Spectrofluorometric analysis and electrical conductivities of styrene and methylmethacrylate polymers by adding symmetrical polymethine dyes

To see the effect of conjugation on molecular weight and conductivity, three symmetrical polymethine dyes are added in polymers either before or after polymerization. Dyes have conjugated bonds between nitrogen atoms. Among three dyes, it was observed that as conjugation increases, the conductivity also increases. Previous study with polyethylvinylketone and polymethylvinylketone support the idea that increased conjugation will increase the molecular weight and conductivity. For these polymers also, the dopant, phosphorylchloride increased the conductivities due to the double bond being transferred to the main chain and increased conjugation. The same method developed in this work can be applied to methyl methacrylate and styrene polymers to see the relationship between molecular weight, conductivity, and fluorescence intensity. When dyes were added to methylmethacrylate and styrene monomers before polymerization, much higher conductivities were obtained. Conductivity values are directly proportional to the irradiation times and molecular weights. Four‐hour irradiation time results in a maximum molecular weight of 6.4 × 10⁵ and a maximum conductivity of 2.25 μS for MMA polymers. Spectrofluorometric analysis of methyl methacrylate polymers indicates that as molecular weight of the dyes increases, the emission intensities at 375 and 425 nm also increases. In the same way, increased molecular weight of polymer also results higher emission intensities. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

六羰基钨催化制备聚苯乙炔及其荧光性能的研究

用W(CO) 6 催化体系聚合苯乙炔 ,以高产率获得较高相对分子质量的聚苯乙炔。使用UV、IR、GPC等分别对聚苯乙炔结构进行表征。采用不同波长的激发光对聚苯乙炔荧光性能进行了详细研究 ,结果表明 :当聚苯乙炔用 31 0nm激光激发时 ,呈现 3个荧光发光峰 ,峰值分别在348、396和 61 0nm处 ,与其溶液的紫外吸收有类似的光谱曲线特征。荧光峰在 348nm处的荧光 ,当聚苯乙炔质量浓度大于 0 0 5g L时 ,呈现荧光猝灭效应 ;在聚苯乙炔质量浓度为 1 0 - 4g L时 ,呈现出最大的荧光发光量子效率。当激发光波长低于 2 70nm和高于 340nm时 ,348nm波长荧光消失 ;荧光峰在 396nm处的荧光 ,当聚苯乙炔的质量浓度为 1 0 - 2 g L时 ,呈现最大的发光量子效率 ,聚苯乙炔的质量浓度增大或降低 ,其发光强度均呈现减弱现象 ;荧光峰在 61 0nm的荧光 ,在聚苯乙炔质量浓度为 1 0 - 4g L时 ,呈现最大的发光量子效率。荧光性能研究结果证明这种催化剂获得的聚苯乙炔具有多种异构链结构。     

Reversible addition-fragmentation chain transfer polymerization of 7-(4-(acryloyloxy)butoxy)coumarin

The light sensitive vinyl monomer with coumarin unit, 7-(4-(acryloyloxy)butoxy)coumarin (7AC), was synthesized. The reversible addition-fragmentation chain transfer (RAFT) polymerization of 7AC, initiated by 2,2′-azobisisobutyronitrile (AIBN), was carried out using 2-cyanoprop-2-yl dithiobenzoate (CPDB) as a RAFT agent in N,N-dimethylformamide (DMF) solution. The kinetics exhibited first-order relationship with respect to the monomer concentration. The molecular weight of the polymer increased linearly with the monomer conversion. The chain extension of poly(7-(4-(acryloyloxy)butoxy)coumarin) (P7AC) using styrene (St) as the second monomer demonstrated that the obtained polymers were almost “living”. The fluorescence intensity of P7AC increased with the molecular weight of P7AC and was stronger than that of the monomer. The obtained polymer had strong ultraviolet (UV) absorption at 322 nm. The molecular weights of the polymer had no effect on its ultraviolet absorption intensity. The coumarin structure existing in P7AC underwent [2 + 2] cycloaddition reaction (photodimerization) under UV irradiation in tetrahydrofuran (THF) solution, which can be further used to prepare small particles from the single polymer.     

