Tetramethylpolyarylate-polyarylate block copolymer: Synthesis and miscibility with polyarylate and poly(styrene-co-acrylonitrile)

Abstract

Tetramethylpolyarylate-polyarylate (TMPAr-PAr) block copolymers of various block lengths were synthesized by the coupling reaction of hydroxy-terminated TMPAr and hydroxy-terminated PAr using triphosgene. The phase behavior of these block copolymers are discussed based on the thermal properties observed by differential scanning calorimetry (DSC). The thermal properties of binary blends of these block copolymers with PAr homopolymer or poly(styrene-co-acrylonitrile) whose acrylonitrile content is 9.5 wt% (SAN 10) were observed by DSC. The compatibilizing effect of the microphase-separated TMPAr-PAr block copolymer in PAr/SAN 10 blends was observed from thermal properties and morphology.     

Spectral properties of natural and oil polluted Baltic seawater — results of measurements and modelling

Seawater in addition to natural components such as living and non-living organic matter contains also components artificially introduced into the marine environment, such as oil substances. These components, present in the surface layer of the sea, can significantly affect radiative transfer processes. Therefore, taking into account these processes in remote sensing measurements can improve assessment of the environment. To improve local seawater optical models, it is necessary to measure the luminescence properties of all components of seawater as well as the water leaving radiance values. Additionally, substances which form the surface microlayer (surfactants — surface active agents) can affect both the dynamic characteristics of the fluxes (in particular the gas exchange and marine aerosol production) as well as inherent optical properties of surface seawater. This paper contains both the results of research focused on introducing of an efficient method for identifying oils by their fluorescence spectra as well as a marine experiment on the identification of luminescent properties of surfactants — sampled in different regions of the Baltic Sea. Moreover, the aim of the presented study is to assess the impact of the oil emulsion to spectral water leaving signal. Those results are obtained both from running Monte Carlo radiative transfer code and from approximated formulas.     

Copolymer Structure and Properties of Aromatic Polysulfonamides

A series of aromatic polysulfonamides with various monomer ratios of 4,4′-diaminodiphenylsulfone (p-DDS) and 3,3′-diaminodiphenylsulfone (m-DDS) were synthesized to investigate the relationship between copolymer composition and their properties. The copolymer composition was determined from nuclear magnetic resonance (NMR). It was found that the copolymer composition of the polysulfonamides varied little from the monomer ratio; thus, similar reactivity of the two diaminodiphenylsulfones was shown by the results. From the analysis of the thermal properties of the polysulfonamides, high thermal stability of the copolymers was shown both in N₂ and air and the decomposition temperature exhibited little dependence on the copolymer composition. However, the glass transition temperatures (T_g ) decreased obviously with increasing m-DDS segments, which is helpful to improve the solubility and spinnability of these polysulfonamides.     

Phase behavior of binary blends of symmetric polystyrene-polybutadiene diblock copolymers studied using SANS

Binary blends of compositionally symmetric diblock copolymers are investigated using small-angle neutron scattering. The study focuses on the miscibility of blends of polystyrene-polybutadiene diblock copolymers as a function of chain length ratio and blend composition, and the results are related to the theoretical phase diagram put forward by M.W. Matsen (J. Chem. Phys. 103, 3268 (1995)). Three different low molar mass copolymers were blended with a high molar mass copolymer. We find very good coincidence with the theoretical phase diagram obtained. Only for blends having a chain length ratio of 0.06, theory predicts that a larger amount of short copolymers can be dissolved in the matrix of long copolymers, and vice versa. With the latter blends and volume fractions of short chains between 0.11 and 0.70, the second-order Bragg-peaks do not vanish, which indicates that the lamellae are asymmetric. Received: 9 February 1998 / Revised: 20 April 1998 / Accepted: 24 April 1998     

一种侧链共轭噻吩共聚物增强的三阶非线性光学特性

侧链共轭的聚噻吩衍生物具有拓宽的共轭程度,有望成为一类性能优良的三阶非线性光学材料.合成了一种侧链共轭的噻吩共聚物:聚 -噻吩(POTVTh-Th),该聚合物与其均聚物相比,吸收光谱发生了明显的红移,禁带宽度为1.72eV.采用Z扫描技术在800nm下用飞秒激光器研究了该聚合物溶液和薄膜的三阶非线性光学特性,结果表明该共聚物四氢呋喃溶液中的三阶非线性极化率为8.84×10^-10esu,聚合物薄膜的三阶非线性极化率为7.25×10^-9esu,分别是其 关键词： 侧链共轭 噻吩共聚物 三阶非线性极化率 非线性吸收     

