Tetrafunctional Monomer Research Articles

Reversible Photo-Responsive Hydrophobic Coating Synthesized from Lignin-Derivable Molecules on Nanocellulose Films for Packaging Applications.

Paper-based packaging can offer a sustainable replacement for plastics. However, paper provides a poor barrier to water, oxygen and moisture. This study presents a novel renewable lignocellulosic composite made from a hydrophobic photo-reversible coating deposited onto a cellulose nanofiber film that has improved barrier properties and can be reprocessed. Diglycerol and lignin-derivable aldehyde were reacted to form a tetra-functional monomer with photo-responsive unsaturated double bonds that can be converted to covalent cyclobutane rings to create reversibly crosslinkable network upon UV-irradiation. The photo-responsive compound was applied as a thin coating of thickness 2.7±0.4 μm over cellulose nanofiber (CNF) films of thickness 80±19 μm. The surface of the coated films became hydrophobic with a contact angle (CA) of 93.1±1.7° and displayed a low water vapour transmission rate (WVTR) of 16±2 g/m2/day vs. 30.7±1.5° CA and 81±11 g/m2/day WVTR for uncoated CNF films. The coated film is also oleophobic, an attractive feature for food packaging applications. The reversible photo-reaction enables the crosslinked covalent network to be broken down to unsaturated double bonds once exposed to a higher-energy UV irradiation, allowing reprocessing and recycling. The novel coating was developed using a sustainable green synthesis method (process simple E factor 0.9).

Influence of the polymer network on the stability of the heliconical structure in the ferro- and antiferroelectric liquid crystalline phases

The use of polymer networks to stabilise chiral liquid crystalline materials (ChLC), which canfind applications in electro-optical and photonic devices, is becoming increasingly common. Stabilisingthe heliconical structure of a ChLC using a polymer network involves forming a spatial polymer matrix ina liquid crystal medium. The polymer network acts as a kind of scaffold for the liquid crystal molecules,resulting in the helix being stiffened in a particular desired state. This method of helix stabilisation hasbeen mainly used in chiral nematic liquid crystals so far. Effective stabilising the helix with a polymerin chiral smectic liquid crystals could eliminate the main drawback of these materials, i.e., the changein their performance, in electro-optical effects based on the deformation of the helix, with a changein temperature. The main parameter characterising the heliconical structure is its pitch, whose valuechanges rapidly with temperature change, in most smectic liquid crystals, which in turn translates intothe above-mentioned drawbacks. Stabilisation with the polymer should translate into temperaturestability of the helical pitch and the rest of the material parameters. This paper presents the results ofthe temperature dependence of the helical pitch before and after polymerisation of a liquid crystalmaterial with an antiferroelectric phase. A tetrafunctional monomer structurally compatible to thecomponents of the antiferroelectric mixture and, for comparison, a commercially available monomerwith a different structure were used in the study. The results relevant that stabilisation of the heliconicalstructure is easier after the use of a monomer more structurally compatible to the components ofparent liquid crystal material, while maintaining homogeneity of the heliconical structure orderingand a wide temperature range of the antiferroelectric phase occurrence.Keywords: liquid crystals, antiferroelectric phase, helical pitch, polymerization

Examining the Quasi-Static Uniaxial Compressive Behaviour of Commercial High-Performance Epoxy Matrices.

Four commercial high-performance aerospace aromatic epoxy matrices, CYCOM®890, CYCOM®977-2, PR520, and PRISM EP2400, were cured to a standardised 2 h, 180 °C cure cycle and evaluated in quasi-static uniaxial compression, as well as by dynamic scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The thermoplastic toughened CYCOM®977-2 formulation displayed an overall increase in true axial stress values across the entire stress-strain curve relative to the baseline CYCOM®890 sample. The particle-toughened PR520 sample exhibited an overall decrease in true axial stress values past the yield point of the material. The PRISM EP2400 resin, with combined toughening agents, led to true axial stress values across the entire plastic region of the stress-strain curve, which were in line with the stress values observed with the CYCOM®890 material. Interestingly, for all formulations, the dilation angles (associated with the volume change during plastic deformation), recorded at 0.3 plastic strain, were close to 0°, with the variations reflecting the polymer structure. Compression data collected for this series of commercial epoxy resins are in broad agreement with a selection of model epoxy resins based on di- and tetra-functional monomers, cured with polyamines or dicarboxylic anhydrides. However, the fully formulated resins demonstrate a significantly higher compressive modulus than the model resins, albeit at the expense of yield stress.

