Bifunctional Monomer Research Articles

Radical Cyclopolymerization of Isocyanurate Core-Based Bifunctional Monomers Bearing a Hydroxy Group and Their Application to Cross-Linking Reaction

We report the synthesis of linear polymers having macrocyclic units in the main chain and hydroxy groups in the side chains by radical cyclopolymerization of the isocyanurate core-based bifunctional monomers and their utilization to cross-linking reaction via esterification. The 5% weight loss temperature (Td5) and glass transition temperature (Tg) of the resulting linear polymers have clearly revealed the effect of the introduced macrocyclic unit upon the thermal stability of the polymer. Among the synthesized cross-linked polymers, the rigidity of the incorporated cross-linked structure in the cross-linked polymers also dominates thermal properties of polymers. Such reactive linear polymers including macrocyclic units and hydroxy groups are expected to be applied to various fields of high thermal-resistance materials.

Heat-Resistant Phthalonitrile-Based Resins for 3D Printing via Vat Photopolymerization

In this study, a maleimide/phthalonitrile bifunctional monomer PNB-M was used in vat photopolymerization via the maleimide group to obtain phthalonitrile-containing polymers suitable for further thermal postcuring. A high concentration (40 wt %) and low viscosity (less than 500 mPa·s at 25 °C) photopolymer resin was prepared from the phthalonitrile monomer PNB-M with 4-acryloylmorpholine as comonomer and trimethylolpropane trimethacrylate as cross-linker. Photo-DSC, NMR, and FTIR tests revealed free-radical photoinduced copolymerization of the maleimide with the acrylic groups during 3D printing. Postprinting thermal curing of the phthalonitrile groups was performed with different curing agents as well as via self-initiation by PNB-M. The developed phthalonitrile-containing polymerizable compositions made it possible to increase glass transition temperatures of the 3D printed polymer materials up to 351 °C after additional thermal postcuring. Moreover, mechanical properties of the 3D printed materials have been improved after curing of the phthalonitrile monomer in the maleimide–acrylate copolymer.

Spatially controlling the mechanical properties of 3D printed objects by dual-wavelength vat photopolymerization

To date, the 3D printing of polymers with heterogeneous and locally controlled material properties is still a challenging area in additive manufacturing. In terms of vat photopolymerization 3D printing, the fabrication of multi-material objects typically relies on an automatic material exchange of different resin vats. However, along with the high complexity of the printing equipment, this technique suffers from a low build speed and often yields 3D printed objects with week interlayer adhesion across the various material interfaces. Herein, we use chemo-selective wavelengths to fabricate objects with multi-material properties by dual-wavelength vat photopolymerization 3D printing employing a single vat. The photopolymers’ stiffness and flexibility are conveniently controlled by two photoreactions working at two different wavelengths. In particular, a dual photocurable resin is applied containing multi-functional acrylates, which are cured by a radical induced chain growth reaction at 405 nm, and bi-functional epoxy monomers, which additionally undergo cationic curing upon UV exposure (365 nm). FT-IR experiments confirm the wavelength selective network formation whilst dynamic mechanical analysis and tensile tests give evidence of the distinctive difference of the related mechanical properties. By being able to produce soft (ε = 24%, σ = 1.0 MPa) and stiff (ε = 4%, σ = 39.1 MPa) networks with a single resin vat, we demonstrate the efficient fabrication of 3D structures with locally controlled mechanical properties using a dual-wavelength 3D printer operating at 405 and 365 nm. In contrast to previous work in this field, we were able to significantly expand the range of mechanical properties by appropriate selection of the acrylic components and to drastically accelerate the build speed by changing the cationic photoinitiator and using a customized printer with high intensity LED sources.

