Toluene Diisocyanate Research Articles

Theoretical analysis and evaluation of reaction routes by "three-parameter difference".

How to choose a high-efficiency, green and inherent safety synthetic route is an important issue for the development of the chemical industry. “Three-parameter difference” is a complex parameter with the calculation of Gibbs free energy, atom utilization and inherent safety index, and can be used to comprehensively evaluate the thermodynamic feasibility, greenness and safety of chemical reactions. This parameter has been proposed and established, but the reliability has not been determined. In this study, the parameter has been corrected to make it more universal. It was calculated and studied in the synthesis of dimethyl carbonate and toluene diisocyanate, separately. The results showed that the reaction pathways for synthesizing dimethyl carbonate from the gas-phase oxidative carbonylation of methanol by a one-step process, and toluene diisocyanate from dimethyl carbonate-ionic liquid hydroxylamine have obvious advantages and future research prospects. They are consistent with the existing actual research, which can prove the reliability of the “three-parameter difference”. More importantly, the parameter provides a theoretical basis and has an adequate practical guidance significance to design and evaluate a new synthesis route.

Electrostatic self-assembly desensitization of CL-20 by enhanced interface interaction

In this work, Polyquaternium-7 (M550) was utilized as the intermediate layer to strengthen the interface interaction between hexanitrohexaazaisowurtzitane (CL-20) and graphene oxide (GO), and then CL-20/M550-GO (CMG) was prepared through electrostatic self-assembly. The surface morphology and component of CMG were determined, which proved that CL-20 was covered with M550-GO. The thermal measurement showed that the coating of M550-GO can increase the transformation temperature of the crystal form of CL-20. The impact sensitivity and friction sensitivity of CMG was measured by the BAM method, and the results were 35 J and 288 N, respectively. To our best knowledge, this is the best desensitizing effect of CL-20. Meanwhile, the composite presented good compatibility with 3,3-Diazide methyl oxetane and tetrahydrofuran copolyester (PBT) and toluene diisocyanate (TDI), which indicates the potential application of this strategy in a cross-linked propellant system. Excluding the influence of the content and crystal form on the mechanical sensitivity, M550 was ensured to be responsible for the improved desensitizing effect by enhancing the interface interaction between CL-20 and GO. In brief, this work provides an effective strategy to equilibrium between safety and energy properties of the explosive.

Preparation and characterization of yellow waterborne polyurethane with 2,6-diaminoanthraquinone structure

Poly (2-methyl-1,3-propylene glycol-adipic acid) ester diol (PMA-1000), 2,2-dihydroxymethyl propionic acid (DMPA), toluene diisocyanate (TDI), 1,4-butanediol (BDO), 2,6-diaminoanthraquinone (DAAQ) were used as raw materials, triethylamine (TEA) as neutralizer, and yellow waterborne polyurethane dye (DAAQ-WPU) containing DAAQ was obtained after emulsification. The structure and properties of the product were characterized by infrared spectroscopy, fluorescence spectrophotometer, laser particle size analyzer, spectrophotometer and color fastness tester. The results show that, DAAQ anthraquinone structure is connected to the water-based polyurethane chain, DAAQ-WPU is synthesized, and its emulsion has purple fluorescence at 300–350 nm band. With the increase of DAAQ content, the particle size of DAAQ-WPU emulsion increases from 69.7 nm to 104.9 nm, the b* value of film increases from 10.4 to 45.39, and the yellow color deepens gradually. DAAQ-WPU has good color fastness to cotton cloth, and its color fastness to rubbing, water stain and soaping is 4–5 grade.