Contribution of Dynamic Rheology Coupled to FTIR and Raman Spectroscopies to the Real-Time Shaping Ability of a Hyperbranched Polycarbosilane.

In the field of non-oxide ceramics, the polymer-derived ceramic (PDC) approach appears to be very promising, especially for obtaining easily shaped and homogeneous materials in terms of structure and composition. However, in order to reach a suitable form during the process, it is often necessary to study the rheology of preceramic polymers while they are modified during polymerisation or crosslinking reactions. Given this need in the understanding of the real-time rheology of macromolecules during their synthesis, a rheometer coupled with both an infrared spectrometer and a Raman probe is described as a powerful tool for monitoring in situ synthesised polycarbosilanes. Indeed, this original device allows one to control the viscosity of a hyberbranched polycarbosilane from defined difunctional and tetrafunctional monomers. Meanwhile, it links this evolution to structural modifications in the macromolecular structure (molar masses, dispersity and conformation), based on SEC-MALS analyses, synchronised by the monomer conversion determined by using Raman and infrared spectroscopies, a common denominator of the aforementioned instrumental platform.

The comparison of self-assembling behaviour of phenyl biphenylcarboxylate and biphenyl benzoate compounds with the different length and shape of chiral terminal chain

Our recent advances on polymer-stabilised orthoconic antiferroelectric liquid crystals (PSOAFLCs) eliminated the asymmetry of switching times in electro-optical effect based on surface stabilized OAFLCs and paved the way for their effective use in many photonic and optoelectronic devices requiring very fast switching. To fabricate new modifications of PSOAFLCs, besides bi- and tetrafunctional monomers, multicomponent AFLCs mixtures with a very low meting point, high stability of the antiferroelectric phase at lower temperatures and higher helical pitch length are desirable. Herein, a very convenient synthetic method of new AFLC compounds with a phenyl biphenylcarboxylate structure of the rigid core with different length and shape of terminal chains is reported. The resulting mesomorphic properties and helical parameters are compared with those of analogues with a biphenyl benzoate structure of the rigid core. The designed AFLC compounds clearly possess definite advantages. Specifically, they exhibit lower meting points, higher clearing points, broader temperature range of the antiferroelectric phase (SmCA*) and much longer helical pitch length, especially for analogues with the shortest achiral terminal chain, but unexpectedly lower tendency to give the direct transition between the antiferroelectric and isotropic phase. The introduction of the cycloalkyl ring at the end of the chiral terminal chain increases the melting points, flattens the temperature dependence of the helical pitch and changes the sense of the helical twist, but also enhances the ability of the direct SmCA*-Iso phase transition, regardless the type of the rigid core. The obtained results highlight a possibility of utilizing compounds with the phenyl biphenylcarboxylate structure of the rigid core, designed under this work, together with previously prepared compounds with the biphenyl benzoate rigid core to formulate multicomponent OALFC mixtures with a very low melting point and a very high helical pitch length.

The Influence of Silica Nanoparticles on the Thermal and Mechanical Properties of Crosslinked Hybrid Composites.