Efficiency of Gold Nano Particles on the Autoxidized Soybean Oil Polymer: Fractionation and Structural Analysis

Polyunsaturated plant oils have gained great interest as monomers to produce biodegradable polymers obtained from renewable resources due to the limited existing sources of petroleum oil and environmental issues. Soybean oil was autoxidized by exposure to atomospheric oxygen at room temperature with or without the presence of gold nanoparticles (Au NPs) 5–41 days. When the autoxidation process was catalyzed with Au NPs, the molecular weight of the oxidized oil was increased in 5 days. In contrast to this, without Au NPs, the oxidized oil was still a fluidized liquid. Autoxidized soybean oil polymer in toluene solution with gold NP showed a surface plasmon resonance at λ_max = 540 nm in a UV–VIS spectrometer and a fluorescence emission spectrum at λ_max = 450 nm, when it was irradiated at λ_max = 390 nm. The higher molecular weight of the polymeric oils was successively fractionated by the extraction from the solvent‐non‐solvent mixture CHCl₃/petroleum ether with the volume ratio of 5:15. Three polymeric oils fractions with different molecular weight (ca 1000, 4000, and 40,000 g/mol) were obtained. GC–MS analysis, ¹H‐NMR and GPC techniques were used in the structural analysis of the fractionated polymeric oils.     

Synthesis and physical properties of liquid‐crystalline copolymers with azobenzene segments

To investigate the effects of photoisomerizable azobenzene segments on the liquid‐crystalline characteristics and thermal properties of polymers, a series of liquid‐crystalline homopolymers and copolymers with azobenzene segments was synthesized. The azobenzene contents of the copolymers were estimated with elemental analysis. The photoisomerization of the azobenzene derivatives was studied with ultraviolet–visible (UV–vis) spectroscopy. The UV–vis absorption of the copolymers was found to be parallel with the content of the azobenzene segments. UV irradiation was found to cause a decrease in the copolymer transmittance around 355 nm due to the photoinduced isomerization from entgegen (E) to zusammen (Z). The phase‐transition temperatures and molecular weights of the polymers were investigated with differential scanning calorimetry and gel permeation chromatography, respectively. The variation in the phase‐transition temperature of the homopolymers before and after UV (365 nm) irradiation was investigated. The bended Z structure was found to disturb the order of the orientation of liquid crystals and to lower the phase‐transition temperature. The appearance of the polymer film was changed from opaque to clear after sufficient UV irradiation. The image recording of the polymer films was achieved after UV irradiation through a mask with pictures. The stability and reliability of the Nematic‐Isotropic phase transition of the homopolymers was evaluated with repeated cycles of 365‐nm UV irradiation and heating at 130°C. After the recycle phase transition was repeated nine times, no significant decay in the response and transmittance could be found. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 2006     

Photobase‐generating new polyurethanes with oxime–urethane groups in the main chain

New polymeric photobase generators containing oxime–urethane groups were prepared by the polyaddition reaction of 2,4‐tolylene diisocyanate with terephthalaldehyde dioxime in the presence or absence of a polyol component to study the ability of these polymers to generate amines through the photolysis of oxime–urethane linkage. The amines induced the crosslinking of poly(glycidyl methacrylate), as proved by the variation of the amount of the insoluble fraction of polymer films with the heating temperature and/or irradiation time. UV and IR absorption spectra indicated that the thermal crosslinking of poly(glycidyl methacrylate) was catalyzed by the photogenerated amines. The photobehavior of the polymers was followed by a reduction of the absorption band at 290 nm, which was characteristic of oxime–urethane groups, as a function of the UV irradiation time. Blue fluorescence was visualized by the treatment of irradiated films with fluorescamine. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 2324–2332, 2004     

Luminescence studies in poly(ethylene terephthalate) films at 77 K. Investigation of emission centres in polymers

Optical luminescence of amorphous bright poly(ethylene terephthalate) (PET) films and the changes in luminescence due to certain morphological changes have been studies at 77 K to identify the luminescent centres in this polymer. The emission spectrum consists of both fluorescence and phosphorescence with distinct band peaks at 304, 326, 365 nm corresponding to fluorescence and at 426, 453, 476 nm corresponding to phosphorescence. Comparison of the PET emission spectrum with that one from dimethyl terephthalate microcrystals indicates that the emitter in the polymer is most probably the basic terephthalate unit. Polarized absorption and emission studies in oriented and unoriented PET films also support this observation. Change in the relative intensity distribution on changing the crystallinity of the film suggests that each of the 304, 326 and 365 nm fluorescence bands arises from different environments of the emitting centre. On γ-irradiation, a large increase in emission intensity is observed. This is explained on the basis of formation of a radical which in turn causes a large inductive effect on the benzene rings.     

