Graded‐index plastic optical fiber with high mechanical properties enabling easy network installations. II

It was shown how high mechanical strength should be provided in the high numerical aperture (NA) graded‐index plastic optical fiber (GI POF). In this newly developed GI POF, a copolymer of methyl methacrylate (MMA) and 2,2,2‐trifluoroethyl methacrylate (3FMA) was used to increase the NA. The GI POF we proposed previously was composed of a PMMA homopolymer cladding and a doped PMMA core. It was previously shown that substituting the copolymer P(MMA–3FMA) for the PMMA as the cladding material made little change in the fiber's light‐transmission characteristics. This study focused on mechanical flexibility, which is one of the most important advantages of the POF. It was found that the P(MMA–3FMA)‐clad GI POF had almost the same or superior mechanical strength in addition to the excellent light‐propagation characteristics. It was also found that such excellent mechanical properties were achieved using a small dopant concentration and optimum heat‐drawing conditions. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 410–416, 2004     

Optical and thermal properties of methyl methacrylate and pentafluorophenyl methacrylate copolymer: Design of copolymers for low-loss optical fibers for gigabit in-home communications

As a novel base material for low-loss graded index plastic optical fibers (GI POFs) in gigabit home networks, a copolymer of methyl methacrylate (MMA) and pentafluorophenyl methacrylate (PFPMA) was prepared and its thermal and optical properties were investigated. When the PFPMA content in the monomer feed was 0-50 mol%, both the glass transition temperature (T_g) and the decomposition temperature of the copolymer were higher than that for PMMA, which is the base material for many commercially available POFs. The transmittance of the copolymer was also found to be higher than that of PMMA since it has fewer C-H bonds per unit volume. As the core material of GI POFs, MMA-co-PFPMA (65/35 mol%), which had the highest T_g of 118 °C was utilized. A low-loss GI POF with an attenuation of 172-185 dB/km at the emission wavelengths of a high-speed light source (670-680 nm) was successfully obtained for the first time.     

Analysis of thermal degradation for plastic optical fibers

Attenuation loss of plastic optical fibers (POFs) gradually increases with long use at high temperatures. We separated attenuation loss of the POFs before and after heating at 150°C in air into four loss factors, and identified the main factor for attenuation loss increase as electronic transition absorption loss (α_e). The increase of α_e was caused by a thermal oxidation reaction of the core polymer in the POF. But, according to NMR and FT-IR spectra, elementary analysis, etc., hardly any reaction products were detected. We assume that the reaction products were only a small amount of the conjugated carbonyl groups. So we fabricated POFs containing model compounds with conjugated carbonyl groups, and measured their attenuation loss. The attenuation loss spectra of these POFs were similar to those of thermally degraded POFs. Consequently, a very small amount of conjugated carbonyl groups were formed by the thermal oxidation reaction of core polymer so that α_e increased to an unacceptable level.     

耐热性有机高分子的性能研究及其在塑料光纤中的应用

本文以N－环乙基马来酰亚胺（CHMI）和甲基丙烯酸甲酯（MMA）共聚得耐热性透明材料，讨论了共聚产物的透明性和玻璃化温度与CHMI含量的关系。以上述材料为基础，应用界面凝胶法制备光纤预制棒，在探讨了CHMI和PCHMI的折射率的基础上，分析并测试了光纤预制棒的折射率分布，最后拉制成塑料光纤（GI－POF）并测试了光纤的光透射窗口。     

