-
(1) 红外光谱
如红外光谱图2所示,产物在1600 cm−1、1630 cm−1处有较强的吸收峰,归属于苯环上C=C的伸缩振动峰,而在1440 cm−1、1385 cm−1处的吸收峰对应吡咯环上C-N 的伸缩振动峰,在2920 cm−1和1396 cm−1处出现-CH3的伸缩振动峰,以及1735 cm−1处的C=O伸缩振动峰,这均证明已合成出了不对称氯代铟卟啉引发剂。
(2) 1H核磁共振谱
图3为不对称氯代铟卟啉引发剂的1H核磁共振谱,其中δ=8.83 ppm处为吡咯环上质子的化学位移,δ=8.21 ppm处为苯环上的邻位质子峰,苯环上的间、对位质子峰出现在δ=7.75 ppm处,δ=7.21 ppm处为酯基所在苯环的间位质子峰,δ=4.80 ppm和δ=1.97 ppm处分别为与氯原子相连的α位和β位碳上的质子的化学位移,无金属卟啉环内和羟基上的质子吸收峰都消失,图中峰面积与对应氢的个数成正比。
(3) 紫外-可见吸收光谱
如图4是不对称氯代铟卟啉引发剂的紫外-可见吸收光谱,有两种类型的吸收带,分别是电子从基态S0跃迁至第二激发单重态S2产生的一个Soret带和跃迁至第一激发单重态S1产生的较弱的Q带。Soret带为卟啉化合物的特征吸收带,位于416 nm处,Q带出现于563 nm和643 nm。
-
(1) 原子转移自由基聚合动力学研究
经GPC测试,聚合时间分别为2、3、4和5 h所得InClPor-MMA聚合物的分子量和转化率数据如表1所示,聚合度分别为16、20、26、31。
表 1 聚合物分子量分布
Table 1. Polymer molecular weight distribution
Polymers Polymerization time/h Mn, GPC PDI Conv./% InClPor-MMA16 2 2414 1.11 14.26 InClPor-MMA20 3 2865 1.13 20.41 InClPor-MMA26 4 3396 1.16 27.97 InClPor-MMA31 5 3904 1.21 34.72 InClPor-MMA聚合物的动力学转化曲线、分子量及分散度分布曲线如图5、图6所示。
图 5 InClPor-MMA聚合物的一级动力学及转化率曲线
Figure 5. First order kinetics and conversion curve of InClPor-MMA polymer
图 6 InClPor-MMA聚合物的分子量及分散度分布曲线
Figure 6. Distribution curve of molecular weight and dispersion of InClPor-MMA polymer
由图5可以看出,随着单体转化率的增大,聚合物的数均分子量(Mn)呈线形增长,说明ATRP反应对聚合物分子具有良好的可控性。随着单体转化率的增高及聚合时间的增长,分子量的分布指数(PDI)呈逐步增大的趋势,但仍可以保持在1.11~1.21这个较小的范围内,符合活性聚合的基本条件。动力学曲线图6是ln([M]0/[M]t)(初始单体浓度[M]0与反应时间t时的单体浓度[M]t比值的对数)和反应时间的关系图。图中显示两者呈现良好的线形关系,说明此聚合反应符合是一级动力学,同时,增长型自由基的浓度在聚合进行的过程中始终保持不变,而且单体转化率也随反应进行时间的增长而增加,但随反应时间的逐渐增长,增加趋于平缓,这是由于反应时间延长而使部分活性种失活,符合活性可控聚合的特点。
(2) 红外光谱
图7为聚合物的红外光谱图,在2950 cm−1和1455 cm−1左右处出现-CH3的伸缩和弯曲振动峰,在1450 cm−1左右处的吸收峰属于苯环上-CH2-的剪式振动,且1735 cm−1处出现C=O的伸缩振动峰,而且随着聚合度的增大,重复链段处吸收峰的强度明显增大。
图 7 聚合物的红外光谱图 a-InClPor-MMA16, b-InClPor-MMA20, c-InClPor-MMA26和 d-InClPor-MMA31
Figure 7. Infrared spectra of the polymers a-InClPor-MMA16, b-InClPor-MMA20, c-InClPor-MMA26 and d-InClPor-MMA31
(3) 紫外-可见吸收光谱
图8为聚合物的紫外-可见吸收光谱,从图中可以看出InClPor-MMA聚合物均有一个Soret带和两个Q带,随着聚合物分子量的增大,峰强逐渐减低。与单羟基苯基卟啉相比,Soret带和Q带均发生了蓝移,这是因为甲基丙烯酸甲酯的高分子重复链段使侧基的吸电子效应增强,而且随着聚合度的增大,对侧基的吸电子效应影响越大。
-
将聚合物样品分别溶解在DMF溶剂中进行Z-扫描测试,实验中所用激光光源为倍频锁模Nd:YAG皮秒脉冲激光系统,输出激光波长为532 nm,脉冲能量为1.08 μJ,脉冲宽度为21 ps,频率为10 Hz,所用光束为top-hat光束,top-hat光的孔径光阑为4.8 mm,小孔半径为1.5 mm,小孔透过率17%,透镜焦距400 mm。经计算衍射长度为3.4 mm,样品池的厚度为2 mm,此时样品相当于薄样品。
在该实验条件下四个样品的闭孔、开孔Z-扫描曲线如图9和图10所示。
图 9 样品的闭孔Z-扫描归一化透射率曲线 (a) InClPor-MMA16, (b) InClPor-MMA20, (c) InClPor-MMA26,(d) InClPor-MMA31
