Monomer Methyl Research Articles

Strategies for preparation of chitosan based water-soluble fluorescent probes to detect Cr3+ and Cu2+ ions

The low solubility of chitosan (CS) imposes adverse effects on its application. In this work, one of the aims is to improve the water solubility of CS. By introducing water-soluble side chains to CS, this aim was achieved. Besides, fluorescent moieties were incorporated into the side chains, the fluorescent copolymers were endowed with Cr3+ and Cu2+ ions recognition ability. Firstly, a reversible addition-fragmentation chain transfer polymerization (RAFT) reagent with naphthalimide units and CC groups was prepared. Water-soluble monomer methyl acrylic acid (MAA) was employed in the RAFT polymerization. Thus, water-soluble polymer with fluorescent unit and -C ≡ C on both ends of the polymer was obtained. They were introduced into CS, and the CS-based fluorescent copolymers were obtained eventually. The amount of MAA introduced could be tuned to obtain three side chains of different lengths. It was found that the more MAA was introduced, the better the solubility of CS-TP was. The detection limits (LOD) of Cr3+ and Cu2+ were 44.6 nM and 54.5 nM, respectively. The detection of Cr3+ and Cu2+ ions is further combined with a mobile APP to realize real-time, portable, and visual detection. And the application in the logic gate, a new detection platform, is prepared.

Self-assembled peptide-dye nanostructures for in vivo tumor imaging and photodynamic toxicity

We report noncovalent assemblies of iRGD peptides and methylene blue dyes via electrostatic and hydrophobic stacking. These resulting nanomaterials could bind to cancer cells, image them with photoacoustic signal, and then treat them via photodynamic therapy. We first assessed the optical properties and physical properties of the materials. We then evaluated their utility for live cell targeting, in vivo imaging, and in vivo photodynamic toxicity. We tuned the performance of iRGD by adding aspartic acid (DD) or tryptophan doublets (WW) to the peptide to promote electrostatic or hydrophobic stacking with methylene blue, respectively. The iRGD-DD led to 150-nm branched nanoparticles, but iRGD-WW produced 200-nm nano spheres. The branched particles had an absorbance peak that was redshifted to 720 nm suitable for photoacoustic signal. The nanospheres had a peak at 680 nm similar to monomeric methylene blue. Upon continuous irradiation, the nanospheres and branched nanoparticles led to a 116.62% and 94.82% increase in reactive oxygen species in SKOV-3 cells relative to free methylene blue at isomolar concentrations suggesting photodynamic toxicity. Targeted uptake was validated via competitive inhibition. Finally, we used in vivo bioluminescent signal to monitor tumor burden and the effect of for photodynamic therapy: The nanospheres had little impact versus controls (p = 0.089), but the branched nanoparticles slowed SKOV-3 tumor burden by 75.9% (p < 0.05).

Systematic investigations of ortho-aryl substitution effect on chain microstructure in nickel-catalyzed long chain α-olefin polymerization and copolymerization with methyl undecenoate

The tuning of branching density and branch-type distribution of the polyolefin through the ligand modification in “chain-walking”-type late transition metal catalysts is highly desired but remains a significant challenge in olefin polymerization. Herein, we performed a systematic investigation on the (co)polymerization of long chain α-olefin (1-octene and 1-decene) by a series of α-diimine Ni(II) catalysts with the varied ligand sterics arising from the number of the ortho-aryl (4-methylphenyl) substituents. The effects of structural variations, mainly including the steric tuning on the ortho-position of N-aryl ring and ligand backbone, steric distribution (ligand symmetry) tuning and electronic tuning, and polymerization conditions on catalytic activities, polymer molecular weight, polymer branching density, and branch-type distribution were described. The steric effect of ortho-methylphenyl substituents played a major role rather than the electronic effect in determining the preference of insertion fashion (1,2-insertion or 2,1-insertion) and chain walking in long chain α-olefin polymerization. As the bulk and number of ortho-methylphenyl substituents increased, the preferred 2,1-insertion and 1, ω-enchainment (chain straightening) were observed even at high monomer concentrations, thus leading to the decrease of branching density as well as the percentage of methyl branches, and eventually affording the semicrystalline “polyethylene-like” polymer with high Tm up to 121 °C and good mechanical properties. Moreover, the tuning of chain microstructure can be achieved over a very wide range through the modification of ligand sterics. Most importantly, these Ni(II) catalysts could copolymerize long chain α-olefin and polar monomer methyl undecenoate (MU) to generate the various functionalized semicrystalline copolymers with high incorporation ratios of MU up to 11% and Tm in a wide range of 5.6–93 °C.