Synthesis and characterization of novel poly(urethane-amide)s with enhanced thermal stability

The aim of the present study was to design and synthesis a novel monomer to produce polyurethanes with improved thermal stability as well as good solubility. Herein, N1,N3-bis(5-hydroxynaphthalene-1-yl) isophthalamide was synthesized by the nucleophilic reaction of 5-amino-1-naphthol and isophthaloyl chloride. Afterward, the synthesized diol was reacted with various diisocyanates such as toluene diisocyanate and methylene diphenyl diisocyanate to attain novel poly(urethane-amide)s via condensation reaction. The chemical structure of the monomer and the resulting polymers were thoroughly investigated and approved via spectroscopic techniques and elemental analysis. Also, physical properties of the prepared polymers like thermal characteristics, molecular weight, solubility, and viscosity together with their structure-property relationship were evaluated. The obtained results showed improved thermal stability of the synthesized poly(urethane-amide)s compared to other common polyurethanes. Also, the results indicated that the higher the aromatic groups in the polymer chain, the higher the thermal stability and glass transition temperature. Presence of bulky naphthyl groups from another side, improve their solubility as well. The synthesized poly(urethane-amide)s with remarkable thermal stability and solubility might open up new possibilities for a wide range of applications in various industries such as transportation, aerospace, electronics, appliances, and so on.

Covestro revives plan for major MDI plant

Covestro has revived its plan to build a world-scale plant for methylene diphenyl diisocyanate (MDI), a polyurethane intermediate, in China or the US. Covestro had shelved the project, then planned for Texas, in early 2020. The firm now hopes to open the plant in 2026. It would use technology that Covestro says consumes 25% less electricity and creates 35% less CO 2 than standard MDI technology. Covestro also plans to increase its production of toluene diisocyanate—another polyurethane intermediate—in Dormagen, Germany.

Benign fabrication process of hierarchal porous polyurea microspheres with tunable pores and porosity: Their Pd immobilization and use for hexavalent chromium reduction

Developing new strategies for fabrication of porous materials with tunable morphology which have fewer environmental impacts is highly desired. Herein, conventional precipitation polymerization of polyurea (PU) synthesis is converted to interfacial polymerization via simple microfluidics and hierarchically porous and uniform PU microspheres (PPM) are prepared by the reaction of toluene diisocyanate and water, eliminating the use of toxic amines and organic solvents. The morphology and porosity of PPM are probed. The size of PPM is controlled by changing the diameter of flow channels of microfluidic device and their pore size and porosity are tuned by optimizing the polymerization conditions. Moreover, palladium (Pd) is immobilized on PPM by impregnation and subsequent reduction approach to get Pd@PPM. The hybrid composite, Pd@PPM, is used for catalytic reduction of toxic Cr6+ to benign Cr3+ by formic acid as a reductant along with sodium format as a promoter in aqueous system. Pd@PPM exhibited high catalytic activity and good stability for Cr6+ reduction and their large size with high uniformity eased their recovery to reuse them in subsequent Cr6+ reduction. Porous PU with controllable shape and morphology are rarely available. This work therefore provides new strategy to synthesis PPM with controllable porous morphology and their use as an effective support for catalysis.

Synthesis of Polyurethane Membranes Derived from Red Seaweed Biomass for Ammonia Filtration

The development of membrane technology is rapidly increasing due to its numerous advantages, including its ease of use, chemical resistant properties, reduced energy consumption, and limited need for chemical additives. Polyurethane membranes (PUM) are a particular type of membrane filter, synthesized using natural organic materials containing hydroxy (-OH) groups, which can be used for water filtration, e.g., ammonia removal. Red seaweed (Rhodophyta) has specific molecules which could be used for PUM. This study aimed to ascertain PUM synthesis from red seaweed biomass (PUM-RSB) by using toluene diisocyanate via the phase inversion method. Red seaweed biomass with a particle size of 777.3 nm was used as starting material containing abundant hydroxy groups visible in the FTIR spectrum. The PUM-RSB produced was elastic, dry, and sturdy. Thermal analysis of the membrane showed that the initial high degradation temperature was 290.71 °C, while the residue from the thermogravimetric analysis (TGA) analysis was 4.88%. The PUM-RSB section indicates the presence of cavities on the inside. The mechanical properties of the PUM-RSB have a stress value of 53.43 MPa and a nominal strain of 2.85%. In order to optimize the PUM-RSB synthesis, a Box–Behnken design of Response Surface Methodology was conducted and showed the value of RSB 0.176 g, TDI 3.000 g, and glycerin 0.200 g, resulting from the theoretical and experimental rejection factor, i.e., 31.3% and 23.9%, respectively.

Blocking and Deblocking of Diisocyanate to Synthesize Polyurethanes.