Figure 9. Closed aperture Z-scan normalized transmittance curves of samples (a) InClPor-MMA16, (b) InClPor-MMA20, (c) InClPor-MMA26,(d) InClPor-MMA31
图 10 样品的开孔Z-扫描归一化透射率曲线 (a) InClPor-MMA16, (b) InClPor-MMA20, (c) InClPor-MMA26, (d) InClPor-MMA31
Figure 10. Open aperture Z-scan normalized transmittance curves of samples (a) InClPor-MMA16, (b) InClPor-MMA20, (c) InClPor-MMA26, (d) InClPor-MMA31
由图9可以看到,四个样品的透过率曲线都出现先谷后峰的情况,并且折射率都是正值,由此判断出产生了自聚焦效应,同时峰谷具有不对称性,波谷的强度明显大于波峰,说明不对称铟卟啉聚合物具有非线性吸收的特性。不同脉冲宽度激光对卟啉类材料样品的吸收测试表明,所制备的聚合物中的双光子吸收可以不考虑,非线性吸收源自于激发态吸收。
开孔条件下,样品的归一化透射率曲线为下式所示:
$$ T({\textit{z}},S = 1) = \sum\limits_{m = 0}^\infty {\dfrac{{{{[ - {q_0}({\textit{z}},0)]}^m}}}{{{{(m + 1)}^{3/2}}}}},m=0,1 $$ (1) 式中,
$$ {q_0}({\textit{z}},t) = \beta {I_0}(t){L_{eff}}/(1 + {{\textit{z}}^2}/{\textit{z}}_0^2),{\textit{z}}=0 $$ (2) $$\beta (MKS) = \frac{{4(1 - T(0))}}{{{I_0}{L_{eff}}}}$$ (3) 其中,T为透过率;β为样品的非线性吸收系数;I0光功率密度;Leff=(1-e−αL) /α为有效样品厚度,α是样品的线性吸收系数;z为样品距焦点的距离。
在
${\textit{z}} = 0$ 处的瞬时光强为I(0)。当$\;\beta $ 值不是很大时,公式(3)可以取一级近似,得$$\beta = \frac{{{{\textit{z}}^{\frac{3}{2}}}[1 - T(0)]}}{{I(0){L_{eff}}}}$$ (4) $${\chi ^{(3)}} = \chi _R^{(3)} + i\chi _I^{(3)}$$ (5) $$\chi _R^{(3)}(MKS) = 2n_0^2{\varepsilon _0}c\gamma $$ (6) $$ \chi _I^{(3)}(MKS) = \dfrac{{n_0^2{\varepsilon _0}{c^2}}}{\omega }\beta $$ (7) 式中:T(0)是z=0处的开孔透射率。
对图9和图10实验数据进行拟合和计算,得到的结果如表2所示。
表 2 聚合物的三阶非线性测试结果
Table 2. Third-order nonlinear test results of polymers
Polymers β/m·W-1 γ/esu χ(3)/esu InClPor-MMA16 3.3×10−11 3.2×10−19 11.44×10−13 InClPor-MMA20 2.8×10−11 2.7×10−19 9.69×10−13 InClPor-MMA26 1.85×10−11 4×10−19 6.92×10−13 InClPor-MMA31 0.44×10−11 2.9×10−19 2.75×10−13 从表中可以看出,全部样品均具有较好的三阶非线性光学性质,并且随着聚合度增大,不对称氯代铟卟啉聚合物的三阶非线性系数明显减小,聚合物的聚合度为16,分子量是2414时,其三阶非线性极化率值最大,为1.144×10−12 esu。这是由于随着分子链的延长,功能端氯代铟卟啉在聚合物中的浓度比例下降,并且主要影响非线性吸收系数,对非线性折射率的影响不大。
Preparation and optical nonlinearity of PMMA living radical polymerization materials functionalized with indium chloride porphyrin (Invited)
-
摘要:
合成了5,10,15-三苯基-20-(4-羟基苯基)氯代卟啉铟,采用2-氯丙酰氯对其封端作为引发剂,以甲基丙烯酸甲酯为单体,CuCl/PMDETA为催化体系,通过原子转移自由基聚合得到了不对称卟啉铟末端功能化的线形聚甲基丙烯酸甲酯。通过UV-vis、FT-IR和1H-NMR进行结构表征。利用凝胶渗透色谱对聚合物的分子量及分子量分布指数进行测定,测试结果表明,聚合物的分散度范围为1.11~1.21,分子量分布较窄,聚合反应具有良好的可控性。 采用倍频锁模Nd:YAG皮秒脉冲激光系统,在输出激光波长532 nm,脉冲宽度21 ps的条件下,利用Z-扫描对系列卟啉化合物的三阶非线性光学性质进行了测试分析,通过对实验数据的模拟和计算表明,聚合度为16,分子量为2414的聚合物三阶非线性极化率值最大,为1.144×10−12 esu。 