This paper presents the synthesis and physicochemical characterization of a new hybrid composite. Its main goals are evaluating the structure and studying the thermal and mechanical properties of the crosslinked polymeric materials based on varying chemical properties of the compounds. As an organic crosslinking monomer, bisphenol A glycerolate diacrylate (BPA.GDA) was used. Trimethoxyvinylsilane (TMVS) and N-vinyl-2-pyrrolidone (NVP) were used as comonomers and active diluents. The inorganic fraction was the silica in the form of nanoparticles (NANOSiO2). The hybrid composites were obtained by the bulk polymerization method using the UV initiator Irqacure 651 with a constant weight ratio of the tetrafunctional monomer BPA.GDA to TMVS or NVP (7:3 wt.%) and different wt.% of silica nanoparticles (0, 1, 3%). The proper course of polymerization was confirmed by the ATR/FTIR spectroscopy and SEM EDAX analysis. In the composites spectra the signals correspond to the C=O groups from NVP at 1672–1675 cm−1, and the vibrations of Si–O–C and Si–O–Si groups at 1053–1100 cm−1 from TMVS and NANOSiO2 are visible. Thermal stabilities of the obtained composites were studied by a differential scanning calorimetry DSC. Compared to NVP the samples with TMVS degraded in one stage (422.6–425.3 °C). The NVP-derived materials decomposed in three stages (three endothermic effects on the DSC curves). The addition of NANOSiO2 increases the temperature of composites maximum degradation insignificantly. Additionally, the Shore D hardness test was carried out with original metrological measurements of changes in diameter after indentation in relation to the type of material. The accuracy analysis of the obtained test results was based on a comparative analysis of graphical curves obtained from experimental tests. The values of the changes course of similarity in the examined factors, represented by those of characteristic coefficients were determined based on the Fréchet’s theory.

Evaluation of Sealing Properties to LED Light Emitting Substrate of Organic-inorganic Hybrid Materials Composed of Polysilsesquioxane with Thiol Group

Novel organic-inorganic hybrid materials were developed as LED sealants. Polysilsesquioxane with an -SH group (PSQ-SH) and acrylic monomer were selected as the inorganic and organic components, respectively. Trimethylolpropane trimethacrylate (TRIM), which is a trifunctional monomer, was selected as an acrylic monomer, and curing of the material was performed by the thiol-ene reaction. The LED was sealed using the prepared PSQ-SH/TRIM hybrid material (PTH), and a light emission test was performed. However, cracks occurred in the hybrid material during lighting. Therefore, ditrimethylol propane tetraacrylate (DTMPTA), which is a tetrafunctional monomer, was selected for the first time to prepare a PSQ-SH/DTMPA hybrid material (PDH) in order to enhance the strength and heat resistance of the material. The characteristics of the novel PDH were evaluated and compared with those of PTH. Specifically, the heat resistance was evaluated by confirming the onset temperature of weight reduction using thermogravimetry-differential thermal analyzer (TG-DTA) analysis, and the mechanical strength was also evaluated by bonding the glass substrates with a hybrid material and measuring the sealing strength. In conclusion, it was possible to suppress crack generation during lighting by using PDH instead of PTH in the light emission test.

Polymer stabilized highly tilted antiferroelectric liquid crystals - the influence of monomer structure and phase sequence of base mixtures

Polymer stabilization offers unique opportunities for improving features of liquid crystals. In particular, it influences the static and dynamic performance of antiferroelectric liquid crystals (AFLCs) due to the stabilization of surface-stabilized geometry of such self-assembling materials forming anticlinic structures. The main advantages of polymer-stabilized AFLCs consist of a significant decrease of the electro-optical switching time, and a lower sensitivity to mechanical shock and temperature changes in working devices. This work experimentally analyzes the effect of functionality of selected mesogenic monomers on the properties of new developed high-tilted AFLC mixtures with different phase sequences, before and after polymer stabilization. It was found that tetrafunctional monomers (especially those with non-chiral terminal chains) reduce the thermal stability of antiferroelectric phase and increase helical pitch at low temperatures before polymerization. However, they reduce values of the tilt angle and spontaneous polarization and simultaneously flatten the temperature dependence after polymerization to a greater extent than bifunctional monomers. Tetrafunctional monomers improve electro-optical characteristics of tested AFLC mixtures after polymer stabilization. On the other hand, polymer-stabilized materials based on bifunctional monomers and LC mixtures with direct SmCA* - Iso phase transition show acceptable electro-optical performance in device cells. Most importantly, the obtained results confirm definite advantages of using mixtures with direct SmCA* - Iso phase transition when designing new polymer-stabilized AFLC materials with appropriate features in effects based on surface-stabilized geometry.

