Preparation and characterization of novel ZnS/sulfur-containing polymer nanocomposite optical materials with high refractive index and high nanophase contents

A series of novel transparent bulk ZnS-polymer nanocomposites with high refractive index were successfully prepared via in-situ bulk polymerization in the presence of 2-mercaptoethanol (ME)-capped ZnS NPs. The polymerization mechanism combined the step-growth and free radical polymerization of different monomers of episulfide, m-xylylene diisocyanante (XDI), 2-hydroxyethyl methacrylate (HEMA) and N,N-dimethylacrylamide (DMAA). The high refractive index of episulfide compounds, including ESGMES, ESDGEBA and MPS, were synthesized and used as monomers in polymerization systems. The cured nanocomposites with 30 wt% nanoparticles show high refractive index and good transparency. The refractive index of the nanocomposites could be continuously regulated in the range from 1.59 to 1.65 by the content of ZnS NPs and the pencil hardness is round about 5H. The content of ME-ZnS NPs can affect the thermal stability, mechanical and optical properties of the resulting nanocomposites, and the relationship between them were studied by TGA, DMA, pencil hardness test, Charpy impact test.     

Preparation and characterization of high refractive index thin films of TiO2/epoxy resin nanocomposites

By using sol–gel method, amorphous titania was introduced into epoxy matrix to prepare a series of high refractive index TiO₂/epoxy resin nanocomposite films. To increase the refractive index of the hybrid films, triethoxysilane‐capped trimercaptothioethylamine (TCTMTEA), a new kind of high refractive index coupling agent was synthesized from trimercaptothioethylamine (TMTEA). In the experiment, TCTMTEA acted as the solidification agent together with TMTEA except being used as the coupling agent. The hybrid films have been characterized via FTIR, AFM, DSC, TGA, etc. The experimental results showed that the amorphous TiO₂ had been dispersed uniformly in the organic polymer matrix with the size smaller than 100 nm in each sample. More importantly, the refractive index of this kind of materials can be continuously adjusted from 1.61 to 1.797 with the content of TiO₂ increasing from 0% to 65% in mass, and the continuously adjusted refractive index is very important for the applications in optical antirefractive films. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 1631–1636, 2006     

Specific refractive index increments of segmented polyurethanes

Specific refractive index increments ν of polyester-based segmented polyurethanes in N,N-dimethyl formamide have been determined, and the quotient dν/df_d has been evaluated (where f_d is the weight fraction of hard-segment units). The results are in good agreement with the values calculated from group contributions to the molar refraction, using the Vogel or the Gladstone–Dale equations. The values calculated with the Lorenz–Lorentz equation are too low. A potential explanation of this fact is proposed. The same methods have been applied to reported ν values for polyether-based polyurethanes. An explanation is proposed for differences in dν/df_d for polyester- and polyether-based polyurethanes. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 68: 1917–1923, 1998     

Preparation and refractive index characterization of chalcogenide glasses with gradient refractive index

Infrared gradient refractive index (GRIN) lenses have great application value and potential in multispectral imaging systems. This study reports various chalcogenide axial GRIN glasses prepared using the hot-pressing diffusion method. It is worth noting that the S4–S60 GRIN sample has a difference in refractive index (RI) Δn of greater than 0.3 and a diffusion depth of about 5 mm, which is the deepest diffusion depth reported in chalcogenide glass to date. In addition, the linear portion in the profile of the GRIN sample has a RI difference of 0.15 and a thickness of 1.2 mm. The effects of the temperature, concentration difference, and diffusion time on the sample diffusion process are discussed. The dispersion properties of the GRIN samples were further calculated, providing a new option for correcting chromatic aberrations in optical systems. In addition, a method for the indirect nondestructive characterization of sample RI using the Raman intensity ratio is proposed, and the reliability of the method is verified by practical experiments, which is convenient for the subsequent measurement of the GRIN profile.     

高折光指数含硅环氧树脂的合成与性能研究

将二苯基二氯硅烷经过氢化铝锂还原为二苯基硅烷,再与4-乙烯基环氧环己烷进行硅氢加成后合成了1种新型含硅环氧树脂二[2-(3,4-环氧环己基)乙基]二苯基硅烷(EODPS)。该树脂的折光指数达到1.567,并具有较好的透明度。采用甲基六氢苯酐和乙酰丙酮铝-二苯基硅醇组合物分别对EODPS进行固化。通过红外光谱,DSC分析表征了EODPS的结构,研究了其固化活性,并对固化后产物的热稳定性、力学性能和吸水性进行了测试,且与脂环族环氧树脂CEL-2021P性能进行了比较。结果表明,与CEL-2021P相比,EODPS具有更高的热稳定性和更低的吸水率,可用于LED封装。     

