Kinetics analysis and physical properties of photocured silicate-based thiol-ene nanocomposites: The effects of vinyl POSS ene on the polymerization kinetics and physical properties of thiol-triallyl ether networks

The kinetics and thermal/physical properties of the trithiol-TAE (triallyl ether) system were measured with respect to increasing polyoligomeric silsesquioxane (POSS) concentrations in order to understand how the presence of POSS nanoparticles affects network formation at low loadings. Vinyl POSS monomer (vPOSS-Bu₄) with both vinyl and carboxylate pendant groups was synthesized via a thermally initiated, free-radical reaction to improve the compatibility of the inorganic particles with the trithiol and triallyl ether comomoners. Chemically modified vPOSS-Bu₄ particles were incorporated into the trithiol-TAE polymer networks by a thiol-ene free-radical photopolymerization at molar concentrations of 0, 1, and 5 ene mol%. The polymerization rates were analyzed using real-time FTIR and photo-DSC. The polymerization rates showed no significant changes with increasing vPOSS-Bu₄ concentration. Thermal analyses of the films by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) demonstrated that thermal stability improves without affecting T _g as the POSS concentration increased. Additionally, scratch resistance increased and flame spread decreased markedly with increasing POSS concentration for concentrations up to 5 mol% vPOSS-Bu₄.     

Preparation and characterization of poly(methyl methacrylate) nanocomposites containing octavinyl polyhedral oligomeric silsesquioxane

A series of poly(methyl methacrylate) (PMMA) containing octavinyl-polyhedral oligomeric silsesquioxane (OV-POSS) nanocomposites were synthesized by solution polymerization. The products were characterized by FTIR, ¹H NMR, GPC, TEM, DSC and TGA. The actual contents of OV-POSS in the obtained products and the reaction degree of the vinyl groups in the POSS were calculated on the basis of FTIR, TGA and ¹H NMR data respectively. The DSC and TGA results indicate that the incorporation of POSS molecules could improve the thermal properties of PMMA nanocomposites significantly. The glass transition temperature (T_g) and thermal decomposition temperature (T_dec1) of the nanocomposite with 12.27 wt % of OV-POSS were increased by 23 °C and 93 °C correspondingly. In our experiment, the improved thermal properties were largely attributed to the nanoreinforcement effect of POSS cages and the formation of star-shaped structures with cubic silsesquioxane core.     

Synthesis and characterization of UV-cured epoxy acrylate/POSS nanocomposites

In this study, epoxy acrylate (EA)/vinyl-polyhedral oligomeric silsesquioxane (POSS) nanocomposites were prepared through in situ polymerization and by UV-curing technique. The vinyl-POSS monomers were added to EA matrix by physically blending at loadings between 0 wt.% and 15 wt.%. The microstructure of the EA/vinyl-POSS composites was studied by X-ray diffraction (XRD) measurements, and the result indicated that the separate POSS domains were present in EA/POSS composites. Aggregates were observed in the nanocomposites by SEM and the EDS results indicated that there were vinyl-POSS molecules existing in the EA matrix. TEM images further proved there were both POSS aggregates and monomers dispersed in the EA matrix. The kinetics of the photopolymerization was investigated by real time FTIR spectroscopy. The DSC analysis showed that the increasing POSS content caused a decrease on the composite's glass transition temperature. TGA measures confirmed that the degradation mechanism of EA was not affected by POSS and the nanocomposites thermal stability was slightly improved with the increasing of POSS loadings. It can be seen that the degradation rate slowed down with the increasing of POSS content and the 50% mass loss temperature of EA/POSS hybrids all increased conspicuously relative to plain EA.     

Synthesis and characterization of AB block copolymers based on polyhedral oligomeric silsesquioxane

Well-defined diblock copolymer based on polyhedral oligomeric silsesquioxane (POSS) was synthesized by atom transfer radical polymerization (ATRP) using POSS/PMMA-Cl as a macroinitiatior. POSS/PMMA-Cl was prepared by POSS-Cl initiating the polymerization of MMA in the presence of CuCl, 2, 2, - bipyridine at 110 °C. The structure of the block copolymer had been characterized by FTIR, ¹H NMR and GPC, which all agreed well with the theoretical values. XRD measurements revealed that POSS molecules were successfully monodispered in the hybrid composite.     