A thermoplastic polyurethane/rare earth composite film with adjustable fluorescence colors and optimal low-temperature flexibility

In this study, a unique series of luminous polymeric rare earth (RE) composite films was produced by loading RE ions into thermoplastic polyurethane (TPU) using solution blending. Compared to RE ions, luminous polymeric RE composites had greater luminescence intensity, indicating that the introduction of polymer polyurethane as the polymer matrix was advantageous for the luminescence intensity and efficiency of RE ions, with the polymer matrix's absorbed energy being transferred to the RE ions. Furthermore, the findings of the optical transmittance, UV–visible absorption and fluorescence emission spectra suggest that TPU-RE composite films possess exceptional fluorescence luminescence properties and optical transparency. Surprisingly, the fluorescence colors of TPU-RE fluorescent films could be adjusted between red and green by varying the ratios of Eu³⁺ and Tb³⁺ in the films and can be any mixture of red and green hues. In addition, the temperature at 5% weight loss (T_5%) for the TPU-RE composite film composition reached 250 °C. In addition, pure TPU and all TPU-RE hybrid films demonstrated a glass transition temperature (T_g) of about −30 °C. Simultaneously, the tensile strength of the TPU-T₀E₁₀ film reached its maximum (43.6 MPa). Consequently, the TPU-RE composite films will be utilized as photoluminescent functional materials. © 2022 Society of Industrial Chemistry.     

Synthesis and fluorescence studies of dual-responsive nanoparticles based on amphiphilic azobenzene-contained poly (monomethyl itaconate)

Here photo- and pH-responsive behavior of polymer micelles formed by synthesized azo-modified poly (monomethyl itaconate)s (PMMI-Azo) with appropriate amounts of azobenzene side groups (DS_Azo) were reported. The PMMI-Azo polymer with DS_azo?=?20 was used for the preparation of micelles using dialysis method. Self-assembly behavior of the PMMI-Azo was studied by transmission electron microscopy (TEM), fluorescence spectroscopy, dynamic light scattering (DLS) and UV–Vis spectrophotometry techniques. It was found that the PMMI-Azo polymers self-assembled into spherical micelles with core-shell structures. TEM images and DLS analysis of the PMMI-Azo-20 micelles showed regular spherical micelles which increased in size and polydispersity index after UV irradiation, caused by isomerization. It was also found that with increasing the polymer concentration, the fluorescence intensity decreased obviously which could be attributed to the interactions between the closely located pyrene and azobenzene in the micelles core. Experimental results suggested that the micellization-enhanced fluorescence was caused by a slowdown in the rate of the trans-to-cis photoisomerization. Furthermore, it was found that the fluorescence intensity of the aqueous micellar solutions was sensitive to stimulus such as pH change and UV light irradiation, as a result of alteration in aqueous micellar association. The results clearly indicated the role of UV irradiation and pH in the state of the polymer micellar association which is responsible for fluorescence intensity.     

Branched polysilanes from tetrafunctional monomers

Tetrafunctional silicon monomers have been incorporated into soluble branched polysilanes. Tetrakis(chlorodimethylsilyl)silane has been homopolymerized to form an irregular branched polymer which may contain some spiro and some bicyclic units. This polymer shows weak absorption at 300 nm, the region of the linear polysilane chains. It emits broadly in the region from 400 to 500 nm. The copolymers of tetrakis(chlorodimethylsilyl)silane with dichlorodimethylsilane are also soluble and in the presence of l ge amount of the tetrakis monomer emit in the region from 400 to 500 nm. By contrast, copolymers with phenyltrichlorosilane emit strongly at 450 to 650 nm, due to the phenylsilane hyperbranched structure. Small amounts of tetrachlorosilane can be incorporated into soluble polysilanes. Incorporation of =Si=units into polymers withn-hexyl substituents is very inefficient but leads to minor changes in emission spectra. Incorporation into polymers with phenyl substituents affects luminescence and increases molecular weights and broadens polydispersities. Reaction with dimethyldichlorosilane provides soluble low molecular weight oligomers and polymers. Polymers prepared with a small proportion of tetrachlorosilane show absorption and emission typical for linear polymers. Polymers synthesized with higher proportion of tetrachlorosilanes emit broadly at 400 to 500 nm, indicating the presence of Si clusters. The silicon clusters entrapped into soluble polymers are very easily oxidized as seen by the siloxane peaks in²⁹Si NMR spectra and they should be treated under complete exclusion of oxygen.     