Synthesis and properties of ZnS/ polyimide nanocomposite films

A series of ZnS/polyimide (PI) nanocomposite films with different ZnS contents have been successfully fabricated by incorporating ZnS nanoparticles with a diameter of 2–5 nm into polyamic acid, followed by a stepwise thermal imidization process. X‐ray photoelectron spectroscopy results confirm the successful introduction of ZnS particles into PI matrix. Transmission electron microscopy images show that the ZnS nanoparticles were uniformly dispersed in the polymer matrix without aggregation. The incorporation of ZnS nanoparticles can improve the mechanical properties and the glass transition temperature of nanocomposites, while the thermal degradation temperature of nanocomposites decreases with increasing ZnS content. Copyright © 2006 Society of Chemical Industry Society of Chemical Industry     

高折射率脂环型环氧有机硅预聚体的合成

以高含氢硅油(甲基氢硅油)为原料,在Lamoreaux催化剂作用下,先与N-烯丙基咔唑进行硅氢加成反应,再与4-乙烯基环氧环己烷反应,合成了折射率达1.577的脂环型环氧有机硅预聚体(Ep-Cz-SiO)。Ep-Cz-SiO的结构由¹H NMR和IR表征,并确定了分子中咔唑基团的含量。咔唑基团的引入显著提高了环氧有机硅预聚体的折射率。热重分析表明,所制备的带有咔唑基团的脂环族环氧有机硅预聚体的热稳定性高于含氢硅油原料。     

Fabrication of highly refractive,transparent BaTiO3/poly(methyl methacrylate) composite films with high permittivities

Incorporation of crystalline barium titanate (BT) nanoparticles into poly(methyl methacrylate) (PMMA) was carried out to prepare highly refractive polymer nanocomposite films that have transparency and high permittivities. The BT nanoparticles were prepared by hydrolysis of a barium/titanium complex alkoxide in 2‐methoxyethanol, then surface‐modified with a silane coupling agent (3‐methacryloxypropyltrimethoxysilane) to improve their affinity for PMMA. The incorporation of the surface‐modified nanoparticles into PMMA was performed up to a nanoparticle content almost equivalent to particle close‐packing state. The refractive index of the composite films increased with nanoparticle incorporation, keeping the relative transmittance normalized with PMMA film above 90%. A high refractive index of 1.82 was reached at a nanoparticle content of 53 vol% with a dielectric constant as high as 36 and a dissipation factor as low as 0.05. The results demonstrate that the crystalline BT nanoparticles are useful fillers for effectively increasing both refractive index and dielectric constant of polymer nanocomposites. Copyright © 2011 Society of Chemical Industry     

Intrinsic high refractive index polymers

As the ubiquity and complexity of optical devices grows, our technology becomes more dependent on specialized functional materials. One area of continued interest is in high refractive index polymers as lightweight, processable and inexpensive alternatives to silicon and glass. In addition to a high refractive index, optical applications require these polymers to be transparent and have a low optical dispersion. Both nanocomposite and intrinsic high refractive index polymers offer particular advantages and disadvantages. While nanocomposite high refractive index polymers have refractive indices above 1.80, the nanoparticle type, content and size can negatively affect storage stability and processability. Alternatively, intrinsic high refractive index polymers are prepared by introducing an atom or substituent with a high molar refraction into a polymer chain; the resultant polymers are easier to store, transport, tune and process. Polymers containing aromatic groups, halogens (except fluorine), phosphorus, silicon, fullerenes and organometallic moieties have all shown significant promise. Many factors can affect intrinsic high refractive index polymer performance including molecular packing, molar volume, chain flexibility and substituent content. This mini‐review summarizes the principles behind and recent developments in intrinsic high refractive index polymers. © 2014 Society of Chemical Industry     

Studies on syntheses and properties of episulfide‐type optical resins with high refractive index

A series of novel high refractive index episulfide‐type optical resins were prepared by ring‐opening copolymerization of bis(β‐epithiopropylthioethyl) sulfide (BEPTES) with episulfide derivative of diglydicyl ether of bisphenol A (ESDGEBA) and 2,4‐tolylene diisocyanate (TDI), respectively, in the presence of triethylamine as a curing catalyst. The episulfide monomers, BEPTES and ESDGEBA, were synthesized from their corresponding epoxy compounds, respectively. The cured transparent resins exhibit high refractive index (n_d > 1.63) and relatively low dispersion. The refractive index (n_d) and Abbe's number (ν_d) of the BEPTES/ESDGEBA curing system increased linearly with the weight content of BEPTES monomer in the range from 1.633 and 34.0 for the copolymer with 10 wt % of BEPTES to 1.697 and 38.1 for the homopolymer of pure BEPTES. For the BEPTES/TDI curing system, the refractive index and Abbe's number varied linearly with the molar ratio of BEPTES to TDI from 1.652 and 28.7 to 1.669 and 34.6. High glass‐transition temperatures (T_g > 130°C) of the cured BEPTES/TDI resins were observed, which indicate that the cured BEPTES/TDI resins possess a good heat resistance. The optical, physical, and thermal properties of the episulfide‐type cured optical resins were also discussed in this study. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2426–2430, 2003     