Diisocyanates, particularly toluene diisocyanate (TDI), are useful for the preparation of various polyurethanes with specific applications as leather-like materials, adhesives and insoles, etc. Blocking agents can be used for the operational simplicity and to reduce the hazards of TDI. In this paper, we reported the use of 3-(4-bromo-phenyl)-1H-pyrazole to block toluene diisocyanate (TDI). FTIR, NMR, thermogravimetric analysis, contact angle analysis and differential scanning calorimetry (DSC) were used for the characterization. The effectiveness of the blocking was confirmed by spectroscopic techniques. The DSC thermogram showed that blocked adducts deblock at 240 °C, causing the regeneration of TDI, and causing the diisocyanates to react with polyols of different molecular weights, forming polyurethanes. The characterization of the polyurethanes was performed by infrared spectroscopy, nuclear magnetic resonance spectroscopy, thermogravimetric analysis, differential scanning calorimetry and a contact angle study.

Fluoropolymer/Glycidyl Azide Polymer (GAP) Block Copolyurethane as New Energetic Binders: Synthesis, Mechanical Properties, and Thermal Performance.

In order to enhance the application performance of glycidyl azide polymer (GAP) in solid propellant, an energetic copolyurethane binder, (poly[3,3-bis(2,2,2-trifluoro-ethoxymethyl)oxetane] glycol-block-glycidylazide polymer (PBFMO-b-GAP) was synthesized using poly[3,3-bis(2,2,2-trifluoro-ethoxymethyl)oxetane] glycol (PBFMO), which was prepared from cationic polymerization with GAP as the raw material and toluene diisocyanate (TDI) as the coupling agent via a prepolymer process. The molecular structure of copolyurethanes was confirmed by attenuated total reflectance-Fourier transform-infrared spectroscopy (ATR–FTIR), nuclear magnetic resonance spectrometry (NMR), and gel permeation chromatography (GPC). The impact sensitivity, mechanical performance, and thermal behavior of PBFMO-b-GAP were studied by drop weight test, X-ray photoelectron spectroscopic (XPS), tensile test, scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and thermal gravimetric analysis (TGA), respectively. The results demonstrated that the introduction of fluoropolymers could evidently reduce the sensitivity of GAP-based polyurethane and enhance its mechanical behavior (the tensile strength up to 5.75 MPa with a breaking elongation of 1660%). Besides, PBFMO-b-GAP exhibited excellent resistance to thermal decomposition up to 200 °C and good compatibility with Al and cyclotetramethylene tetranitramine (HMX). The thermal performance of the PBFMO-b-GAP/Al complex was investigated by a cook-off test, and the results indicated that the complex has specific reaction energy. Therefore, PBFMO-b-GAP may serve as a promising energetic binder for future propellant formulations.

Surface Modification of Magnetite with PBS Using a Ricinoleic‐Toluene Diisocyanate Fragment as the Binder Structure

AbstractMagnetite nanoparticles are widely used in current medicine because their magnetite properties allow several uses as drug delivery systems, contrasts in imaging tests, and even for magnetohyperthermia. However, magnetic nanoparticles possess meager Zeta potential, presenting a strong tendency to agglomerate. For clinical use, they must be covered with a biocompatible material to maintain colloidal stability, without, however, altering its magnetic properties. Thus, for biomedical applications in general, magnetic nanocomposites are more interesting than pure magnetite. The present work applies poly(butylene succinate) (PBS), as a coating on magnetite nanoparticles, aiming to increase their biocompatibility. PBS is a polymer obtained from renewable sources, being entirely suitable for pharmacological uses. In this work, the synthesis of ricinoleic acid from natural castor oil is carried out through the saponification method and subsequent acid hydrolysis. In turn, the synthesis of magnetite nanoparticles is performed by coprecipitation. Then, by an acid‐base reaction, the nanoparticles are treated with ricinoleic acid. Soon afterward, toluene diisocyanate is used to produce bonding between the modified particles and PBS. Fourier‐transform infrared spectroscopy confirms the synthesis of the material. Also, scanning electron microscopy and dynamic light scattering experiments are performed. The obtained results allow inferring the success in the preparation of the pursued hybrid material.