Photo-induced ring-opening polymerization of trimethylene carbonate-based liquid resins: Towards biodegradable patterned coatings

Patterned coatings based on biodegradable crosslinked poly(ester/carbonate) have been prepared by photo-induced ring-opening polymerization of a liquid bifunctional trimethylene carbonate-based monomer using poly(ε-caprolactone) triol as initiator and a guanidine superbase photogenerator activated by irradiation at 385 nm. The influence of various parameters on gel time such as components molar ratios, irradiation time or reaction temperature, has been evaluated by photorheometry. The formulation and experimental conditions offering the shortest gel times were then employed to produce a patterned coating by stereolithography. Sample thickness proves to be independent of irradiation time, but increases with reaction time, thus attesting of a dark polymerization.

Specific Bifunctionalization on the Surface of Phosphorus Dendrimers Syntheses and Properties

Dendrimers are highly branched macromolecules possessing, in most cases, identical terminal functions. However, it is sometimes desirable to have two types of surface functions in order to fulfil specific properties. The stochastic functionalization is frequently used for such purposes, but the presence of an uncontrolled number of each type of terminal function, albeit acceptable for research purposes, has no practical use. Thus, it is highly desirable to find strategies suitable for the precise grafting of two different functional groups on the surface of dendrimers. The easiest way, and the most widely used, consists in using a bifunctional monomer to be grafted to all of the surface functions of the dendrimers. Two other strategies are known but are rarely used: the modification of an existing function, to generate two functions, and the sequential grafting of one function then of a second function. The three methods are illustrated in this review with polyphosphorhydrazone (PPH) dendrimers, together with their properties as catalysts, for materials, and as biological tools.

An advanced molecularly imprinted electrochemical sensor based bifunctional monomers for highly sensitive detection of nitrofurazone

The combination of molecularly imprinted technology and electrochemical sensor can prepare stable and excellent anti-interference molecularly imprinted electrochemical sensor (MIECS), realizing the highly specific recognition of nitrofurazone (NFZ). Bifunctional monomers and zeolitic imidazolate frameworks (ZIF) modified carboxylic multi-walled carbon nanotubes (c-MWCNTs) nanocompostites were used to solve the problems of low conductivity and limited number of imprinted holes in molecularly imprinted polymer (MIP) membrane. The porous nanocomposite can efficiently improve the conductivity and increase the surface of electrode, providing abundant molecularly imprinted holes and enabling a wide detection range. Nicotinamide (NA) and 2-amino-5-mercapto-1,3,4-thiadiazole (AMT) acted as bifunctional monomers and NFZ as template molecules, which were electropolymerized to MIP on the modified electrode. In the optimal experimental environment, the electrochemical response of MIECS to NFZ was linear in a certain concentration range. The linear range was from 10–13 M to 10–6 M, and the detection limit was 6.7 ×10–14 M. The MIECS showed excellent anti-interference performance, which was attributed to the unique holes generated by the polymerization of bifunctional monomers. MIECS also owned good stability and reproducibility and has been successfully applied to the detection of actual urine and water samples.

Synthetic Route to Conjugated Donor-Acceptor Polymer Brushes via Alternating Copolymerization of Bifunctional Monomers.

Alternating donor–acceptor conjugated polymers, widely investigated due to their applications in organic photovoltaics, are obtained mainly by cross-coupling reactions. Such a synthetic route exhibits limited efficiency and requires using, for example, toxic palladium catalysts. Furthermore, the coating process demands solubility of the macromolecules, provided by the introduction of alkyl side chains, which have an impact on the properties of the final material. Here, we present the synthetic route to ladder-like donor–acceptor polymer brushes using alternating copolymerization of modified styrene and maleic anhydride monomers, ensuring proper arrangement of the pendant donor and acceptor groups along the polymer chains grafted from a surface. As a proof of concept, macromolecules with pendant thiophene and benzothiadiazole groups were grafted by means of RAFT and metal-free ATRP polymerizations. Densely packed brushes with a thickness up to 200 nm were obtained in a single polymerization process, without the necessity of using metal-based catalysts or bulky substituents of the monomers. Oxidative polymerization using FeCl3 was then applied to form the conjugated chains in a double-stranded (ladder-like) architecture.