Thermal study on phenyl,hepta isobutyl‐polyhedral oligomeric silsesquioxane/polystyrene nanocomposites

A comparative study concerning the thermal stability of polystyrene (PS) and three polyhedral oligomeric silsesquioxane/polystyrene (POSS/PS) nanocomposites of formula R₇R′(SiO_1.5)₈/PS (where R = isobutyl and R′ = phenyl), at various (3, 5, and 10%) POSS concentration was carried out in both inert (flowing nitrogen) and oxidative (static air) atmospheres. Nanocomposites were synthesized by in situ polymerization of styrene in the presence of POSS and the experimental filler concentration in the obtained compounds, determined by ¹H NMR spectroscopy, was in all cases slightly higher than that in the reactant mixtures. Inherent viscosity (η_inh) determinations indicated that the average molar mass of polymer in the nanocomposites was practically the same than neat PS and were in agreement with calorimetric glass transition temperature (T_g) measurements. The temperature at 5% mass loss (T_5%) and the activation energy (E_a) of degradation process of synthesized nanocomposites were determined and compared with each other and with those of unfilled PS. On the basis of the results from thermal and IR spectroscopy characterizations, nanocomposite with 5% of molecular filler appears the most thermally stable. The results were also compared with literature data on similar PS‐based nanocomposites. POLYM. COMPOS., 2013 © 2013 Society of Plastics Engineers     

Preparation and structure of poly(vinyl alcohol)–poly(vinyl acetate) composite porous membrane

The preparation of poly(vinyl alcohol) (PVA)–poly(vinyl acetate) (PVAc) composite porous membrane was investigated by extracting PVAc with solvent from films of PVAc lattices which were obtained by the emulsion polymerization of vinyl acetate (VAc) in the presence of PVA. The formation of the porous membrane depended upon whether or not PVAc in the latex film was easily extracted with solvent. In the case of using hydrogen peroxide (HPO)–tartaric acid (TA) as an initiator, in the film of the latex which was produced from the batch method in which all ingredients of the batch were put into the reaction vessel before starting polymerization, PVAc could be extracted over 90% of total PVAc with common organic solvents. In the film of the latex which was produced from the dropwise addition method of VAc and initiator, the PVAc extraction was about 20-30%. On the other hand, in the case of using ammonium persulfate as an initiator, the desired porous membrane was not obtained. The structure of the porous membrane obtained from the latex of the batch method by using HPO—TA consisted of spherical cells which were made up of PVA and grafted PVAc or insoluble PVAc like microgels, which were not extracted with organic solvent and were connected by small pores. The PVA—PVAc composite porous membrane is permeated by n-hexane with 5.58 × 10² mL/cm²·s at 0.5 kg/cm², by benzene with only 1.33 × 10^?3mL/cm²·s even at 60 kg/cm².     

POSS related polymer nanocomposites

This review describes the syntheses of polyhedral oligomeric silsesquioxane (T₈-POSS) compounds, the miscibility of POSS derivatives and polymers, the preparation of both multifunctional and monofunctional monomers and polymers containing POSS including styryl-POSS, methacrylate-POSS, norbornyl-POSS, vinyl-POSS, epoxy-POSS, phenolic-POSS, benzoxazine-POSS, amine-POSS, and hydroxyl-POSS. The thermal, dynamic mechanical, electrical, and surface properties of POSS-related polymeric nanocomposites prepared from both monofunctional and multifunctional POSS monomers are discussed. In addition, we describe the applications of several high-performance POSS nanocomposites in such systems as light emitting diodes, liquid crystals, photo-resist materials, low-dielectric constant materials, self-assembled block copolymers, and nanoparticles.     