New reprocessable branched polyurethane from biorenewable sources

Thermally-remendable and recyclable polyurethane was obtained via Diels-Alder reaction using branched glycol Voranol 3138 (glycerin-derived block-copolymer of polyethylene and polypropylene) as soft segment and toluene-2,4-diisocyanate (TDI) as hard segment subsequently functionalized by terminal difurfurylamine groups. By cross-linking via Diels-Alder reaction with N,N’-bismaleimido-4,4′-diphenylmethane (BMI) new self-healing branched polyurethane was obtained. Polymer structure was characterized by NMR and IR spectroscopy along with thermal analysis methods (DSC and TGA). Resulting material has good processability and opportunity for recycling.

Preparation of Poly(ethylene glycol)@Polyurea Microcapsules Using Oil/Oil Emulsions and Their Application as Microreactors.

The development process of catalytic core/shell microreactors, possessing a poly(ethylene glycol) (PEG) core and a polyurea (PU) shell, by implementing an emulsion-templated non-aqueous encapsulation method, is presented. The microreactors’ fabrication process begins with an emulsification process utilizing an oil-in-oil (o/o) emulsion of PEG-in-heptane, stabilized by a polymeric surfactant. Next, a reaction between a poly(ethylene imine) (PEI) and a toluene-2,4-diisocyanate (TDI) takes place at the boundary of the emulsion droplets, resulting in the creation of a PU shell through an interfacial polymerization (IFP) process. The microreactors were loaded with palladium nanoparticles (NPs) and were utilized for the hydrogenation of alkenes and alkynes. Importantly, it was found that PEG has a positive effect on the catalytic performance of the developed microreactors. Interestingly, besides being an efficient green reaction medium, PEG plays two crucial roles: first, it reduces the palladium ions to palladium NPs; thus, it avoids the unnecessary use of additional reducing agents. Second, it stabilizes the palladium NPs and prevents their aggregation, allowing the formation of highly reactive palladium NPs. Strikingly, in one sense, the suggested system affords highly reactive semi-homogeneous catalysis, whereas in another sense, it enables the facile, rapid, and inexpensive recovery of the catalytic microreactor by simple centrifugation. The durable microreactors exhibit excellent activity and were recycled nine times without any loss in their reactivity.

Prevention of IL-6 signaling ameliorates toluene diisocyanate-induced steroid-resistant asthma

BackgroundAccumulating evidence indicated the crucial role for interleukin 6 (IL-6) signaling in the development of allergic asthma. Yet, the role of IL-6 signaling in toluene diisocyanate (TDI)-induced mixed granulocytic airway inflammation still remains unclear. Thus, the aims of this study were to dissect the role of IL-6 signaling and to evaluate the effect of tocilizumab on TDI-induced steroid-resistant asthma. MethodsTDI-induced asthma model was prepared and asthmatic mice were respectively given IL-6 monoclonal antibody, IL-6R monoclonal antibody (tocilizumab, 5 mg/kg, i.p. after each challenge) for therapeutic purposes or isotype IgG as control. ResultsTDI exposure just elevated IL-6R expression in the infiltrated inflammatory cells around the airway, but increased glycoprotein 130 expression in the whole lung, especially in bronchial epithelium. Moreover, TDI inhalation increased airway hyperresponsiveness (AHR) to methacholine, coupled with mixed granulocytic inflammation, exaggerated epithelial denudation, airway smooth muscle thickening, goblet cell metaplasia, extensive submucosal collagen deposition, dysregulated Th2/Th17 responses, as well as innate immune responses and raised serum IgE. And almost all these responses except for raised serum IgE were markedly ameliorated by the administration of IL-6 neutralizing antibody or tocilizumab, but exhibited poor response to systemic steroid treatment. Also, TDI challenge induced nucleocytoplasm translocation of HMGB1 and promoted its release in the BALF, as well as elevated lung level of STAT3 phosphorylation, which were inhibited by anti-IL-6 and anti-IL-6R treatment. ConclusionsOur data suggested that IL-6 monoclonal antibody and tocilizumab might effectively abrogate TDI-induced airway inflammation and remodeling, which could be used as a clinical potential therapy for patients with severe asthma.