Polymer optical fiber for near infrared use

Using the empirical simulation that we developed to estimate loss spectra of amorphous polymers, we predicted the intrinsic loss spectrum of fluorine-containing polyarylate (FPAr) that should have a small attenuation loss in the near infrared region. Loss of FPAr is smaller than that of poly (methyl methacrylate), which is a typical optical polymer used as a core material in polymer optical fiber (POF), above 720 nm. FPAr was synthesized by phase transfer catalyzed polycondensation of 2,2-bis (4-hydroxyphenyl)-1,1,1,3,3,3-hexafluoropropane with isophthaloyl dichloride. Its glass-transition temperature (T_g) by DSC is 163°C. This indicates that FPAr has higher heat resistance than polycarbonate (PC) by about 10°C. A film of 100μm thick has over 85% transmittance from 330 to 900 nm. Values from a tension test are similar to those of PC. As a result, FPAr is expected to be a good core polymer for POF, because of its high T_g, good transparency, and good flexibility. Next, the POF made of FPAr was fabricated by a melt-flow spinning method. It had larger attenuation loss than predicted. The difference from the simulation was extrinsic loss caused by the fabricating process. Therefore, when a more suitable fabricating process is developed, loss of FPAr-POF can be decreased, so that it will be applicable to optical communications in the near infrared region. © 1993 John Wiley & Sons, Inc.     

Synthesis and evaluation of fluorosilicone‐modified starch for protection of historic stone

Starch is sensitive to moisture and is weak to durability in the protection application to ancient relics. Therefore, two fluorosilicone‐modified starches are firstly prepared and evaluated for the protection of historic stones. The fluoro‐silicone copolymer grafted starch of P(VTMS/12FMA)‐g‐starch is synthesized by grafting copolymer of vinyltrimethoxysilane (VTMS) and dodecafluoroheptyl methacrylate (12FMA) onto starch. While the fluoro‐silicone starch latex of VTMS‐starch@P(MMA/BA/3FMA) is obtained by emulsion polymerization of VTMS primarily grafted‐starch (VTMS‐starch) with methyl methacrylate (MMA), butyl acrylate (BA) and 2,2,2‐trifluoroethyl methacrylate (3FMA). The grafting fluorosilicone copolymer onto starch improves obviously their hydrophobic and thermal properties. Comparatively, VTMS‐starch@P(MMA/BA/3FMA) film performs higher water contact angle (107°) and thermal stability (350–430°C) than p(VTMS/12FMA)‐g‐starch film (72°, 250–420°C) due to the migration of fluorine‐containing group onto the surface of film during the film formation. Therefore, VTMS‐starch@P(MMA/BA/3FMA) shows much better protective performance in water‐resistance, and salt/freeze‐thaw resistance for stone samples. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41650.     

Polymers for optoelectronics

This paper discusses polymers for optoelectronics, especially plastic optical fibers (POFs) for near-infrared (near-IR) use and polymeric nonlinear optical materials expected for use as switching devices. Near-IR transmissible plastic optical fibers are investigated using fluorination and deuteration for conventional polymers. Among them pentafluoro-trideutero-styrene polymer core POF has excellent transparency in the near-IR region even after water vapor absorption. Nonlinear optical polymeric materials with excellent processibilities are also investigated. The third-order nonlinear optical susceptibility of poly-aromatic vinylene thin film was measured and revealed to have a higher susceptibility than previously reported.     

Preparation of heat‐resistant gradient‐index polymer optical fiber rods based on poly(N‐isopropylmaleimide‐co‐methyl methacrylate)

Using the interfacial gel polymerization method, a heat‐resistant gradient‐index polymer optical fiber (GI POF) was developed based on the copolymer of methyl methacrylate (MMA) and N‐isopropylmaleimide (IPMI) as the matrix material and bromobenzene (BB) as dopant. The gradient distribution of IPMI in the GI POF rod was determined by element analysis. IPMI had great advantage in improving glass transition temperature (T_g) and forming a gradient‐index profile. There was a significant enhancement in the heat‐resistant property in comparison with a conventional GI POF rod. The combination of high thermal stability and easy fabrication makes the novel BB–IPMI–MMA system very suitable for heat‐resistant GI POF. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 280–283, 2003     

Climatic exposure of polymer optical fibers: Thermooxidative stability characterization by chemiluminescence