Poly(oligoethylene glycol methacrylate) Star‐Shaped Copolymers with Hydroxypropyl Methacrylate Cores

AbstractStar‐shaped copolymers with crosslinked hyperbranched cores, varying in both number and length of the arms, are prepared by the reversible addition‐fragmentation chain transfer (RAFT) polymerization technique. Star synthesis is conducted via a simple, “core‐first” method. Hydroxypropyl methacrylate monomer is used for the formation of the hyperbranched/crosslinked core, with ethylene glycol dimethacrylate used as a bifunctional monomer in the role of the cross‐linker. Two different cross‐linker/chain transfer agent ratios are chosen to manipulate the number of the arms in the final star nanostructure. Oligoethylene glycol methacrylate (OEGMA500) is used as a biocompatible and hydrophilic component for the creation and extension of the arms. Arm length is controlled by the amount of OEGMA monomer used in the second polymerization step. Molecular characterization of the four synthesized stars is achieved via size exclusion chromatography and nuclear magnetic resonance, which provides information regarding the molar mass, dispersity, and composition of each star‐shaped copolymer. Dynamic light scattering (DLS) studies of copolymers in N,N‐dimethyl formamide solutions provide sizes of individual copolymer molecules in the size range of 8–20 nm. Aqueous dispersions of copolymers are investigated by DLS, cryogenic transmission electron microscopy, and atomic force microscopy, which show the formation of spherical aggregates with diameters of 60–350 nm, dependent on the arm number and length of star copolymers. The obtained sizes and size distributions, along with the hydroxyl‐group‐bearing cores, indicate that the star copolymer can be used as potential nanocarriers for drugs or bioimaging agents.

Developing thermally resistant and strong biobased resin from benzoxazine synthesized using green solvents

Developing thermally resistant and strong biobased resin from benzoxazine synthesized using green solvents is still an important and challenging issue. Herein, starting from biomasses, a new bifunctional benzoxazine monomer (ST-fa) was synthesized using green solvents (ethanol, ethyl acetate) during the whole synthesis and purification processes. The curing behavior and kinetics of ST-fa were studied with differential scanning calorimetry. Results show that ST-fa has outstanding process-ability reflected by lower melting point (102 °C), lower curing temperature (224 °C) and lower curing reaction activation energy. The investigation on the comprehensive performances of cured resin of ST-fa, coded as Poly(ST-fa), shows that Poly(ST-fa) not only has excellent thermal resistance (glass transition temperature: 325 °C; initial thermal decomposition temperature: 394 °C), but also has high tensile properties. These attractively high comprehensive properties of Poly(ST-fa) are derived from the structure with high crosslinking density and high rigidity formed by ring-opening reaction of bifunctional benzoxazine and the crosslinking of the furan group.

Ladder-like Polymer Brushes Containing Conjugated Poly(Propylenedioxythiophene) Chains.

The high stability and conductivity of 3,4-disubstituted polythiophenes such as poly(3,4-ethylenedioxythiophene) (PEDOT) make them attractive candidates for commercial applications. However, next-generation nanoelectronic devices require novel macromolecular strategies for the precise synthesis of advanced polymer structures as well as their arrangement. In this report, we present a synthetic route to make ladder-like polymer brushes with poly(3,4-propylenedioxythiophene) (PProDOT)-conjugated chains. The brushes were prepared via a self-templating surface-initiated technique (ST-SIP) that combines the surface-initiated atom transfer radical polymerization (SI-ATRP) of bifunctional ProDOT-based monomers and subsequent oxidative polymerization of the pendant ProDOT groups in the parent brushes. The brushes prepared in this way were characterized by grazing-angle FTIR, XPS spectroscopy, and AFM. Steady-state and time-resolved photoluminescence measurements were used to extract the information about the structure and effective conjugation length of PProDOT-based chains. Stability tests performed in ambient conditions and under exposure to standardized solar light revealed the remarkable stability of the obtained materials.