Topical treatment with mastic (resin from Pistacia lentiscus) elicits anti-inflammatory and anti-pruritic responses by modulating keratinocyte activation in a mouse model of allergic dermatitis

BackgroundAs the number of patients with skin allergies, including atopic dermatitis, has increased rapidly, therapeutic options such as anti-IL-31 antibody and Janus kinase inhibitor have been developed recently. However, many concerns remain regarding the adverse effects and cost of these drugs; therefore, development of supplements that could support the effect of therapeutic agents is always required. PurposeThe aim of this study was to develop preventive and supportive options for skin allergies by focusing on a natural product called “Mastic”. Methods: Initially, the anti-inflammatory and anti-pruritic responses of 3% and 30% Mastic topical treatment were investigated in a mouse model of allergic contact dermatitis, generated by topical application of toluene-2,4-diisocyanate (TDI), a hapten that induces type 2 helper T cells. After itch behaviour and ear-swelling response were monitored, serum, auricular lymph nodes, and skin tissues were collected to analyse immunocyte differentiation, cytokine determination, and histological changes. ResultsOur findings indicated that topical treatment with mastic significantly ameliorated ear swelling, itch behaviour, immunocyte infiltration, and cytokine production. Histological evaluation confirmed the occurrence of anti-inflammatory responses. The anti-inflammatory and anti-pruritic effects of topical treatment with mastic (3% and 5%) were further confirmed in a mouse model of atopic dermatitis which was generated by topical application of TDI in NC/Nga mice. Thickness of the back skin, AD score, transepidermal water loss (TEWL), and itch behaviour were measured weekly, and immunocyte differentiation, cytokine determination, and histological changes were also analysed. Mastic treatment significantly attenuated the skin thickness, AD score, TEWL, and itch behaviour. Corroborated reduction was observed in the numbers of T cells and IgE-B cells, as well as in pro-inflammatory cytokine production. The reproducibility of the effects of mastic was confirmed with 1% mastic ointment in a setting similar to the AD mouse model. In vitro evaluation of keratinocytes indicated that mastic pre-exposure induced a significant dose-dependent decrease in cytokine production. ConclusionOur findings thus demonstrate that topical treatment with mastic significantly ameliorate inflammatory and pruritic responses in a mouse model of allergic dermatitis.

Assessment of site-specific greenhouse gas emissions of chemical producers: Case studies of propylene and toluene diisocyanate

The chemical industry accounts for 20% of global industrial greenhouse gas (GHG) emissions and the plastics production is increasing worldwide by approx. 4% annually. To reduce GHG emissions and increase GHG transparency in chemical value chains despite industrial secrets, we developed an approach to estimate the product carbon footprint of chemicals site-specifically without using classified production data. The new approach, is applied to two comparative case studies: propylene and toluene diisocyanate (TDI) production in Germany. The case study analyses 23 crackers on 17 production sites and four TDI production sites in Germany. The results indicate significant GHG emissions variations between productions sites (Cradle-to-Gate) that could not be quantified before. Among the production sites, product-specific GHG emissions range between 0.95 and 1.51 kgCO2e/kg propylene (reduction potential of GHG emissions of 37.1%) and between 3.17 and 3.62 kgCO2e/kg TDI (reduction potential of GHG emissions of 12.4%). This indicates massive differences in GHG efficiency in the production of propylene and TDI and an immense GHG emission reduction potential in the manufacture of plastic-intensive products (e.g. in the automotive sector) by increased transparency and informed supplier selection and procurement decision making. The method is transferable to chemical sites worldwide and indicates an even higher GHG reduction potential worldwide.