Intrinsically Microporous Polymer Nanosheets for High-Performance Gas Separation Membranes.

Microporous polymer nanosheets with thicknesses in the range 3-5 nm and with high apparent surface area (Brunauer-Emmett-Teller surface area 940 m2 g-1 ) are formed when the effectively bifunctional (tetrafluoro) monomer used in the preparation of the prototypical polymer of intrinsic microporosity PIM-1 is replaced with an effectively tetrafunctional (octafluoro) monomer to give a tightly crosslinked network structure. When employed as a filler in mixed-matrix membranes based on PIM-1, a low loading of 0.5 wt% network-PIM-1 nanosheets gives rise to enhanced CO2 permeability and CO2 /CH4 selectivity, compared to pure PIM-1.

Shape memory polymer networks based on methacrylated fatty acids

In this study, bio-based materials were prepared from fatty acid precursors and variable amounts of styrene or divinylbenzene by free-radical polymerization. The obtained materials were highly translucent and resulted insoluble in common organic and aqueous solvents. They exhibit a complex microstructure due to the formation of highly cross-linked arrangements (micro/nanogels) closed packed into clusters. The bio-polymers prepared with divinylbenzene (a tetra-functional monomer), due to their excessive cross-linkage, resulted in brittle samples whose mechanical response could not be obtained. On the other hand, bio-based polymers obtained from styrene (a bi-functional monomer) resulted in materials with a moderate cross-linking density, a sharp glass-rubber transition and acceptable mechanical properties, leading to polymers with interesting shape memory response (switching temperature, fixity and recovery ratios) that could be tailored by changing the composition. In these materials it was corroborated that higher (but not excessive) cross-linking density led to a greater shape recovery, since cross-links are the responsible for memorizing the original shape of the material.

Photoreversible Smart Polymers Based on 2π + 2π Cycloaddition Reactions: Nanofilms to Self-Healing Films

A simple nanostructured, photoresponsive film made from a coumarin-modified tetrafunctional monomer, which is both photodegradable and photoreproducible, was prepared using a simple spin-coating pr...

A reduced graphene oxide ceramic electrode modified with one MoNomer doubly imprinted acryloylated tetraamine cobalt phthalocyanine polymer for the simultaneous analysis of anticancerous drugs

The present work illustrates a novel technique for the development of One MoNomer dual imprinted polymer, utilizing acryloylated tetraamine cobalt phthalocyanine as a tetrafunctional monomer, on the surface of a reduced graphene oxide ceramic electrode. This electrode was used for the simultaneous analysis of a mixture of anticancerous drugs, chlorambucil and dacarbazine, at ultra-trace level in real samples. The acryloylated tetraamine cobalt phthalocyanine was typically selected in this work for polymerization because it served both as a monomer and a crosslinker, with higher electroconductivity. The detection sensitivity of the measurement was realized to be 0.041 ng mL−1 and 0.017 ng mL−1 for chlorambucil and dacarbazine, respectively in the aqueous environment. The complex matrices of blood plasma, urine and pharmaceutics were examined which yielded the validated results without any effects of matrix complications including cross-reactivity, and false-positives. The therapeutic ranges of the test analyte(s) (chlorambucil 0.159–28.524 ng mL−1, dacarbazine 0.063–37.286 ng mL−1) were realized to be larger demonstrating perfect linearity (R2 = 0.99) with the improved voltammetric response. This work merits special significance to decide the adequate supplementation of drug(s) in combined therapy for cancer treatment.