Preparation of polyurethane/hectorite,polyurethane/montmorillonite,and polyurethane/laponite nanocomposites without organic modifiers

Polyurethane (PU) nanocomposites were prepared from hectorite (HEC) and laponite without adding any organic modifier. PU‐montmorillonite nanocomposites were prepared for comparison. The structure of the composites were investigated by transmission electron microscopy, X‐ray diffraction spectroscopy, and Fourier transform infrared spectroscopy. Thermal gravimetric analysis and dynamic mechanic analysis were used for determination of the thermal and viscoelastic behaviors, respectively. Tensile tests were conducted for characterization of the mechanical properties. The results showed a 113.5% increase in the tensile strength of PU containing 7 wt % HEC compared to that of neat PU. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Rectorite/thermoplastic polyurethane nanocomposites: Preparation,characterization, and properties

A newly developed kind of layered clay, rectorite (REC), has been used to yield intercalated or exfoliated thermoplastic polyurethane rubber (TPUR) nanocomposites by melt‐processing intercalation. Because of the swollen layered structure of REC, similar to that of montmorillonite, organic rectorites (OREC) can also be obtained through ion‐exchange reaction with two different quaternary ammonium salts (QAS1, QAS2) and benzidine (QAS3). The microstructure and dispersibility of OREC layers in TPUR matrix were examined by X‐ray diffraction and transmission electron microscopy, which revealed not only that the composites with lower amounts of clay are intercalation or part exfoliation nanocomposites, but also that the mechanical properties of the composites were substantially enhanced. The maximum ultimate tensile strength for TPUR/OREC nanocomposites appeared at 2 wt % OREC loading. With increasing OREC contents, the tear strength of the composites increased significantly. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 608–614, 2004     

Preparation of low refractive index fluorinated materials for antireflection coatings

Novel low refractive index fluorinated polymers were prepared from perfluoroalkylsilane and polyethoxysiloxane by a sol‐gel technique for antireflection applications. Perfluoroalkylsilane having low refractive index fluoroalkyl groups incorporate polyethoxysiloxane by condensation of their siloxane groups to improve the adhesion and hardness of the fluorinated polymers. Syntheses and characteristics of the fluorinated polymers were investigated by the studies of FTIR, GPC, UV–vis, ellipsometry, and mechanical tests. The experimental results reveal that the refractive index and hardness of the coating using the optimal fluorinated polymer were about 1.39 and 3H, respectively, which meet the requirements in practical applications. It was also found that the fluorinated polymer made from polyethoxysiloxane had a better hardness than that made from tetraethyl orthosilicate. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

高折射率含硫环氧树脂的合成与表征

利用间接法以巯基乙醇和环氧氯丙烷 (ECH)为原料通过 3步反应得到 2 ,3 二 (2 ,3 环氧丙硫乙硫基 )丙基·2 ,3 环氧丙基硫醚型环氧树脂 (TGEBES) ,其折射率和环氧值分别达 1.5 85 0和 0 .5 3;在没有任何催化剂的条件下 ,按以三元硫醇 (BES)和ECH物质的量比为 1∶3.6、在温度为 0～ 5℃下反应 3～ 4h ,环氧化反应的产率达到84 .5 %。并利用红外光谱和核磁共振对含硫高折射率环氧树脂的结构进行了表征 ;利用高效液相色谱对TGEBES和BES的纯度进行了测定 ,结果表明TGEBES和BES纯度分别达 96 %和 97.7%以上。     

高折射率含硫环氧树脂PTETE的合成与表征

以苯硫酚、氯乙醇和环氧氯丙烷为原料,通过直接法合成高折射率苯硫基乙基-2,3环氧1丙硫醚（PTETE）环氧树脂。研究了原料配比、温度和氢氧化钠的用量等因素对产物产率的影响。得出最佳反应条件为：反应温度为0～10℃,环氧氯丙烷、MEPS与NaOH摩尔比为1．25：1：1,产率91．50％,产物的折射率1.6016。并通过FT-IR对合成的原料和产物进行表征。     

A novel mechanism of exfoliation and physical properties of PU/organoclay nanocomposites