Solvent-driven controllable molecularly imprinted membrane with switched selectivity and fast regenerability enabled by customized bifunctional monomers

Ensuring both selective separation and fast regenerability is still a challenge, especially for long-term operation in a harsh water system. Sustainable and effective development of molecularly imprinted membranes is highly desired. Herein, we propose a type of solvent-driven controllable molecularly imprinted membranes (CS-BMIMs) to realize the switched selectivity and fast regenerability by customized bifunctional monomers. The stable supramolecular envelope interaction and hydrogen bonds between the bifunctional monomers and the phenolic hydroxyl group is introduced to regulate the selectivity of BPA. The selectivity coefficients of CS-BMIMs can reach 7.52 (αBPA/BP) and 7.97 (αBPA/HQ). Poly (ethylene glycol) unit-containing chain of dynamic solvent-responsive cross-linker drives the swelling and deswelling polymer chains to accelerate the regenerability. Significantly, BPA can be readily adsorbed into the imprinted sites in a 25% methanol (MeOH) aqueous solution with an adsorption capacity of 41.88 mg g−1 while completely desorbed in 100% MeOH following the deswelling of BPA-imprinted sites. Compared with the ordinary elution methods (VMeOH: Vacetic acid, 9: 1), the solvent-driven controllable method displayed a fast adsorption/desorption process with desirable regenerability (15 min). Moreover, the proposal of “specially designed” stimulus–response material enriches the designability and options of membrane separation in water treatment, thereby laying a foundation for developing decontamination of the water.

Catalytic hydrogenation of cardanol derived bifunctional monomers for polymerization with diesters

ABSTRACT. Cardanol extracted from cashew nut shell liquid (agro-waste) was used to synthesize a bifunctional monomer; methyl 16-(3-hydroxyphenyl)hexadecanoate using DTBPMB modified palladium catalyst. Hydrogenation of this monomer using a Ru(acac)3/triphos/MSA catalytic system in aqueous dioxane and ammonia solution gave 3-(16-hydroxyhexadecyl)phenol (75% yield) and 3-(16-aminohexadecyl)phenol (37% yield) respectively. Polymerization of 3-(16-aminohexadecyl)phenol and 3-(16-hydroxyhexadecyl)phenol with dimethyl nonadecanedioate (a di-ester obtained from methoxycarbonylation of methyl oleate) resulted into oligomers consisting of up to nine condensed monomer units (in the volatile fraction) as was revealed by MALDI-TOF MS.
 
 KEY WORDS: Cardanol, Bifunctional monomers, Catalytic hydrogenation, Polymerization
 
 Bull. Chem. Soc. Ethiop. 2022, 36(1), 173-186. 
 DOI: https://dx.doi.org/10.4314/bcse.v36i1.14 

Bio-based polybenzoxazines as an efficient coatings to protect mild steel surfaces from corrosion

New types of mono and bi-functional benzoxazine monomers were synthesized using cardanol (C) and 4-aminobenzonitrile (abn), p-phenylediamine ( ppda) along with paraformaldehyde. The synthesized benzoxazine monomers structure was elucidated by 1H, 13C-NMR and FTIR spectroscopic techniques. The polymerization temperature (Tp) of C-abn and C- ppda are noticed at 280oC and 237oC, respectively. It was also noticed that bi-functional benzoxazine (C- ppda) possesses lower curing temperature than mono-functional benzoxazine (C-abn). The ring opening polymerization of benzoxazine was confirmed by FTIR spectroscopy. Thermal analyses indicate that, benzoxazine [poly(C- ppda)] possesses higher thermal stability than poly(C-abn). The surface roughness of the benzoxazine coated MS specimen was analysed by atomic force microscope. The values of water contact angles obtained for poly(C-abn) and poly(C- ppda) are 145o and 148o, respectively. It was noticed that the mild steel specimen coated with bio-based benzoxazine C-abn exhibit excellent resistance to corrosion.