Synthesis of a high-performance citric acid-based polyester elastomer by a hot-pressing technique

The high-performance bio-based elastomer, poly (1, 4-cyclohexanedimethanol succinate-co-citrate) (PCSC), was successfully synthesized through the combination of melt polymerization and hot pressing. Owing to the structural characteristics of citric acid (CA), an effective process of thermal- and pressure-integrated crosslinking was possible, revealing CA to be a progressive tetra-functional monomer. In the composition of PCSC, there can be four types of ester bonds amongst monomers, of which CA was used in three. Specifically, the stepwise hot-pressing method allowed β-carboxylic acid and hydroxyl group of CA to remain within the synthesized elastomer to enhance its crosslinking density via esterification. As a result, the synthesized PCSC possessed a wide range of mechanical properties along with good thermal resistance. The resulting characteristics were demonstrated by fourier-transform infrared spectroscopy (FT-IR), two-dimensional correlation spectroscopy (2D-COS), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and tensile and swelling tests. PCSC is a sustainable and versatile material that can be utilized in the field of engineering.

Catalyst- and solvent-free, thermal generation of microporous polymer networks

Multifunctional iodoaryl monomers were used for the catalyst- and solvent-free generation of microporous polymer networks of high surface areas up to 732 m2 g−1. The thermal conversion of the monomers relies on the homolytic cleavage of weak iodine–carbon bonds followed by a C–C coupling of the radicalic intermediates. By using tri- or tetrafunctional monomers and by tuning reaction temperature and time, the optimum reaction conditions allow the formation of the corresponding microporous networks in good yields of 71%–86%. The resulting networks exhibit notable high CO2 and H2 adsorption capacities of up to 8.89 wt% (273 K, 1 bar) and up to 1.31 wt% (77 K, 1 bar), respectively.

Thermal degradation behavior of lignin-modified porous styrene-divinylbenzene and styrene-bisphenol A glycerolate diacrylate copolymer microspheres

This paper describes the thermal properties of polymeric porous microspheres that contain a natural wood-derived polymer, lignin, as one of the components. Polymeric microspheres were obtained by the reaction of divinylbenzene (DVB) or bisphenol A glycerolate diacrylate (BPA.DA) with styrene (St) and a lignin component. The lignin components were unmodified lignin (L), lignin esterified with acrylic acid (LA) or lignin initially reacted with epichlorohydrin and then with acrylic acid (LEA). The copolymers were obtained by emulsion-suspension polymerization at a constant mole ratio of the tetrafunctional monomer DVB or BPA.DA to styrene St (1:1w/w) and different types of lignin components. The thermal stabilities and degradation behavior of the obtained microspheres were studied by a thermogravimetric (TG/DTG/DSC) analysis. The evolved gases were analyzed by FTIR spectrometry. The influence of the lignin component on thermal properties of the obtained polymeric microspheres is evaluated and discussed. Due to the presence of the specific functional groups and well-developed porous structure, the obtained lignin-containing microspheres have a potential application as specific sorbents. Based on the high char content during the pyrolysis, the copolymers containing the lignin additives can be also considered as potential precursors for preparation of carbon materials.

Synthesis, characterization, and application of a new methylenethiol resins for heavy metal ions removal

ABSTRACTPolymeric matrices in the form of microspheres were obtained by copolymerization of the tetrafunctional monomers: 2,3-(2-hydroxy-3-methacryloyloxypropoxy)naphthalene (2,3-NAF.DM) or (bis[4(2-hydroxy-3-methacryloyloxypropoxy)phenyl]sulphide (BES.DM) with styrene (St). Next multistage modification which introduced the methylenethiol groups on the surface of copolymers was carried out. New materials were used in sorption processes to remove toxic heavy metal ions particularly Cd(II), Pb(II), Cu(II), Zn(II), and Ni(II) from aqueous solutions. The effects of the contact time on the sorption of the above-mentioned ions are presented. Sorption capacity depending on the type of monomers, modification, surface character, and porous structure of polymer was determined. The synthesized microspheres 2,3-NAF.DM-St-CH2SH and BES.DM-St-CH2SH indicate potential to adsorb heavy metal ions in the state and batch equilibrium systems.