Characterization of poly(vinyl pyrrolidone‐co‐isobutylstyryl polyhedral oligomeric silsesquioxane) nanocomposites

Poly(vinyl pyrrolidone‐co‐isobutyl styryl polyhedral oligomeric silsesquioxane)s (PVP–POSS) were synthesized by one‐step polymerization and characterized using FTIR, high‐resolution ¹H‐NMR, solid‐state ¹³C‐NMR, ²⁹Si‐NMR, GPC, and DSC. The POSS content can be controlled by varying the POSS feed ratio. The T_g of the PVP–POSS hybrid is influenced by three main factors: (1) a diluent role of the POSS in reducing the self‐association of the PVP; (2) a strong interaction between the POSS siloxane and the PVP carbonyl, and (3) physical aggregation of nanosized POSS. At a relatively low POSS content, the role as diluent dominates, resulting in a decrease in T_g. At a relatively high POSS content, the last two factors dominate and result in T_g increase of the PVP–POSS hybrid. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 2208–2215, 2004     

Poly(vinyl pyrrolidone‐co‐octavinyl polyhedral oligomeric silsesquioxane) hybrid nanocomposites: Preparation,thermal properties,and Tg improvement mechanism

A series of poly(vinyl pyrrolidone‐co‐octavinyl polyhedral oligomeric silsesquioxanes) (PVP‐POSS) organic–inorganic hybrid nanocomposites containing different percentages of POSS were prepared via free radical polymerization and characterized by FTIR, high‐resolution ¹H‐NMR, solid‐state ²⁹Si‐NMR, GPC, DSC, and TGA. POSS contents in these nanocomposites can be effectively controlled by varying the POSS feed ratios which can be accurately quantified by FTIR curve calibration. On the basis of ²⁹Si‐NMR spectra, average numbers of reacted vinyl groups of each octavinyl‐POSS macromer are calculated to be 5–7, which depends on POSS feed ratios. Both GPC and DSC results indicate that these nanocomposites display network structure and the degree of crosslinking increases with the increase of the POSS content. The incorporation of POSS into PVP significantly improves their thermal properties (T_g and T_dec) primarily due to crosslinking structure and dipole–dipole interaction between POSS cores and PVP carbonyl groups. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

The synthesis and characterization of polystyrene/magnetic polyhedral oligomeric silsesquioxane (POSS) nanocomposites

Fc-CHCH-C₆H₆-(C₅H₉)₇Si₈O₁₂ (POSS1, Fc: ferrocene) which contain both metal and CC double bond was firstly synthesized by Wittig reaction. The chemical structure of POSS1 was characterized by FTIR, ¹H, ¹³C and ²⁹Si NMR, mass spectrometry and elemental analysis, and the magnetic property of POSS1 have also been studied. Polystyrene composites containing inorganic-organic hybrid polyhedral oligomeric silsesquioxane (POSS1) were prepared by bulk free radical polymerization. XRD and TEM studies indicate that POSS1 is completely dispersed at molecular level in PS matrix when 1 wt% POSS1 is introduced, while some POSS1-rich nanoparticals are present when content of POSS1 is beyond 3 wt%. GPC results show that molecular weight of the PS/POSS1 nanocomposites are increased with addition of POSS1. TGA and TMA data show the thermal stabilities of PS/POSS1 nanocomposites have been improved compared to neat PS. The PS/POSS1 nanocomposites also display higher glass transition temperatures (T_g) in comparison with neat PS. Viscoelastic properties of PS/POSS1 nanocomposites were investigated by DMTA. The results show the storage modulus (E′) values (temperature>T_g) and the loss factor peak values of the PS/POSS1 nanocomposites are higher than that of neat PS. Mechanical properties of the PS/POSS1 nanocomposites are improved compared to the neat PS.     

Nanocomposites based on copolymers of fluorinated imide and polyhedral oligomeric silsesquioxane macromonomer: microstructure and morphology studies

Towards the development of copolymeric nanocomposites, N‐3(trifluoromethyl)phenyl‐7‐oxanorbornene‐5,6‐dicarboximide (TFI) monomer and a macromonomer of polyhedral oligomeric silsesquioxane (POSS) were synthesized. Ring‐opening metathesis polymerization to copolymerization of specified proportions of the two co‐monomers was carried out. All the monomers and polymers were characterized using Fourier transform IR analysis and ¹H and ²⁹Si NMR. Gel permeation chromatography shows that copolymeric nanocomposites have a lower average molar mass than a homopolymer of TFI (HTFI). TGA shows that the thermal stability of the copolymer is inversely proportional to the proportion of POSS units. DSC studies have demonstrated that the glass transition temperature (T_g) of a nanocomposite possessing 25 wt% POSS is at a higher temperature (180 °C) than that of HTFI (175 °C). Transmission electron microscopy and AFM images of copolymers are consistent with the self‐assembled spherical aggregation of POSS units, while X‐ray diffraction studies have confirmed the homogeneous dispersion of the same units within the nanocomposites. © 2012 Society of Chemical Industry     