4—甲酰基4—苯乙烯基吡啶分子聚集行为的光谱研究

苯乙烯基吡啶化合物,由于它可能在医学方面和光电子功能材料方面有实际应用前景,已引起人们的兴趣。苯乙烯吡啶化合物的光化学性质类似于二苯乙烯化合物,在光照下可以发生顺-反异构反应、加成反应和二聚反应等不同的光化学反应。但苯乙烯     

Synthesis and characterization of novel multifunctional poly(methyl methacrylate)s as potential fluorescent labels for electron‐beam lithography

A series of novel fluorophore‐rich polymers has been synthesized with the aim of developing radiation‐sensitive materials as electron‐beam resists. The polymers were characterized using FTIR and NMR spectroscopy, and gel permeation chromatography, differential scanning calorimetry and thermogravimetric analysis measurements. These polymers showed strong absorbance in the region of 330–380 nm, and can be patterned by an electron‐beam in their pure form or mixed with other components. All polymers also generated intense emission in the range 510–565 nm when irradiated by a laser source operating at a wavelength of 488 nm. The sensitivity of the polymeric fluorescence label as an electron‐beam resist was also discussed. Moreover, through immobilization of the fluorophores onto a polymer backbone, we managed to avoid the crystallization of fluorophores inside the polymer film. Copyright © 2005 Society of Chemical Industry     

Fluorescence upconversion properties of a chiral polybinaphthyl induced by two‐photon absorption

The fluorescence properties of a chiral polymer based on optically active polybinaphthyls were studied in tetrahydrofuran solution. One‐photon excited fluorescence of the polymer was located in the range of ～ 596 nm and the corresponding lifetime was ～ 4.38 ns. From the excitation spectra and emission spectra excited at 800 nm, the upconversion fluorescence emission was observed. When excited by using 800 nm fs laser pulses with different input irradiances, the peak fluorescence intensity of the solution provides square dependence with the input irradiance power, giving an evidence for two‐photon excited fluorescence. Furthermore, open aperture Z‐scan measurements were performed at different irradiation intensities to confirm two‐photon absorption property of the solution at 800 nm excitation. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Synthesis and properties of fluorenyl–pyridinyl alternatingcopolymers for light‐emitting diodes

A novel series of well‐defined alternating poly[2,7‐(9,9‐di(2‐ethylhexyl)fluorenyl)‐alt‐pyridinyl] (PDEHFP) copolymers were synthesized using palladium(0)‐catalyzed Suzuki coupling reaction in high yields. These polymers were characterized using ¹H NMR, UV‐visible and fluorescence spectroscopies, gel permeation chromatography, thermal analysis and cyclic voltammetry. The optical properties of the copolymers, including photoluminescence (PL) and electroluminescence (EL), were studied. The difference in linkage position of pyridinyl units in the polymer backbone has significant effects on the electronic and optical properties of polymers in solution and in film state. Meta‐linkage (3,5‐ and 2,6‐linkage) of pyridinyl units in the polymer backbone is more favorable for pure blue emission and prevention of aggregation of polymer chains. PDEHFPs with 2,6‐ and 3,5‐linkage of pyridinyl units have relatively high PL efficiency of 37 and 44% in the film state. In comparison with homopolymer PDEHF, the copolymers with pyridinyl units possess low lowest unoccupied molecular orbital energy levels for easy electron injection from a cathode. Strong EL is observed and light‐emitting diodes (LEDs) exhibit typical rectifying characteristics. The emission intensity starts to increase at around 12 V. The emission peak wavelengths of the polymers roughly coincide with those of PL. This series of fluorene–pyridine‐based alternating copolymers seem to be candidates for polymeric LEDs. © 2013 Society of Chemical Industry     

Viscous behavior of polymerized vegetable oils

Summary Extraction of thermally polymerized linseed oil with acetone at various temperatures yielded fractions at higher temperatures that had high molecular weights and gave intrinsic viscosity and critical miscibility plots resembling those of high polymers. Unheated oil was not an indifferent solvent for polymerized oil as judged by the temperature coefficient of intrinsic viscosity. Molecular weight information obtained with non-randomized samples suggested a linear relation between log viscosity and (Mn)1/2 for molecular weights up to 2,500. With weight average molecular weights, a linear relation between log viscosity and (Mw)1/2 obtains at molecular weights greater than 40,000. Randomization of the samples decreased their bulk viscosity while increasing polymer content. Contribution No. 374, Chemistry Division, Science Service, Ottawa. Presented, in part, at the 29th Fall Meeting, American Oil Chemists' Society, Philadelphia, Pa., October, 1955.     