Fully recyclable and high performance phenolic resin based on dynamic urethane bonds and its application in self-repairable composites

A fully recyclable phenolic resin (TDNR) with dynamic cross-linked network was facilely prepared without any catalyst using commercial novolac and toluene diisocyanate by forming hindered urethane bonds. TDNRs not only preserved the intrinsic mechanical strength of classic phenolic resin, but also displayed efficient stress relaxation behaviour. The bulk TDNR exhibited a glass transition temperature up to 200 °C and tensile strength up to 55 MPa. Both the chemical and mechanical features of TDNR were effectively preserved after five recycle circulations. The recyclable TDNR can serve as a universal resin matrix either for molding compounds which are easily repairable or for fiber-reinforced composites with good processibility. The exchangeable network of TDNR ensures good processibility for long fiber prepregs, which are suitable for hand molding and reshape of composites. By utilizing a “simple” chemistry mechanism, the close-loop recycle of phenolic resin with high working temperature and good mechanical properties are successfully achieved.

Synthesis and Fabrication of Supramolecular Polydimethylsiloxane-Based Nanocomposite Elastomer for Versatile and Intelligent Sensing

High-performance strain sensors featuring self-healing ability and high stretchability are desired for human motion detection, soft robotics, and diver intelligent applications. Herein, a novel self-healing elastomer was synthesized via a facile one-pot polycondensation reaction between bis(3-aminopropyl) terminated polydimethylsiloxane and 2,4’-tolylene diisocyanate, followed by introducing carboxyl-functionalized multiwalled carbon nanotubes (CNTs). The physically entangled linear molecular chains and multiple hydrogen bonds endowed elastomer with a remarkable healing efficiency of 98.1% and outstanding stretchability of over 1000%. Owing to the conductive network constructed by the uniformly dispersed CNT, the nanocomposite elastomer-based strain sensor achieved a high gauge factor of 2.43 and its sensing performance could be well regained after self-healing. The strain sensor was successfully used for detecting various human motions and distinguishing facial microexpressions. Moreover, the nanocomposite elastomer applied on a grip ball and woolen glove as sensing units rendered them with the ability of grip force detection and sign language recognition. This work offers a new route and a promising self-healing nanocomposite elastomer for the development of recyclable and sustainable high-performance strain sensors and prospects its advanced intelligent applications.

Preparation of hetero-armed POSS-cored star-shaped PCL-PLA/PLA composites and effect of different diisocyanates as compatibilizer

Eight-armed A4B4-type hetero-arm star-shaped PCL-PLA polymers ((PCL)4-POSS-(PLA)4, SPLA30) with POSS core were successfully prepared via combination of the “arm-first” approach utilizing ring-opening polymerization (ROP) and click chemistry techniques. Firstly, alkyne-functional PLA and PCL polymers having arms with 30 repeating units were synthesized via ROP with utilizing propargyl alcohol as initiator and stannous octoate (Sn(Oct)2) as catalyst. Then, the obtained hetero-armed star-shaped polymers were prepared by Cu(I)-catalyzed alkyne-azide cycloaddition (CuAAC) click reaction between alkyne functional polymers (1:1 PCL:PLA) and azido functional polyhedral oligomeric silsesquoxane (POSS-(N3)8) molecules. Finally, these obtained star-shaped SPLA30 was blended with neat PLA at different PLA/SPLA30 ratios (95/5 and 90/10 wt%) via melt blending by utilizing micro-compounder (a lab-scale) to enhance thermal, morphological, and mechanical properties of neat PLA. Also, different diisocyanates (1,4-phenylene diisocyanate (PDI), isophorone diisocyanate (IPDI), methylene diphenyl diisocyanate (MDI), and toluene 2,4-diisocyanate (TDI)) at constant ratio (1 wt%) were used as a chain extender bonding terminal group of polymers. It was found that addition of SPLA30 and SPLA30+ diisocyanates provided improvements in mechanical properties (especially in elongation at break and impact strength) of neat PLA. When the thermal properties were examined, it was seen that the decomposition temperatures of the blends decreased significantly compared to neat PLA and that there was a significant increment in the Tg and Tm values. In addition, it has been found that especially the diisocyanates added to provide good interfacial adhesion with polymer blends and show a homogeneous distribution on the surface.