Designing and Characterization of Poly(L-Lactide)/Poly(ϵ-Caprolactone) Multiblock Copolymers

A series of poly(L-lactide)/poly(?-caprolactone) (PLA/PCL) biodegradable multiblock copolymers was synthesized by a two-step process and characterized. Ring-opening polymerization was used to prepare a series of HO-PLA-PCL-PLA-OH copolymers initiated by hydroxyl-terminated PCL. Then the triblock copolymers and 1,6-hexamethylene diisocyanate (HDI) were reacted with different copolymer/HDI weight ratios. Consequently, a series of PLA/PCL multiblock copolymers with designed molecular chain structure was obtained. Gel permeation chromatography (GPC), Fourier transform infrared (FTIR) spectroscopy, and ¹H NMR were used to characterize these copolymers and the results showed that the designed PLA/PCL copolymers had been synthesized. Dynamic mechanical analysis (DMA) was applied to characterize their thermal properties. Stress–strain curves showed that a PLA/PCL copolymer with adjustable mechanical properties had been achieved.     

Preparation and Characterization of Poly(L-lactic acid)/Polybutadiene Block Copolymers

A two-step process to prepare poly(L-lactic acid) (PLLA)/polybutadiene (PB) block copolymers was studied. Melt polymerization was used to prepare poly(L-lactic acid) terminated with hydroxy groups, at the same time hydroxy-terminated polybutadiene and 1,6-hexamethylene diisocyanate were employed to synthesize isocyanate-terminated polybutadiene (ITPB). Then PLLA and ITPB were reacted with different PB/PLLA weight ratios. Consequently, a series of PLLA/PB copolymers with linear or crosslinked chains was obtained. Viscosity of the linear copolymer was measured by an Ubbelohde viscometer. Swelling characteristics and crosslink density of the crosslink copolymer were investigated. Fourier transform infrared and proton nuclear magnetic resonance were used to characterize the structure of the copolymer, and dynamic mechanical analysis (DMA) was applied to characterize its thermal properties. Mechanical property measurements showed that a toughened PLLA polymer was synthesized. Atomic force microscope was utilized to characterize its micro-morphology.     

Defining donor and acceptor strength in conjugated copolymers

ABSTRACT

The progress in efficiency of organic photovoltaic devices is largely driven by the development of new donor–acceptor (D–A) copolymers. The number of possible D–A combinations escalates rapidly with the ever-increasing number of donor and acceptor units, and the design process often involves a trial-and-error approach. We here present a computationally efficient methodology for the prediction of optical and electronic properties of D–A copolymers based on density functional theory calculations of donor- and acceptor-only homopolymers. Ten donors and eight acceptors are studied, as well as all of their 80 D–A copolymer combinations, showing absorption energies of 1.3–2.3 eV, and absorption strengths varying by up to a factor of 2.5. Focus lies on exhibited trends in frontier orbital energies, optical band gaps, and absorption intensities, as well as their relation to the molecular structure. Based on the results, we define the concept of donor and acceptor strength, and calculate this quantity for all investigated units. The light-harvesting capabilities of the 80 D–A copolymers were also assessed. This gives a valuable theoretical guideline to the design of D–A copolymers with the potential to reduce the synthesis efforts in the development of new polymers.     

Synthesis, characterization, and corrosion protection properties of poly(N-(methacryloyloxymethyl) benzotriazole-co-methyl methacrylate) on mild steel

The copolymers from different feed ratios of N-(methacryloyloxymethyl) benzotriazole (MMBT) and methyl methacrylate (MMA) has been synthesised using free radical solution polymerization technique and characterized using FT-IR and ¹³C NMR spectroscopy. The thermal stability of the polymers was studied using theremogravimetrtic analysis (TGA). The corrosion behaviors of mild steel specimens dip coated with different composition of copolymers have been evaluated by potentiodynamic polarization and electrochemical impedance spectroscopic (EIS) method. These electrochemical properties were observed in 0.1 M HCl medium. The polarization and impedance measurements showed different corrosion protection efficiency with change in composition of the copolymers. It was found that the corrosion protection properties are owing to the barrier effect of the polymer layer covered on the mild steel surfaces. However, it was observed that the copolymer obtained from 1:1 mole ratio of MMBT and MMA exhibited better protection efficiency than other combinations.     