The novel mechanism of exfoliation of silicate was investigated. Exfoliation and intercalation was achieved even at 15 wt % in the polyurethane (PU) matrix via in situ polymerization. Through using IR consumption graph of curing agent, crosslinking equation could be derived. The diffusion rate of curing agent, Isophorone diisocyanate, brought the different morphologies as well as crosslinking densities of nanocomposites. Dodecylamine, the organifier having similar hydrogen‐bonding component with Isophorone diisocyanate than octadecylamine, affected the faster diffusion of isophorone diisocyanate in hydroxyl terminated polybutadiene/organoclay composite. This phenomenon was confirmed by DSC graph, XRD, SAXS, and TEM images. The nanocomposites showed high physical properties until at 10 wt % clay. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

The relationship between refractive index and optical properties of absorbing nanoparticle

This article represents an analytical formulation for optical properties of absorbing metallic nanoparticles in visible region of electromagnetic spectrum based on Mie theory, in order to find a clear relationship between fundamental characteristics of nanoparticles with their spectral behavior and color coordinate in CIELAB color space. Calculations were performed on nanoparticles with various diameters (d = 50, 100, and 200 nm), as well as complex refractive index with different real (n = 1.5, 2.0, 2.5, and 3.0) and imaginary (k = 0.001 and 0.1) parts. Obtained results reveal that scattering phenomena in nanoparticles are strongly linked to the particle size parameter and complex index of refraction. The results indicate that the reflectance and lightness (L*) of nanoparticles increases as a result of increase in their size and real part of complex refractive index and decrease with increasing the imaginary part of complex refractive index. The CIELAB colorimetric system was used for analysis the color of nanoparticles. According to obtained results, all nanoparticles have greenish‐blue color, and undergo color change as a result of varying in their size and the complex refractive index. © 2015 Wiley Periodicals, Inc. Col Res Appl, 41, 477–483, 2016     

Preparation and properties of polypropylene/montmorillonite layered nanocomposites

Polypropylene (PP)/montmorillonite (MMT) nanocomposites have been prepared by melt intercalation using organomontmorillonite and conventional twin screw extrusion. The dispersibility of silicate layers of the montmorillonite in the composites was investigated by using X‐ray diffractometer and transmission electron microscopy (TEM). The silicate layers of montmorillonite are dispersed at the nanometer level in the PP matrix, as revealed by X‐ray and TEM results. The tensile strength of PP/MMT is not much improved compared with pure PP or conventional filled composites. However, the impact strength is greatly improved at lower content of MMT. © 2000 Society of Chemical Industry     

The effect of carbon nanotube hydrophobicity on the mechanical properties of carbon nanotube‐reinforced thermoplastic polyurethane nanocomposites

Double walled carbon nanotubes (DWNT) were functionalized by reacting methanol, dodecylamine, or octadecylamine with a toluene 2,4‐diisocyanate linker through a two‐stage reaction procedure. TGA coupled with FTIR analysis of both the decomposition products and the DWNT samples demonstrated that the functionalization procedure was successful and proceeded as expected for all samples. A preliminary investigation of the reinforcing capabilities of the functionalized DWNT in a thermoplastic polyurethane host polymer was then conducted. Tensile testing of the resultant nanocomposites demonstrated that the octadecylamine functionality provided the greatest enhancement in tensile strength and toughness. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Effects of ultrasound on the synthesis and properties of polyurethane foam/clay nanocomposites

Polyurethane foam (PUF)/clay nanocomposites were synthesized with clay modified by polymeric 4,4′‐diphenylmethane diisocyanate (PMDI) with the application of ultrasound. Transmission electron micrographs showed that the interlayer distance increased for the polyurethane (PU)/clay nanocomposites where ultrasound was applied. The results of the transmission electron microscopy and X‐ray measurements suggest that the application of ultrasound to the clay modification with PMDI improved the efficiency of the clay modification by the effective breakup of the clay agglomerates and intercalation of the silicate layers. In the mechanical tests of the PUF/clay nanocomposites, the flexural and tensile strengths of the PUF/clay nanocomposites showed the maximum value at 3.0 wt % clay content based on PMDI. These results suggest that the increases in the flexural and tensile strengths were perhaps due to the uniform dispersion of the clay by the application of ultrasound. At the same modified clay content, the fire resistance properties were increased for the PUF/clay nanocomposites with the application of ultrasound compared to the PUF/clay nanocomposites without the application of ultrasound. The cell size and thermal conductivity were decreased for the PUF/clay nanocomposites with the application of ultrasound compared to the PUF/clay nanocomposite without the application of ultrasound. Because of these results, we suggest that the smaller cell size and lower thermal conductivity of the PUF/clay nanocomposites were mainly due to the enhanced dispersion of the clay by the application of ultrasound to the mixture of PMDI and clay. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102:3764–3773, 2006