Effects of toluene-di-isocyanate microcapsules on the frost resistance and self-repairing capability of concrete under freeze-thaw cycles

Concrete buildings used in severe cold regions are susceptible to freeze-thaw damage, resulting in internal cracking and surface spalling of concrete. Microcapsules can self-repair concrete cracks and improve the durability of concrete. This paper focuses on the effects of toluene-di-isocyanate (TDI) microcapsules on the frost resistance and self-repairing capability of concrete under freeze-thaw cycles. The mass and mechanical properties of concrete were measured before and after freeze-thaw cycles. The pore size distribution and microstructure of the concrete were characterized using nuclear magnetic resonance and scanning electron microscopy (SEM). The mechanical properties and permeability of freeze-thaw damaged concrete were assessed by compressive strength tests and rapid chloride migration (RCM) tests after self-repairing. The frost resistance and self-repairing capability of concrete containing microcapsules were also evaluated by ultrasonic test. The results showed that the concrete containing nano-SiO2/paraffin/PE wax encapsulated TDI microcapsules (CON3) had better frost resistance and self-repairing capability than the concrete containing other microcapsules. After 100 freeze-thaw cycles, the mass loss rate and compressive strength loss rate of CON3 were only 1.63% and 13.6%, respectively. After 7 d of self-repairing, SEM images showed that repairing products with network structure appeared in the pores of CON3, which improved the microstructure of concrete. The harmful pores proportion, compressive strength recovery rate, chloride diffusion coefficient recovery rate, maximum amplitude and dominant frequency maximum amplitude of CON3 were 47.8%, 96.9%, 84.6%, 77.99 mV and 8.37 mV, respectively.

SILICON-CONTAINING OLIGOMERIC AZOINITIATORS IN THE SYNTHESIS OF BLOCK COPOLYMERS

The aim of the work was to develop methods for the synthesis and study of the properties of silicon-containing oligomeric azo- and polyazoinitiators based on bis-γ-hydroxypropylpolysiloxane (HPS) and bis-γ-aminopropylpolysiloxane (APS). Silicon-containing oligomeric azoinitiators using HPS were synthesized on the basis of cyclohexanone azo-bis-isobutyrohydrazone (AGN-CH) and bis-γ-hydroxypropylpolysiloxane bifunctional macrodiisocyanate (MDIHPS). MDIHPS was obtained by the interaction of GPS with 2,4 toluene diisocyanate (2,4-TDI). Oligomeric azoinitiators have been obtained, which have the structure RXR and (RX)nR, where R is a propylpolysiloxane block, X is a azo initiator block. For the synthesis of an oligomeric azo initiator based on bis-γ-aminopropyl polysiloxane (APS), a method was first developed for the synthesis of a monomeric azo initiator with terminal oxadiazolinylcarbamanate isocyanate groups (AGN-NCO) by the interaction of AGN-CH and 2,4-TDI at a molar ratio of 1: 2. On the basis of the obtained AGN-NCO and APS at a molar ratio of AGN-NCO: APS = 1: 1, an oligomeric azo initiator (OAI APS-P) was synthesized, which has the structure (RX)nR, where R is a propylpolysiloxane block, X is an azo initiator block. The structures of monomeric and oligomeric azo initiators have been studied by UV and IR spectroscopy, and the kinetic regularities of their synthesis have been calculated. On the basis of oligomeric azo initiators and styrene, block copolymers of the (AB)nA type were obtained by the method of thermal and photoinitiated radical polymerization, where A is a propylpolysiloxane block, B is an oligosyrene block with a constant value of the organosilicon block and a different size of the oligostyrene block. The structure of block copolymers was investigated by IR spectroscopy. It was shown that during photopolymerization, oligostyrene blocks of shorter length are formed than during thermopolymerization, and possible oxidation processes. The study of relaxation transitions by DSC in oligostyrene and propylpolysiloxane blocks of the BCP showed that the common heat capacity curves are the presence of two jumps in the heat capacity at the glass transition temperatures of the polysiloxane and oligostyrene microphase. A slight shift in the glass transition temperature of polysiloxane microphases in BCP towards higher temperatures compared to the homopolymer may be associated with the effect of oligostyrene microphase. With a decrease in the length of the oligosyrene block, a low-temperature shift in the glass transition temperature of oligostyrene blocks relative to the homopolymer and a depression of ∆Cp,2 are observed, which is associated with the suppression of mobility in oligodienic microphases by less mobile propylpolysiloxane blocks.