Ellipsometry measurements of glass transition breadth in bulk films of random, block, and gradient copolymers

Bulk films of random, block and gradient copolymer systems were studied using ellipsometry to demonstrate the applicability of the numerical differentiation technique pioneered by Kawana and Jones for studying the glass transition temperature (T _g) behavior and thermal expansivities of copolymers possessing different architectures and different levels of nanoheterogeneity. In a series of styrene/n -butyl methacrylate (S/nBMA) random copolymers, T _g breadths were observed to increase from ～ 17^° C in styrene-rich cases to almost 30^° C in nBMA-rich cases, reflecting previous observations of significant nanoheterogeneity in PnBMA homopolymers. The derivative technique also revealed for the first time a substantial increase in glassy-state expansivity with increasing nBMA content in S/nBMA random copolymers, from 1.4×10^-4 K-1 in PS to 3.5×10^-4 K-1 in PnBMA. The first characterization of block copolymer T _g ’s and T _g breadths by ellipsometry is given, examining the impact of nanophase-segregated copolymer structure on ellipsometric measurements of glass transition. The results show that, while the technique is effective in detecting the two T _g ’s expected in certain block copolymer systems, the details of the glass transition can become suppressed in ellipsometry measurements of a rubbery minor phase under conditions where the matrix is glassy; meanwhile, both transitions are easily discernible by differential scanning calorimetry. Finally, broad glass transition regions were measured in gradient copolymers, yielding in some cases extraordinary T _g breadths of 69- 71^° C , factors of 4-5 larger than the T _g breadths of related homopolymers and random copolymers. Surprisingly, one gradient copolymer demonstrated a slightly narrower T _g breadth than the S/nBMA random copolymers with the highest nBMA content. This highlights the fact that nanoheterogeneity relevant to the glass transition response in selected statistical copolymers can be comparable to or exceed that observed in moderately phase-segregated gradient copolymers.     

光学窗口表面憎水改性工艺研究

海洋环境下使用的光学窗口常因海水等附着而影响其光学性能。从固体-液体界面理论入手,分析了光学窗口的表面能对海：水附着特性的影响,开发了一种外场环境下可以实施的光学窗口表面憎水改性工艺。该工艺采用一种含有氟烃基硅烷的活性物质掺杂于SiO2溶胶中,通过涂擦和低温固化方式,在光学窗口表面形成纳米憎水膜,该憎水膜可使SiO2表面能由30mJ／m^2降至5mJ／m^2以下,水接触角由47°增加至105°以上。试验研究了改性后光学窗口的盐水接触角、光学透过率及耐候性,结果表明,用于改性的憎水膜海洋环境使用寿命大于6个月。通过定期对光学表面实施憎水改性保养可以显著减少海水附着。     

Density functional theory design D-D-A type small molecule with 1.03 eV narrow band gap: effect of electron donor unit for organic photovoltaic solar cell

Six new low-band-gap copolymers of donor–donor–acceptor (D-D-A) architecture have been designed using density functional theory and time-dependent density functional theory methods in order to use them in organic photovoltaic cell (OPVC). Phenanthro[3,4-d:9,10-d′]bis([1,2,3]thiadiazole)-10,12-dicarbonitrile moiety has been used as an acceptor for all compounds. We insert benzo[1,2-b:4,5-b′]dithiophene and N,N-diphenylbenzo[1,2-b:4,5-b′]dithiophen-2-amine units as donor to complete designing of copolymers. In order to tuning the optical and electronic properties, we have modified the donor unit by substituted with amine, methoxyamine, N-methylenethiophen-2-amine, methoxy, alkoxy moieties. The band gap (E_g), HOMO and LUMO values and plots, open circuit voltage (V_OC) as well as optical properties have been analysed for designed copolymers. The optimised copolymers exhibit low-band-gap lying in the range of 1.03–2.24 eV. DPTD-6 copolymer presents the optimal properties to be used as an active layer due to its low E_g (1.03 eV) and a moderate V_OC (0.56 eV). Thus, OPVC based on this copolymer in bulk-heterojunction composites with [6,6]-phenyl-C₆₁-butyric acid methyl ester (PCBM) as an acceptor has been modelled. E_g and V_OC values of composite material DPTD-6:PCBM are found as 1.32 and 0.65 eV, respectively. A model band diagram has been established for OPVC, simulating the energy transfer between active layers.     