The optical transmission stability was investigated for commercially available polymer optical fibers (POFs) which were exposed to a climate of 92°C and 95% relative humidity for about 3300 h. The optical transmission stability of POFs was correlated to their thermooxidative stability. POFs possessed identical core material, poly(methyl methacrylate), but they differed in the materials used for the claddings. The optical transmission was measured online using a prototype device called multiplexer. The chemiluminescence (CL) technique was applied to characterize the thermooxidative stability and degradation of POFs. CL analysis reveals the thermooxidative degradation of bare POFs (core and cladding), predominantly of the claddings, as a result of climatic exposure. Ultraviolet–visible transmittance measurements demonstrated more changes in the claddings as compared to the cores due to degradation. The CL and optical measurements data indicated that the optical transmission stability of POFs was dependent mainly on the thermooxidative stability of the claddings and their chemical compositions. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 1593–1601, 2007     

Tribological properties of perfluoralkylethyl methacrylate-polymethyl methacrylate copolymer thin films

Perfluoroalkylethyl methacrylate and polymethyl methacrylate copolymers (FMA/MMA) were synthesized by the atom transfer radical polymerization at various FMA/MMA mole ratios. 5 wt% copolymer solutions were spun cast onto PMMA sheet substrates. The effects of monomer ratio on tribological properties were investigated in terms of the surface energy calculated from contact angles, the dynamic friction, and the wear obtained from multiple scratchings. There is a range of optimum FMA/MMA ratios between (1–5)×10⁻³ in which we attain a minimum dynamic friction. The results obtained are discussed in terms of connections between friction, surface tension, and wear mechanisms.     

Surface properties and chain structure of fluorinated acrylate copolymers prepared by emulsion polymerization

The fluorinated copolymer poly (MMA–co–FMA), composed of methyl methacrylate (MMA) and 2-perfluorooctylethyl methacrylate (FMA), was prepared by emulsion polymerization using a pre-emulsified monomer addition process. The results showed that the contact angle of water on its solvent-borne film increased dramatically and reached 118o when the FMA content in the copolymer was only 0.65 mol%, approaching that of poly(2-perfluorooctylethyl methacrylate) homopolymer. Unlike the copolymer prepared by solution polymerization, X-ray photoelectron spectroscopy (XPS), and sum frequency generation (SFG) vibrational spectroscopy analysis results indicated that the fluorinated moieties in this polymer were very easily segregated at the surface of the film. The interfacial structure and properties of this polymer in solution were investigated using SFG, surface tension, and dynamic laser light scattering (DLS). It was found that emulsion polymerization produced a chain structure of the fluorinated copolymer similar to that of FMA capped PMMA, thereby providing a possible way to produce fluorinated end-capped polymers using a popular polymerization method.     

Aging behavior of polymer optical fibers: Degradation characterization by FTIR

The optical transmission loss behavior was investigated for commercially available poly(methyl methacrylate) (PMMA) based polymer optical fibers (POFs). POFs were exposed to various climates of temperature and humidity. Optical transmission measurements using multiplexer (a prototype device) reveal that POFs exhibited an early drop‐off followed by a slow decline of transmission at 100°C with low humidity and nearly 100% loss of transmission at the early stages of exposure at 92°C with 95% relative humidity (RH) and at 120°C with low humidity. Fourier transform infrared (FTIR) and gel permeation chromatography (GPC) analysis data show no significant molecular changes in the PMMA core after climatic exposures. However, the attenuated total reflection (ATR)–FTIR data shows a few molecular changes in claddings due to degradation. Scanning electron microscopy (SEM) data illustrate the shrinkage and folding structure in claddings. The loss of the optical transmission at the early (initial) stages of exposure is attributed to the physical changes (like thermal expansion), and the same at the later stages mainly to chemical changes (e.g., oxidative degradation). The experiments conducted here show that the POFs optical transmission stability is strongly dependent on the chemical composition of claddings. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 860–870, 2007     