Synthesis of core-shell particles by batch emulsion polymerization of styrene and octavinyl polyhedral oligomeric silsesquioxane

A new composite OVPOSS-PS was prepared by batch emulsion polymerization initiated by potassium persulfate. The structure of OVPOSS-PS composite was well characterized by FTIR, ¹H NMR, ²⁹Si NMR and XRD. The results indicated that OVPOSS could be incorporated into the PS matrix by the polymerization. TEM image shown that the composite particles were in regular shape with a uniform size and have a core-shell structure. Results of XRD revealed that POSS was well dispersed in the composites. The thermal properties were investigated by DSC and TGA. The data indicated that the incorporation of POSS can apparently improve the thermal stability of PS.     

Synthesis, characterization, and properties of chain terminated polyhedral oligomeric silsesquioxane-functionalized perfluorocyclobutyl aryl ether copolymers

A new class of perfluorocyclobutyl (PFCB) polymers covalently functionalized with polyhedral oligomeric silsesquioxane (POSS) is presented. Three discreetly functionalized POSS monomers possessing thermally reactive trifluorovinyl aryl ether (TFVE) were prepared in good yields. The POSS TFVE monomers were prepared by initial corner-capping of cyclopentyl (-C₅H₉), iso-butyl (-CH₂CH(CH₃)₂), or trifluoropropyl (-CH₂CH₂CF₃) functionalized POSS trisilanols with acetoxyethyltrichlorosilane followed by sequential acid-catalyzed deprotection and coupling with 4-(trifluorovinyloxy)benzoic acid. TFVE-functionalized POSS monomers were thermally polymerized with 4,4′-bis(4-trifluorovinyloxy)biphenyl or 2,2-bis(4-trifluorovinyloxybiphenyl)-1,1,1,3,3,3-hexafluoropropane monomers via a condensate-free, [2 + 2] step-growth polymerization. The polymerization afforded solution processable PFCB polymers with POSS macromer installed on the polymer chain ends. POSS monomers and their corresponding copolymers were characterized by ¹H, ¹³C, ¹⁹F, and ²⁹Si NMR, GPC, ATR-FTIR, and elemental combustion analysis. GPC trace analysis showed agreeable number-average molecular weight for various weight percent of cyclopentyl or iso-butyl and trifluoropropyl chain terminated POSS PFCB copolymers. DSC analysis showed the introduction of increasing POSS weight percent in the endcapped PFCB copolymers lowers the glass transition temperatures as high as 31 °C. On the other hand, the trifluoropropyl POSS endcapped PFCB polymer glass transition temperature was unaffected when copolymerized with the more fluorinated 2,2-bis(4-trifluorovinyloxybiphenyl)-1,1,1,3,3,3-hexafluoropropane monomer. TGA analysis of POSS PFCB copolymers showed step-wise decomposition of copolymers resulting from the initial degradation of the POSS cages at 297-355 °C in nitrogen and air which was confirmed by pyrolysis coupled with GC-MS. This initial weight loss was proportional to the weight percent of POSS incorporated into the polymer. The balance of decomposition was observed at 450-563 °C in nitrogen and air which is higher than the PFCB homopolymers in most cases. Polymer surface characterization was performed on spin cast transparent, flexible films. These composite films exhibited good POSS dispersion within the matrix PFCB polymer as was shown by TEM analysis.     