Critical Evaluation of Analytical Procedures for the Determination of Lead in Seawater

Abstract: This article presents a critical evaluation of the analytical procedures used for the determination of lead in seawater, which is important because lead is a good indicator of marine pollution caused by human activities. Sampling, storage, and pretreatment techniques are briefly overviewed, including the significance of systematic errors that cannot be corrected later on. The main techniques in this article are electrothermal–atomic absorption spectrometry (ET-AAS), inductively coupled plasma–mass spectrometry (ICP-MS), and voltammetry. Flame atomic absorption spectrometry (FAAS) and inductively coupled plasma–optical emission spectrometry (ICP-OES) are treated as well, although their limits of quantification are not sufficient for a determination of lead in unpolluted seawater. Even when separation and preconcentration techniques are applied, these techniques are only capable of detecting lead in polluted coastal seawater. Separation and preconcentration are actually also required for ET-AAS and ICP-MS in order to determine the lowest concentrations of lead found in unpolluted open-ocean seawater, which is still a challenge for the analytical chemist.     

几种高分子材料的域结构、分子动力学和相互作用的固体NMR研究

聚3-羟基丁酸酯(PHB)是微生物细胞在其生长的特定时期在胞内合成的具有相应生物功能的聚羟基烷酸酯类物质, 是一种具有潜在的广泛应用前景的生物可降解的高分子材料. 由于天然的PHB其较高的结晶度和较窄的温度处理范围,它在应用过程中受到较大的局限性. 人们将结构相似的单体3-羟基戊酸(HV)与3-羟基丁酸(HB)共聚形成共聚物(PHBV)以后, 显著改善了PHB的物理机械性能,譬如:冲击强度和韧性有所增加，而硬度脆性有一定程度的下降. 人们虽然在这些降解高分子材料的开发、制备和物理机械性能以及这些材料的应用等方面有很多研究，但是有关分子水平的问题并未得到系统的探索. 因此，针对这些分子基础问题(结构域特征和分子动力学等)做了一些初步的研究.  全氟磺酸树脂(Nafion)是杜邦公司生产的一种燃料电池电极薄膜材料，其较低的使用温度(<100℃)严重地限制了它的应用范围. 人们发现，当把层状硅酸盐(蒙脱土)和Nafion合成为有机无机纳米复合材料之后，在一定程度上提高了它的使用温度. 虽然这种复合材料很容易合成出来并且已经运用到了实际工业应用之中，但是这种热稳定性提高的原因却不甚清楚. 通过固体NMR等分析方法从微观相互作用方面来认识这种宏观性能改善的原因.  使用固体¹³C CP MAS、¹³C SPE MAS NMR以及XRD方法测定了PHB和两种PHBV的结晶度(X_c)，发现随着HV的引入它们的X_c 逐渐减小. 研究同时发现在测量X_c 的这几种方法中¹³C SPE MAS NMR误差较小. 实验中我们利用质子弛豫诱导谱编辑(PRISE)、质子自旋扩散(Spin-diffusion)等固体NMR技术研究了PHB以及不同含量HV的PHBV的结构域特征和相应结构域的运动性. 实验结果表明随着HV含量的增加，它们的非晶相结构域尺寸增大，晶相结构域尺寸减小，可以看出HV的引入导致PHB的结构域特征的变化是其宏观性能改善的原因.  进一步通过低分辨固体NMR测量了PHB和PHBV的变温质子弛豫时间(T₁, T_1ρ, T₂), 然后通过理论拟合获得了它们不同运动状态的分子运动相关频率(τ_c)和分子活化能(E_a)等动力学信息，研究发现随着HV含量的增加，分子运动加快，活化能减小，在分子水平上认识了HV的引入使得PHB宏观性能改善的微观原因.  通过溶胶凝胶法合成了燃料电池电极薄膜(Nafion)和层状硅酸盐(蒙脱土)纳米复合材料来提高Nafion的使用温度，FT-IR和²⁹Si MAS NMR实验结果表明在杂化材料中虽然质子化的十二烷基胺修饰的蒙脱土(MMT)的引入没有导致MMT的骨架结构发生明显变化，而且Nafion也没有插入到MMT的层间，但是TGA分析表明杂化材料中的Nafion的热稳定性比纯的Nafion高. 通过一系列固体NMR技术包括¹⁹F MAS、¹H-¹³C CP MAS NMR和¹H-¹³C HETCOR 2D NMR实验初步证实了这种材料的热稳定性的提高可能是由于MMT表面吸附的NH⁺₃与Nafion侧链上的SO^-₃之间存在较强的静电相互作用，初步可以认为这种相互作用是导致电极材料性能改善的原因.     