Abstract:5,10,15-triphenyl-20-(4-hydroxyphenyl) chloroporphyrin indium was synthesized. Using 2-chloropropionyl chloride end-capped mono-hydroxy metalloporphyin as initiator, methyl methacrylate as monomer and CuCl/PMDETA as the catalyst system, a new linear polymethylmethacrylate (PMMA) with asymmetric indium porphyrin end functionalized was synthesized by atom transfer radical polymerization (ATRP) method. The structure of porphyrin compounds was characterized by Fourier transform infrared spectroscopy (FT-IR), ultraviolet-visible spectroscopy (UV-vis) and nuclear magnetic resonance hydrogen spectrum (1H NMR) techniques. Molecular weight and molecular weight distribution of the linear polymers were obtained by gel permeation chromatography (GPC). It indicated that the molecular weight distribution was narrow and the molecular weight distribution range was between 1.11 and 1.21. Meanwhile, the polymerization reaction had a good controllability. By Z-scan method, the third-order nonlinear optical properties of porphyrin compounds were tested using a frequency-doubled mode locked Nd: YAG picosecond laser system at wavelength of 532 nm with 21 ps pulse, the results showed that the third-order nonlinear polarizability (χ(3)) of polymer with polymerization degree of 16 and molecular weight of 2414 is 1.144 × 10−12 esu. -
表 1 聚合物分子量分布
Table 1. Polymer molecular weight distribution
Polymers Polymerization time/h Mn, GPC PDI Conv./% InClPor-MMA16 2 2414 1.11 14.26 InClPor-MMA20 3 2865 1.13 20.41 InClPor-MMA26 4 3396 1.16 27.97 InClPor-MMA31 5 3904 1.21 34.72 表 2 聚合物的三阶非线性测试结果
Table 2. Third-order nonlinear test results of polymers
Polymers β/m·W-1 γ/esu χ(3)/esu InClPor-MMA16 3.3×10−11 3.2×10−19 11.44×10−13 InClPor-MMA20 2.8×10−11 2.7×10−19 9.69×10−13 InClPor-MMA26 1.85×10−11 4×10−19 6.92×10−13 InClPor-MMA31 0.44×10−11 2.9×10−19 2.75×10−13 -
[1] Rao S V, Srinivas N K M N, Rao D N, et al. Studies of third-order optical nonlinearity and nonlinear absorption in tetra tolyl porphyrins using degenerate four wave mixing and Z-scan [J]. Optics Communications, 2000, 182(1-3): 255-264. doi: 10.1016/S0030-4018(00)00808-7 [2] Wu Xingzhi, Zhou Wenfa, Shen Lei, et al. Conjugated twistacene as high-performance optical limiting material for ultrafast broadband laser protection [J]. Infrared and Laser Engineering, 2019, 48(11): 1103001. doi: 