Preparation of high molecular weight poly(vinyl alcohol) with high yield by emulsion polymerization of vinyl acetate using 2,2′‐azobis(2‐amidinopropane) dihydrochloride

To prepare high molecular weight (HMW) poly(vinyl acetate) (PVAc) with high yield and high linearity as a precursor of HMW poly(vinyl alcohol) (PVA), vinyl acetate (VAc) was emulsion polymerized using, azo initiator, 2,2′‐azobis(2‐amidinopropane) dihydrochloride (AAPH). This was compared with the polymerization using potassium peroxodisulfate (KPS) as an initiator at various polymerization conditions. PVA, having a maximum number average degree of polymerization (P_n) of 3500 was obtained by the saponification of PVAc with P_n of 13,000–14,000, degree of branching (DB) for the acetyl group of about 3.4–3.5, and a maximum conversion of VAc into PVAc of 95%, which was polymerized by AAPH. These numerical values were superior compared with 14,500–15,000 of P_n of PVAc, obtained by KPS, and 3100 of maximum P_n of resulting PVA, DB of about 3.7–3.8, and maximum conversion of 90%. From the foregoing experimental results, we found that AAPH was a more efficient initiator than KPS in increasing both conversion of PVAc and molecular weight of PVA. In addition, PVAc microspheres, obtained by these emulsion polymerizations, can be converted to PVA / PVAc shell / core microspheres through a series of surface‐saponifications, maintaining their spherical morphology. Various surface morphologies, such as flat or wrinkled and swellable or nonswellable ones formed by the various molecular parameters and saponification conditions, were examined. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 2356–2362, 2004     

Influence of symmetry/asymmetry of the nanoparticles structure on the thermal stability of polyhedral oligomeric silsesquioxane/polystyrene nanocomposites

The thermal degradation of two polyhedral oligomeric silsesquioxane/polystyrene (POSS/PS) nanocomposites of formula R₈(SiO_1.5)₈ POSS/PS and R′₁R₇(SiO_1.5)₈ POSS/PS (where R′ = Phenyl and R = Cyclopentyl), at 5% of POSS concentration, was studied in both inert (flowing nitrogen) and oxidative (static air) atmospheres. Compounds were prepared by the polymerization of styrene in the presence of POSS. Degradations were carried out into a thermobalance, in the scanning mode, at various heating rates, and the obtained thermogravimetric (TG) curves were discussed and interpreted. The initial decomposition temperature (T_i), the temperature at 5% mass loss (T_5%), the glass transition temperature (T_g), and the activation energy (E_a) of degradation of nanocomposites were determined and compared with each other and with those of unfilled PS. The T_i, T_5%, and degradation E_a values of nanocomposites were higher than those of neat PS, thus indicating a better heat resistance and lower degradation rate, and then a better overall thermal stability. The use of POSS with a symmetric structure, in the synthesis of PS based nanocomposite, showed a decrease of T_g value not only in respect to asymmetric POSS/PS nanocomposite but also in respect to neat polymer, thus suggesting an influence of filler structure in the thermal properties of the materials. POLYM. COMPOS., 33:1903–1910, 2012. © 2012 Society of Plastics Engineers     

聚苯乙烯-丙烯酸丁酯/八异辛基倍半硅氧烷复合乳液的制备及稳定性研究

用细乳液聚合方法制备了聚苯乙烯-丙烯酸丁酯/八异辛基倍半硅氧烷复合乳液(PS t-BA/PO SS),探讨了八异辛基倍半硅氧烷在乳液中的含量对复合乳胶粒的形态、平均粒径及分布以及乳液稳定性的影响。结果表明复合乳胶粒子平均粒径为70~100nm,PO SS的含量对乳胶粒的形态和粒径分布有明显的影响,复合乳液具有良好的稀释稳定性和离心稳定性。     

Permeation characteristics of poly(vinyl alcohol)–poly(vinyl acetate) composite porous membranes

Poly(vinyl alcohol) (PVAc) composite porous membrane has been prepared from PVAc latex film by extraction with acetone. The PVAc latex was prepared by emulsion polymerization of vinyl acetate in the presence of PVA, employing the hydrogen peroxide–tartaric acid systemm as an initiator. The extraction degree of PVAc could be controlled in a wide range by changing the addition method of the initiator, and, acoordingly, PVA–PVAc omposite porous membranes which had variosu void volumes were obtained. The maximum void volume attained was ca. 90%. Permation characteristics of organic solvents wre investigated on the membranes whose extraction degrees were 95.6% and 80.7%. Thge feeds were benzene, n-hexane, cyclohexane, and their mixtures. neither swelling nor shrinkage in tje appearance size of the while benzene hardly permeated even at 20 kg/cm². The grafted PVAc in the mebrane was removed or converted into grafted PVA by treatment with sodium methylate, and then the depression of benzene permeation was lost. The grafted PVAc was suggested to be localizd on the cell wall and was found to function as a valve which closes with nenzene or a good solvent for PVAc and opens with n-haxane or a poor solvent for PVAc.     