Er^3＋掺杂量对Er^3＋：BaY2F8晶体上转换发光性能的影响

利用温度梯度法生长了Er3＋：BaY2F8晶体。测量了样品的吸收谱、上转换荧光发射谱和上转换发光强度与激光泵浦功率的对数关系;分析了Er3＋的上转换可见发光机制和Er3＋掺量对Er3＋：BaY2F8晶体发光强度的影响。结果表明,在相同泵浦功率的980 nm光激发下的Er3＋：BaY2F8晶体的上转换发射谱中,552 n...     

The gamma-ray-induced crosslinking of polyacrylamide

The gamma-ray-induced crosslinking of polyacrylamide was carried out under various conditions. The molecular weight of the polymer before inrradiation was found to be the most important factor for crosslinking. When polymers have low molecular weights such as 80,000, the intensity of radiation, the external pressure applied, and the water content of the polymer powder became important for crosslinking. Although the polycrylamide hydrogel can be obtained directly by irradiating the monomer, it was obtained more conveniently by the irradiation of monomer—polymer mixtures. The hydrogels obtained by the radiation with a dose of over 50 kgray, absorb water by 1000–1500 wt %.     

Photo-induced change in wettability and binding ability of azoaromatic polymers

Photochromic polymers containing p-phenylazoacrylanilide were synthesized and the photo-induced hydrophobicity change on the surface of the polymer film was studied by measuring water wettability. The wettability increased with UV irradiation and returned to the original value with visible light irradiation. This photo-induced reversible change in wettability was considered to be caused by the large change of dipole moment across the azo bonds due to the isomerization of azo dye from trans to cis form. Furthermore, the photoresponsive polymeric adsorbent prepared from the azo polymer having adsorption behavior of a low molecular weight compound was studied. The binding ability of this polymeric adsorbent was decreased by UV irradiation. These results were attributed to the decreased hydrophobic interaction between the adsorbent and the adsorbate.     

Novel π-conjugated organoboron polymers: Poly (ethynylene-phenylene-ethynylene-borane)s

Summary Novel poly(ethynylene-phenylene-ethynylene-borane)s were prepared by polycondensation between bifunctional lithium acetylide and aryldimethoxyborane. The polymers obtained are expected as a novel type of organoboron π-conjugated polymers via vacant p-orbital of boron atom. The polymerization between dilithium 2,5-didodecyloxybenzene- 1,4-diethynilide and tripyldimethoxyborane [tripyl=2,4,6-triisopropylphenyl] gave the corresponding polymer in 67% yield. From gel permeation chromatographic analysis (THF, PSt standards), the number-average molecular weight of the polymer was found to be 2700. In the UV-vis spectrum of the polymer (in chloroform at room temperature), an absorption maximum was observed at 397 nm. The fluorescence emission spectrum (in chloroform, room temperature, excitation wavelength at 400 nm) showed its λ_max at 456 nm in the visible blue region. The polymers obtained were very soluble in common organic solvents such as THF, chloroform and benzene. Received: 11 April 2000/Accepted: 22 April 2000     

Reactions of unsaturated fatty alcohols. III. Viscosity and molecular weight studies on some vinyl ether polymers

Summary Molecular weights of the polymers of the vinyl ethers of stearyl, soybean, and linseed fatty alcohols were measured cryoscopically in cyclohexane at three different concentrations. Corrected number-average molecular weights were obtained by extrapolation to zero cocentration. For each family of polymers a series of preparations varying in degree of polymerization were studied with number-average molecular weights ranging from 1,500 to 15,000 or higher. Reduced viscosity measurements at 25°C. were made on benzene solutions of each polymer preparation at three different concentrations. Intrinsic viscosities were obtained by extrapolating to zero concentration. Intrinsic viscosities for the polymers range from 0.05 to 0.20. Logarithmic plots of molecular weightvs. intrinsic viscosity gave linear relationships for stearyl, soybean, and linseed polymers. Values forK′ anda in the equation of Mark and Houwink were obtained from these plots. Presented at fall meeting. American Oil Chemists' Society, September 23–26, 1956, Chicago, Ill.