10.3788/IRLA201948.1103001 [3] Terazima M, Shimizu H, Osuka A. The third-order nonlinear optical properties of porphyrin oligomers [J]. Journal of Applied Physics, 1997, 81(7): 2946-2951. doi: 10.1063/1.364325 [4] Zhang Jian, Song Yinglin, Yan Xiusheng, et al. Twistacene-modified heteroarenes: synthesis, characterization and optical limiting response [J]. Infrared and Laser Engineering, 2019, 48(11): 1103005. doi: 10.3788/IRLA201948.1103005 [5] Ma Pengfei, Liu Dajun, Zhou Fenguo. Study on preparation and performance of nonlinear optical limiting of polymers material containing indium phthalocyanine and graphene oxide [J]. Infrared and Laser Engineering, 2020, 49(1): 0107001. [6] Blau W, Byrne H, Dennis W M, et al. Reverse saturable absorption in tetraphenylporphyrins [J]. Optics Communications, 1985, 56(1): 25-29. doi: 10.1016/0030-4018(85)90059-8 [7] Liu M O, Tai C H, Wang W Y, et al. Microwave-assisted synthesis and reverse saturable absorption of phthalocyanines and porphyrins [J]. Journal of Organometallic Chemistry, 2004, 689(6): 1078-1084. doi: 10.1016/j.jorganchem.2004.01.017 [8] Zheng Wenqi, Shan Ning, Fa Huanbao, et al. Optical limiting properties of porphyrin monomers and dimers [J]. Journal of Jilin University(Science Edition), 2013, 51(1): 135-139. [9] Li D J, Gu Z G, Zhang J. Auto-controlled fabrication of a metal-porphyrin framework thin film with tunable optical limiting effects [J]. Chemical Ence, 2020: 11. [10] Hafiz Muhammad Asif,Arshad Iqbal,Yunshan Zhou, et al. Preparation, characterization and third order optical nonlinearities of looped covalently bonded Anderson-type polyoxometalate-porphyrin hybrids [J]. Dyes and Pigments, 2021, 184: 108758. doi: 10.1016/j.dyepig.2020.108758 [11] Xiao Y H, Gu Z G, Zhang J. Vapor-assisted epitaxial growth of porphyrin-based MOF thin film for nonlinear optical limiting [J]. Science China-Chemistry, 2020, 63(8): 1059-1065. [12] Wang A, Cheng L, Chen X, et al. Efficient optical limiting of polypyrrole ternary nanohybrids co-functionalized with peripherally substituted porphyrins and axially coordinated metal-porphyrins [J]. Dalton Transactions, 2019, 48: 14467-14477. [13] Jiang P, Zhang B, Liu Z, et al. MoS2 quantum dots chemically modified with porphyrin for solid-state broadband optical limiters [J]. Nanoscale, 2019, 11(43): 20449-20455. doi: 10.1039/C9NR06604G