Synthesis, characterization and absorption evaluation of bifunctional monomer magnetic molecularly imprinted polymers nanoparticles for the extraction of 6-benzylaminopurine from vegetables

An adsorbent-magnetic molecularly imprinted polymers nanoparticles (MMIPs NPs) were synthesized for the extraction of 6-benzylaminopurine (6-BA) using Fe3O4 as magnetic core. The MIPs were prepared with methacrylic acid and sodium p-styrene sulfonate as bifunctional monomers. The adsorbents were characterized by transmission electron microscopy, Fourier transform infrared spectroscopy, X-ray diffractometer, thermogravimetric analysis and vibrating sample magnetometer. The adsorption properties were evaluated by static, kinetic and selective adsorption experiments. The MMIPs NPs exhibit a high adsorption capacity (37.63 mg g−1) and favorable imprinting factor (2.88) toward 6-BA. The chromatogram of 6-BA extraction using the MMIPs NPs as the adsorbent demonstrates that the matrix interference has been minimized. More importantly, MMIPs NPs can be applied to extracting 6-BA from mung bean sprout and cucumber with satisfactory recoveries (91.14–104.52%), and can be reused for at least five times. This work provides a new strategy to efficiently extract 6-BA from vegetables.

Sydnone-maleimide based cascading double 1,3-dipolar cycloaddition for synthesis of “A(A′) + B3” type hyperbranched polyimide

A new A(A′) + B3 approach to synthesizing hyperbranched polyimides (HBPIs) based on sydnone-maleimide double cycloaddition (SMDC) was investigated. N-phenylsydnone as the latent bifunctional monomer A(A′) exhibited the unique nonequal reactivity in SMDC reaction, and the irreversibly double cycloadduct was the only resultant of SMDC. Therefore, the gelation could be effectively avoided and the degree of branching (DB) was improved. The structures of HBPIs were well characterized by FT-IR, 1H NMR, 13C NMR and GPC. The effects of monomer concentration, feeding modes and molar ratios on the polymerization of HBPIs were investigated. The polymerization based on SMDC could be efficiently proceeded at relative high monomer concentration to afford HBPIs with moderate molecular weight and low polydispersity. Due to the characterics of SMDC, only the HBPIs terminated with maleimde groups could be obtained by the A(A′) + B3 approach, and they could be further modified easily. All the as-synthesized HBPIs exhibited the good solubility and thermal stability.

Polymer Stabilization of Uniform Lying Helix Texture in a Bimesogen-Doped Cholesteric Liquid Crystal for Frequency-Modulated Electro-Optic Responses.

A polymer network (PN) can sustain the uniform lying helix (ULH) texture in a binary cholesteric liquid crystal (LC) comprising a calamitic LC and a bimesogenic LC dimer. Upon copolymerization of a bifunctional monomer with a trifunctional monomer at a concentration of 5 wt% to create the desired polymer network structure, the PN-ULH was obtained with high stability and recoverability even when cycles of helical unwinding-to-rewinding processes were induced after the electrical or thermal treatment. Utilizing dielectric spectroscopy, the flexoelectric-polarization-dominated dielectric relaxation in the PN-ULH state was characterized to determine two frequency regions, f < fflexo and f > fdi, with pronounced and suppressed flexoelectric effect, respectively. It is demonstrated that the cell in the PN-ULH state can operate in the light-intensity modulation mode by the flexoelectric and dielectric effects at f < fflexo and phase-shift mode by the dielectric effect at f > fdi. Moreover, varying the voltage frequency from f < fflexo to f > fdi results in a frequency dispersion of transmittance analogous to that of flexoelectric-polarization-dominated dielectric relaxation. The unique combination of the bimesogen-doped cholesteric LC with a stable and recoverable PN-ULH texture is thus promising for developing a frequency-modulated electro-optic device.