塑料光导纤维芯材聚合物耐热性能研究

根据塑料光导纤维芯材聚甲基丙烯酸甲酯的结构和耐热性的关系，从（甲基）丙烯酸酯系中，优选出合适的单体与甲基丙烯酸甲酯共聚，得到了几种二元和三元共聚物。用热重分析及差热分析实验方法，测试了几种共聚物的热氧降解温度（Ｔｄ）及玻璃化温度（Ｔｇ）。结果表明，分别以甲基丙烯酸环己酯、甲基丙烯酸为第Ⅱ共聚单体，以丙烯酸甲酯为第Ⅲ共聚单体，合成的三元共聚物，耐热性比均聚物有明显改善。以丙烯酸环己酯为第Ⅱ共聚单体，合成的二元共聚物的Ｔｄ有显著提高，Ｔｇ略有下降     

Effects of composition and plastifier on the light scattering of polymer glasses and properties of polymeric optical fibers made from styrene-methyl methacrylate copolymers

High optical purity polystyrene (PS), poly(methyl methacrylate) (PMMA) and styrene-methyl methacrylate statistical copolymers (S-MMA) were prepared. Light scattering measured on polymeric glasses depends on the chemical composition of the polymer and on the refractive index of the plastifier added. An isorefractive plastifier reduces considerably the scattering values for the copolymers S-MMA, while having no significant effect on the scattering of PMMA. A plastifier with a refractive index different from that of the polymer raises distinctly the light scattering values in all cases. It has been shown that the isorefractive plastifier has a favourable effect on attenuation loss of polymeric optical fibers (POF) obtained from the copolymer S-MMA 2/1.     

Amplified spontaneous emission of Eu(DBM)3Phen doped step‐index polymer optical fiber by end‐pumping with a YAG

Eu(DBM)₃Phen doped poly(methyl methacrylate) core step‐index polymer optical fiber (SI POF) has been fabricated and related properties of the doping material were discussed. Amplified spontaneous emission (ASE) at 613 nm of a SI POF with 40 cm length has been observed at ambient temperature by end‐pumping with a YAG at 355 nm. The threshold of the absorbed pump power for the onset of ASE is about 0.01 mJ. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 912–916, 2005     

热老化对PMMA塑料光纤损耗的影响

主要研究了热老化对PMMA塑料光纤损耗的影响及其影响机理.发现热物理老化减少了PMMA聚合物中的局部取向,使其形成少量的半结晶或结晶区,增加了其散射损耗;而热化学老化导致PMMA聚合物的氧化降解,严重增加了其在短波长的电子转移吸收损耗.     

Preparation and photocatalytic activity of zinc sulfide/polymer nanocomposites

ZnS nanoparticles were prepared on the surface of polyacrylonitrile (PAN) and methyl methacrylate (MMA)/butyl methacrylate (BMA)/acrylic acid (AA) copolymer nanofibers. The MMA–BMA–AA copolymer was synthesized by bulk radical polymerization using 2,2′‐azobisisobutyronitrile as the initiator. The PAN and MMA–BMA–AA copolymer nanofibers were prepared by electrospinning. Zinc ions were introduced onto the surface of the nanofibers by coordination with the carboxyl of AA. Then, sulfide ions were added to react with zinc ions to form ZnS nanoparticles. The average diameter of the nanofibers was about 300 nm, and the diameter of the ZnS nanoparticles was about 10 nm. The band position of the photoluminescence spectrum of the ZnS/PAN and MMA–BMA–AA nanocomposites had an 80‐nm blueshift in comparison with that of the corresponding bulk ZnS sample. The ZnS/PAN and MMA–BMA–AA nanocomposites had high photocatalytic activity for the degradation of phenol under ultraviolet irradiation; the photocatalytic activity changed indistinctively after it was used repeatedly (6 times). The nanofibers of PAN and MMA–BMA–AA not only dispersed but also stabilized the ZnS nanoparticles. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Preparation and properties of core–shell nanosilica/poly(methyl methacrylate–butyl acrylate–2,2,2‐trifluoroethyl methacrylate) latex