Thermo-Sensitivity of poly-N-isopropylacrylamide with Statistically Introduced D,L-Allylglycine Betainic Units

Abstract

Statistical copolymers of N-isopropylacrylamide containing 2.2 – 2.7?mol % D,L-allylglycine were synthesized. The sample with 2.2?mol % allylglycine and molar mass 320000?g/mol was studied using light scattering and turbidimetry while heated in water and water–salt solutions. Temperature dependencies of light scattering intensity and optical transmission as well as hydrodynamic size and composition of the scattering entities were obtained in a wide range of pH. The onset temperatures of phase separation were independent of pH; however, in the basic pH region the phase transition was widened as compared to the neutral and acid media. It was shown that a small content of allylglycine results in a different thermoresponsive behavior of the copolymer as compared with N-isopropylacrylamide homopolymer. The addition of a physiological amount of NaCl shifts the copolymer thermo-sensitivity toward lower temperatures.     

Enhancement of Luminescence in the Photolysis Of Eu(III) Poly(Acrylic Acid-co-Butyl Methacrylate) Complexes

The fluorescent and photochemical properties of Eu (III) with copolymers of acrylic acid and butyl methacrylate were investigated. It was found that photochemical behavior of Eu³⁺ complexes with copolymers is essentially different from those of Eu³ with polyacrylic acid - in the former Eu³ luminescence intensity during photolysis noticeably enhances rather than reduces. It has been found that the presence of steric hindrances and coordinatively unsaturated structures in the initial complexes with copolymer and peculiarities of the photodecomposition of macromolecular ligand favors the enhancement of the luminescence during the photolysis     

Ultrasonic degradation of poly (styrene-co-alkyl methacrylate) copolymers

The ultrasonic degradation of poly (styrene-co-methyl methacrylate) (SMMA), poly (styrene-co-ethyl methacrylate) (SEMA) and poly (styrene-co-butyl methacrylate) (SBMA) copolymers of different compositions was studied. The copolymers were synthesized and NMR spectroscopy was used to determine the composition, and the glass transition temperatures were determined by DSC. The reactivity ratios were determined by the Kelen–Tudos method and it indicated that the copolymers were random. The effect of solvent, temperature and copolymer composition on the ultrasonic degradation rate of these copolymers was investigated. A model based on continuous distribution kinetics was employed to study the degradation kinetics. The degradation rate coefficients of the copolymers decreased with an increase in the styrene content in the copolymer. At any particular copolymer composition the rate of degradation follows the order: SBMA > SEMA > SMMA. Thermogravimetric analysis (TGA) of the copolymers was carried in order to assess their thermal stability. The same order of degradation was observed for the thermal degradation of the copolymers as that observed for ultrasonic degradation.     

Interaction mechanism between copolymer inhibitor and β-dicalcium silicate surface based on molecular dynamics simulation

Copolymer inhibitor with multifunctional groups has a good effect on inhibiting the secondary reaction in the clinker leaching process for alumina production, but the inhibition mechanism of the copolymer is not clear yet. In this paper, molecular dynamics simulation was used to study the adsorption process of the copolymer inhibitor with multifunctional groups, such as acrylic acid-vinyl alcohol copolymer (PAV) and acrylic acid-hydroxypropyl acrylate copolymer (PAH), on the β-dicalcium silicate (C₂S) crystal surface, and reveal its inhibiting mechanism. Meanwhile, the polyacrylic acid (PAA) with only the carboxyl group also is simulated for comparing the inhibition effect with copolymer inhibitors. The results show that the binding energy between copolymer (PAV, PAH) and β-C₂S is greater than that of PAA with a single functional group. The order of binding energy is as follows: PAH?>?PAV?>?PAA. In aqueous solution, the water molecule can restrict the degree of deformation of polymers, increase the distance between polymers and β-C₂S and then lead to weakening of the adsorption of polymers on the crystal surface. The comprehensive and coordination effect of carboxyl and hydroxyl functional groups in PAV and PAH can strengthen the adsorption of copolymers on the β-C₂S surface. The different spatial distribution of multifunctional groups in the molecular structure has a different influence on the adsorption of the copolymer. The results can provide a theoretical basis for researching new and highly effective copolymer inhibitors with multifunctional groups.