Thermosensitive molecularly imprinted polymer coupled with HPLC for selective enrichment and determination of matrine in traditional Chinese medicine

In this study, a temperature-sensitive molecularly imprinted polymer was prepared by using the bifunctional monomer with the critical phase transition characteristics. Infrared spectrometry, scanning electron microscopy, and specific surface area testing were used to characterize the polymers. Then, the recognizing properties of the polymers were studied. Based on the prepared smart polymers, an SPE-HPLC analytical method for the determination of quinolizidine alkaloids in the extracts of Sophora flavescens was established and verified. Finally, the smart polymers were applied to the enrichment of quinolizidine alkaloids in plant extracts. By changing the temperature and solvents of the solid phase extraction conditions, the extraction process can increase the concentration of quinolizidine alkaloids by 4.3 to 5.2 folds. The extraction process has mild conditions and less time consumption, avoiding the use of a large number of toxic reagents, which indicate that the extraction process are more efficient and environmentally friendly.

Synthesis, Structure, and Dynamics of Chiral Eight-Membered Cyclic Molecules with Thienylene and Cyclopropylene Units Alternately Connected.

A rhodium(II)-catalyzed asymmetric cyclooligomerization of bifunctional monomers possessing triazolyl and vinyl groups at 2,3- and 3,4-positions on the thiophene ring is studied. Structurally interesting cyclic dimers in which thienylene and cyclopropylene units are alternately connected are obtained as the major components. The eight-membered rings in the center are non-planar and adopt a tub-shaped conformation. We also observe the phenomenon of racemization caused by a tub-to-tub ring-flipping, the activation energy of which is determined as 108 kJ mol-1 by electronic circular dichroism spectra measurement.

Enhancing the physico-mechanical properties of ethylene propylene diene monomer rubber via ץ-radiation in the presence of bi-functional and tri-functional monomers

Abstract This study, uses two polyfunctional monomers (PFMs) namely ethylene glycol dimethacrylate (EGDMA) as a bifunctional monomer and trimethylolpropane triacrylate (TMPTA) as a trifunctional monomer were used as co-agents in irradiation crosslinking of Ethylene Propylene Diene Monomer Rubber (EPDM). The effect of concentration of each PFM and irradiation dose on the crosslinking density, gel content, swelling behavior in motor and brake oils, in addition to the mechanical and thermal stability properties of EPDM was investigated in detailed. The results showed a remarkable increase in the gel content, crosslinking density and mechanical properties as the concentration of PFMs increased from 1 to 5 phr (parts per hundred parts of rubber). The various blends of EPDM with the trifunctional monomer express the highest gel content and crosslinking density than those with the bifunctional monomer. The addition of 5 phr of TMPTA to EPDM causes a dramatic improvement in tensile strength (TS) of the prepared blend reached to 188% compared to neat EPDM at 50 kGy. At the same time, the maximum TS of the blend containing 5 phr of EGDMA achieved only 41% compared to neat EPDM at an irradiation dose of 100 kGy. The swelling of irradiated samples in brake oil revealed a stronger oil resistance than motor oil. For all irradiated samples, the oil uptake decreased with the irradiation dose up to 100 kGy. The EPDM samples containing 5 phr of TMPTA recorded the highest oil resistance at 100 kGy. The results also showed that the addition of PFMs and irradiation treatment of the various prepared blends improved the thermal stability of EPDM. Finally, neat EPDM and the blends containing 1 and 3 phr of EGDMA can be used as radiation dosimeters in the very high dose range (50–200 kGy).

New bifunctional monomers from methyl vinyl glycolate.

Methyl vinyl glycolate (MVG) can be obtained by acid-catalyzed conversion of C4 and C6 sugars. Applications of MVG in polymers are so far limited to its use as co-monomer for poly(lactic acid) and as crosslinking agent. In this work, hydroformylation and methoxycarbonylation of MVG were investigated to produce novel bifunctional monomers. Polyesters with high renewable-atom content were successfully prepared and characterized.