Influence of the size of the cubic lattice and the activity of its walls on the kinetics of the formation of a unitary three-dimensional structural element

The results of Monte Carlo simulations of the kinetics of the three-dimensional free-radical polymerization of tetrafunctional monomers (TFM) in terms of the formation of a unitary three-dimensional structural element (UTSE) are presented. The process is simulation on 103 → 503-sized cubic lattices with walls of different activity with respect to free radicals. Changes in the degree of UTSE polymerization, number of crosslinks and cycles, mechanisms of chains crosslinking and cyclization and other parameters caused by changes of the conditions of three-dimensional free-radical polymerization of TFM, as well as the difference between the effects of active and inert walls, are reported.

Study of Porous Structures and Thermal Properties of Luminescent Polymeric Microspheres Derivatives of Naphthalene-2,7-Diol

We studied the porous structures and thermal properties of spherical shaped cross-linked polymers. These novel polymeric microspheres were synthesized by emulsion–suspension polymerization of aromatic tetrafunctional monomer [2,7-(2-hydroxy-3-methacryloyloxypropoxy)naphthalene (2,7-NAF.DM)] with typical, commercially available monomers (styrene, divinylbenze ne and methyl methacrylate). The monomer 2,7-NAF.DM was obtained in the twostep process. In the first step, the epoxy resin was synthesized by treating epichlorohydrin with naphthalene-2,7-diol. In the second step, the obtained epoxy derivatives were subjected to esterification with methacrylic acid. Porous structures of the obtained microspheres in the dry state were studied by nitrogen adsorption–desorption measurements. Thermal stabilities and degradation behaviours of the obtained co-polymers were characterized by differential scanning calorimetry and thermogravimetric/derivative thermogravimetry analyses. In addition, we also present the photolum...

A novel high performance oxazine derivative: design of tetrafunctional monomer, step-wise ring-opening polymerization, improved thermal property and broadened processing window

A novel tetrafunctional oxazine monomer containing benzoxazine and fluorene-oxazine was prepared for the first time using a Mannich condensation reaction of 2,7-dihydroxy-9,9-bis-(4-hydroxyphenyl)fluorene with paraformaldehyde and n-butylamine.

New Ion Exchangers Based on Copolymers: 2,3-(2-Hydroxy-3-Methacryloyloxypropoxy)Naphthalene–Styrene

Synthesis and characterization of the new polymeric ion exchangers with thiol and sulfonyl hydroxide groups are presented. These new sorbents were also compared with polymeric microspheres possessing methylenethiol groups on the surface presented previously. The polymeric cation ion exchangers in the form of microspheres were obtained by the suspension-emulsion polymerization tetrafunctional monomer: 2,3-(2-hydroxy-3-methacryloyloxypropoxy)naphthalene (2,3-NAF.DM) with styrene (St). Next, multistage modification introducing sulfur-containing group (thiol or sulfonyl hydroxide or methylenethiol) on the surface of polymeric matrices was made. In order to obtain sulfonyl hydroxide derivatives the matrices were performed as follows: the parent microspheres were treated by H2SO4 (Method I) or with the addition of oleum (Method II). The thiol groups were introduced in a two-stage reaction. In the first stage chlorosulfonation of parent microspheres in the presence of chlorosulfonic acid was carried out. Finally, the reduction of modified microspheres by using SnCl2·2H2O was conducted. The sulfur group content (elemental analysis, scanning electron microscope EDX SEM), thermal properties (thermogravimetric analysis), porous structure as well as the swelling characteristics of the functional beads were examined. The surface texture was also visualized by the AFM method.