAPH-PNVS were investigated. Each of the obtained polymers with different molecular weight has a composite emission spectrum comprising a blue component originated from NVS and a green component originated from NAPHCl. The relative intensity of the blue and green emission bands can be easily tuned by changing the polymer chain length.(3) Based on the research of NAPH-PVS, we tried to change the method of end function of the polymer with a di-color emission prepared via ATRP. Here, a series of homopolymers, poly[(4-(benzoxazole-2-yl)phenyl)methyl methacrylate] (NAPH -PMABEs) with different molecular weight, containing benzoxazole side chains and 1,8-naphthalimide terminated end, were prepared by ATRP of (4-(benzoxazole -2-yl)phenyl) methyl methacrylate (MABE) and chemical modifications with 1,8-naphthalimide moieties. The optical properties of NAPH-PMABE were investigated. Results show that NAPH-PMABE also has a composite emission spectrum comprising an ultraviolet component originated from benzoxazole side chains and a green component originated from 1,8-naphthalimide end group both in solution and film. Besides, NAPH-PMABE has obviously third-order nonlinear optical (NLO) properties which was introduced by the end-functional moieties of 1,8-naphthalimide. The NLO properties were attributed to both nonlinear absorption and refraction.(4) A series of polymers containing 1,8-naphthalimide moieties in the side chains have been prepared via RAFT technique. Firstly, five styrene and two methyl acrylate based 1,8-naphthalimide monomers were synthesized and characterized. Then, carbazyl group terminated polystyrene (CA-PSt) was used as macromolecular RAFT agent. Thus, the well-defined copolymers (CA-NAPH-PSts) containing 1,8-naphthalimide side chains and carbazole end group were obtained only for those styrene based 1,8-naththalimide monomers. The fluorescent properties of monomers and copolymers were investigated. All monomers have strong orange emissions with the maximum wavelength at 558 nm in DMF solution. In solid films, the emission maximum wavelength of CA-NAPH-PSts is red-shifted to 572 nm. Besides, all monomers and copolymers have large third-order NLO properties. The third-order NLO coefficientχ(3) was attributed to dual contributions of nonlinear absorption and refraction of the molecules. Also, we investigated the third-order NLO properties of CA-NA6PH-PSt in film state.更多还原