Compared the adsorption state: The comprehensive and coordinate action of carboxyl and hydroxyl groups of the inhibitor with multifunctional groups make the inhibitor have a stronger adsorption ability on the surface of β-C₂S than that with a single functional group. The results obtained in this paper can provide a theoretical basis for the research and development of new and highly effective polymeric inhibitors with multifunctional groups.

Highlights

The interaction between copolymer and β-C₂S was investigated by MD simulation.

The binding energy order between polymers and β-C₂S is PAH?>?PAV?>?PAA.

The presence of water molecules can weaken the adsorption of the copolymer on the surface of β-C₂S.

The comprehensive and coordinate action of carboxyl and hydroxyl groups of the inhibitor with multifunctional groups make the inhibitor have a stronger adsorption ability on the surface of β-C₂S than that with a single functional group.     

Surface wetting behavior of the poly(styrene-b-isoprene-b-styrene) triblock copolymer with different chemical structures of the polyisoprene block chain

The relationship between the chemical structure of a block copolymer and its surface structure and properties is very important for the careful design of its outer surface layer. For this paper, a series of poly(styrene-b-isoprene-b-styrene) triblock copolymers (SIS), with different chemical structures in the polyisoprene block chain, were synthesized by anionic polymerization and their dynamic wetting behaviors were investigated. The dynamic contact angles of the polyisoprene homopolymer (PI) and the SIS were almost the same when the PI and the corresponding block in the SIS had similar chemical structures. The receding contact angle (θ_r) of SIS depended on the microstructure of the PI block chain, however, the advancing contact angles (θ_a) were almost the same regardless of the PI’s chemical structures. The receding contact angle (θ_r) of SIS containing 3,4-PI was far higher than that of SIS with 1,4-PI. Meanwhile, it gradually approached that of SIS with 1,4-PI as the of 3,4-PI content decreased or as the local temperature increased. Contact angle measurement is one of the most sensitive methods for providing information on the outer few angstroms of a polymer’s surface. Therefore, by designing SIS with different chemical structures in the PI block, it was confirmed that the properties and structure of the outermost layer of the SIS were controlled primarily by the PI block’s chemical structure. This demonstrates the possibility to modulate the surface structure and properties of SIS by adjusting the chemical structure of polyisoprene segment.     

Direct Fluorescence Monitoring of Coal Organic Matter Released in Seawater

Whenever immersed in seawater after a collier accident, a fossil fuel such as coal could become a source of pollution to the marine environment. To study the effect of such a contamination, four coal samples from different origins were used. A first analysis on those coals enabled us to determine the content of polycylic aromatic hydrocarbons. Seawater was then mixed with coal to study the organic matter released from coal into seawater. Fluorescence was used for its sensitivity to aromatic compounds, with the additional purpose of evaluating the relevance of using an immerse fluorescence probe to monitor water pollution. Excitation–emission matrices were recorded and the excitation–emission wavelength range corresponding to the highest fluorescence intensity was 230 nm/[370 nm; 420 nm]. The samples with coal happened to fluoresce more than the coal-free samples, the difference depending on the coal origin. The fluorescence intensity increased with coal mass, up to some limit. The particle size also influenced the fluorescence intensity, the finest particles releasing more fluorescing substances, due to their higher exchange surface. When seawater percolated through coal, the samples fluoresced highly at the beginning, and then the fluorescence intensity decreased and reached the seawater level. However, even with a 10 ns acquisition time shift, the fluorescence spectra were not specific enough to show the presence of PAHs in the samples, which were too diluted to be detected, whenever released from coal into seawater. The lifetimes of the seawater and of the coal samples were respectively 4.7 and 3.8 ns, indicating that the substances released from coal mainly consisted of short-lived fluorescing substances, such as natural humic or fulvic substances. Consequently, the presence of coal does not seem to be too detrimental to the marine environment, and a direct fluorescence probe could be used to monitor the seawater organic charge increase due to the immersion of coal in seawater.