Preparation of high‐molecular‐weight poly(vinyl alcohol) with high yield by solution polymerization of vinyl acetate in methanol using 4,4′‐azobis(4‐cyanovaleric acid)

Vinyl acetate (VAc) was solution‐polymerized at 40°C and 50°C using 4,4′‐azobis(4‐cyanovaleric acid) (ACVA) as an initiator and methanol as a solvent, and effects of polymerization temperature and initiator concentration were investigated in terms of conversion of VAc into poly (vinyl acetate) (PVAc), degree of branching (DB) for acetyl group of PVAc, and molecular weights of PVAc and resulting poly(vinyl alcohol) (PVA) obtained by saponifying with sodium hydroxide. Slower polymerization rate by adopting ACVA and lower viscosity by methanol proved to be efficient in obtaining linear high‐molecular‐weight (HMW) PVAc with high conversion and HMW PVA. PVA having maximum number–average degree of polymerization (P_n) of 4300 could be prepared by the saponification of PVAc having maximum P_n of 7900 polymerized using ACVA concentration of 2 × 10^?5 mol/mol of VAc at 40°C. Moreover, low DB of below 1 could be obtained in ACVA system, nevertheless of general polymerization temperatures of 40°C and 50°C. This suggests an easy way for producing HMW PVA with high yield by conventional solution polymerization without using special methods such as low‐temperature cooling or irradiation. © 2006 Wiley Periodicals, Inc. J Appl PolymSci 102: 4831–4834, 2006     

Preparation and thermal property of hybrid nanocomposites by free radical copolymerization of styrene with octavinyl polyhedral oligomeric silsesquioxane

The poly(styrene‐co‐octavinyl‐polyhedral oligomeric silsesquioxane) (PS–POSS) organic–inorganic hybrid nanocomposites containing various percent of POSS were prepared via one‐step free radical polymerization and characterized by FTIR, high‐resolution ¹H NMR, ²⁹Si NMR, GPC, DSC, and TGA technologies. The POSS contents in these nanocomposites were determined using FTIR calibration curve. The result shows that the POSS contents in nanocomposites can be tailored by varying the POSS feed ratios. On the basis of the POSS contents in the nanocomposites and the ¹H NMR spectra, the number of reacted vinyl groups of each octavinyl‐POSS macromonomer were calculated to be 6–8. DSC and TGA measurements indicate that the incorporation of POSS into PS homopolymer can apparently improve the thermal properties of the polymeric materials. The dramatic T_g and T_dec increases are mainly due to the formation of star and low cross‐linking structure of the nanocomposites, where POSS cores behave as the joint points and hinder the motion and degradation of the polymeric chains. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Thermal and morphological properties of high‐density polyethylene/ethylene–vinyl acetate copolymer composites with polyhedral oligomeric silsesquioxane nanostructure

The demand for improved properties of common polymers keeps increasing, and several new approaches have been investigated. In the study reported here, composites with a polymer matrix comprising a blend of high‐density polyethylene with ethylene–vinyl acetate copolymer (EVA), and with polyhedral oligomeric silsesquioxane (POSS) as a nanostructure, were processed and characterized in terms of their thermal and morphological properties. For the preparation of the composites, the concentrations of the blend components (0, 50 and 100 wt%) and of the POSS (0, 1 and 5 wt%) were varied. X‐ray diffraction results indicated that the presence of EVA in the composites led to the appearance of crystalline domains at lower POSS concentrations. Transmission and scanning electron microscopy showed that samples with 1 wt% of POSS had a homogeneous distribution in the polymer matrix with average dimensions of ca 150 nm. However, the formation of aggregates occurred in samples with 5 wt% of POSS. Differential scanning calorimetry and thermogravimetic analyses indicated that the POSS did not affect the melt and degradation temperatures of the polymer matrix. POSS underwent aggregation at higher concentrations during the composite processing, indicating a solubility limit of around 1 wt%. The presence of EVA in the composite favors POSS aggregation due to an increase in the polarity of the polymer matrix. Copyright © 2009 Society of Chemical Industry