A core–shell nanosilica (nano‐SiO₂)/fluorinated acrylic copolymer latex, where nano‐SiO₂ served as the core and a copolymer of butyl acrylate, methyl methacrylate, and 2,2,2‐trifluoroethyl methacrylate (TFEMA) served as the shell, was synthesized in this study by seed emulsion polymerization. The compatibility between the core and shell was enhanced by the introduction of vinyl trimethoxysilane on the surface of nano‐SiO₂. The morphology and particle size of the nano‐SiO₂/poly(methyl methacrylate–butyl acrylate–2,2,2‐trifluoroethyl methacrylate) [P(MMA–BA–TFEMA)] core–shell latex were characterized by transmission electron microscopy. The properties and surface energy of films formed by the nano‐SiO₂/P(MMA–BA–TFEMA) latex were analyzed by Fourier transform infrared spectroscopy, differential scanning calorimetry, thermogravimetric analysis, scanning electron microscopy/energy‐dispersive X‐ray spectroscopy, and static contact angle measurement. The analyzed results indicate that the nano‐SiO₂/P(MMA–BA–TFEMA) latex presented uniform spherical core–shell particles about 45 nm in diameter. Favorable characteristics in the latex film and the lowest surface energy were obtained with 30 wt % TFEMA; this was due to the optimal migration of fluorine to the surface during film formation. The mechanical properties of the films were significantly improved by 1.0–1.5 wt % modified nano‐SiO₂. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Preparation and properties of hydrophobic MMA floor coatings based on fluorine-containing methacrylic ester copolymers

In this article, fluorine-containing methacrylic ester copolymers were successfully synthesized by a two-stage suspension polymerization and applied in manufacturing hydrophobic methyl methacrylate (MMA) floor coatings. The copolymer composition was characterized by Fourier transform infrared spectroscopy and proton nuclear magnetic resonance (¹H-NMR) spectroscopy. In addition, the mass fractions of 2-(perfluoroalkyl)ethyl methacrylate (FMA) incorporated in the copolymers were calculated according to the relative intensity of characteristic peaks in the ¹H-NMR spectrum. The prepared hydrophobic MMA floor coatings were analyzed for their coating properties such as viscosity, pot life, dry time, hardness, abrasion resistance, impact resistance, tensile strength, chemical resistance, and contact angle. Accordingly, the influence of the copolymer molecular weight and that of the incorporated amount of FMA in the copolymers were studied. Results show that coatings prepared using the copolymers with a molecular weight of 52,000 exhibit excellent comprehensive properties. Moreover, the contact angle of the coating films prepared increases as the incorporated amount of FMA increases, reaching the maximum value of 103° for 13%.     

Characterization of multiplets in a Nd3+‐doped polymer optical fiber with low ion concentration

A new model is established to infer a ratio of multipleted ions to the total ions (ρ) based on rate equations of ionic transferring between excited and unexcited states, which is designed for rare earth containing polymer optical fiber (POF) with low ion concentration ranging from 30 to 200 ppm. A step‐index (SI) Nd³⁺‐doped POF was made from a preform which was prepared by using bulk polymerization of methyl methacrylate (MMA) with a certain amount of neodymium octanoate (NOA) as a dopant, 2,2‐azoisobutyronitrile (AIBN) as an initiator, and n‐butyl mercaptan as a chain‐transfer agent. The measurement of transmission at 810 nm of the Nd³⁺‐doped POF was made by fitting experimental data and by using the theoretical model, the values of ρ at different Nd³⁺ concentration could be obtained. The result showed that the ratio is 0.03, 0.08, and 0.3 for Nd³⁺‐doped POF at Nd³⁺ concentrations of 70, 100, and 200 ppm, respectively. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 2033–2040, 2002