Synthesis liquid crystal composites diacrylate resin of 2-methyl-1,4-phenylene bis(4-(3-acryloyloxy)propoxy)benzoate) with methyl methacrylate

Liquid crystal composite is a material made from monomer liquid crystal with other materials. These composites are very useful because they combine good properties of each material for many applications. Liquid crystal diacrylate resin of 2-methyl-1,4-phenylene bis(4-(3-(acryloyloxy) propoxy)benzoate) that combined with monomer methyl methacrylate (MMA) using casting solution method. Process casting solution of that material using variation weight percentage of each material. Result of casting solution was photopolymerized using preparate glass to make a thin layer polymer. Characterization thin layer polymer liquid crystal diacrylate resin with MMA using instrumentations FTIR for identify of chemical group functions molecules. FTIR spectrum showed peak at 1155 cm−1-1160 cm−1 for identifications stretching vibration of C-O-C in ester molecule and 2925-2960 cm−1 for identifying the stretching vibration of –CH3. Its band for identify bond formation between MMA with diacrylate resin. Diffractogram XRD showed thin layer polymer of PMMA-diacrylate resin has amorphous properties, because there aren’t sharp peak diffraction at 2θ 16.33°, 24.02°, 44.68°, and 72.54°. This result indicates that thin monomer methyl methacrylate blending perfect with diacrylate resin. Therefore analysis morphology of thin layer liquid crystal composite of PMMA-diacrylate resin homogen in some regions but in a little surface seen agglomeration of polymer.

The consequences of removing fluorinated compounds from rigid contact lenses

Abstract Fluorine free analogues of three commercially available rigid contact lens materials were prepared by replacing the fluorinated component, hexafluoroisopropyl methacrylate (HFPM), with the widely used, non-fluorinated monomers methyl methacrylate (MMA) and 3-methacryloxypropyltris-(trimethylsiloxy)silane (TRIS). The properties of the commercial materials and analogues were measured and compared. The oxygen permeabilities of the MMA analogues were found to be significantly lower than those of the commercial materials, decreasing by 87 % on average, while the TRIS analogues lacked sufficient hardness, dimensional stability and lipid deposit resistance to be viable for use in rigid contact lenses. Analogues prepared using a 1:1 mixture of MMA and TRIS had the best overall combination of properties, but were still on average 47 % less permeable to oxygen and also significantly less resistant to lipid deposition. The analogues prepared in this study did not adequately replicate the performance of marketed, fluorine containing rigid contact lens materials. These observations give an indication of the challenges that would face contact lens material manufacturers in preparing rigid lens polymers without the use of fluorinated species. A reduction in effectiveness would be almost inevitable, and would be expected to have a negative impact on the safety and eye health of rigid contact lens patients.

Development of a fluorescent PMMA-based polymer material through in-situ incorporation of curcuma extract

In the present work, the in situ incorporation of curcumin was carried out in a polymer matrix through bulk polymerization to improve its photostability. It was found that extraction of curcumin from turmeric extract by the precursor monomer methyl methacrylate (MMA) can be performed immediately before the polymerization in order to reduce the degradation of the fluorescent species by the initiator system, although the obtained results also showed that incorporation of the turmeric extract into monomer can retard the polymerization kinetics. Despite that, the fluorescence properties of curcumin were preserved after incorporation in a solid polymeric matrix, which also enhanced the fluorophore photostability, avoiding the rapid degradation of the fluorophore observed when it is dispersed in solvents. Furthermore, it was also observed that addition of acrylic acid (AA) as a comonomer enhanced the photochemical stability of the turmeric extract incorporated into the polymer matrix and promoted the bathochromic effect, when compared to the spectroscopic behavior of the extract obtained from MMA, both in solution and solid state. It was possible to optimize the synthesis condition with help of a standard factorial experimental design, allowing the simultaneous attainment of high monomer conversion and fluorescence properties of the obtained material.

Effects of low temperatures and high strain rates on the tensile properties of polyurethane polymers for adhesives

ABSTRACT The mechanical properties of polyurethane compounds were experimentally investigated by changing the composition of their components. Polyol components (polyoxypropylene glycol: PPG, polyoxytetramethylene glycol: PTMG, and polycarbonatediol: PCD) were mixed with monomeric methylene diphenyl diisocyanate to synthesize polyurethane pre-polymer, mixed with chain extenders (1,4’-butanediol: 1,4’-BD or dimethylthiotoluene diamine: DMTDA), and cured, to prepare four types of polyurethane resins. Tensile tests were conducted using a mechanical testing machine with a strain rate of approximately 0.3 s−1 and a hydraulic high-speed tensile testing machine with a strain rate of approximately 500 s−1. The temperature was controlled to be −40°C, −10°C, or 25°C. When PTMG was used as the polyol, the stress-strain relationship was less sensitive to temperatures and loading rates, and the material properties exhibited a relatively good balance between elongation and strength. Additionally, the use of 1,4’-BD as a chain extender resulted in higher elongation and lower strength than the use of DMTDA. Conversely, the stress-strain relationship was dramatically altered by the test conditions when PPG and PCD were used as the polyol and embrittlement under a combination of low temperature and high strain rate was confirmed. Furthermore, there were certain compositional combinations that exhibit necking at low temperatures.

Zeolite Y hydrolyses methyl methacrylate to methacrylic acid in the gas phase

Poly(methyl methacrylate) (PMMA) depolymerizes to its monomer methyl methacrylate (MMA) below 400 °C but the accompanying byproducts have similar boiling points, which incurs excessive separation costs rendering the process economically challenging. Hydrolyzing MMA to methacrylic acid (MAA) is an economic alternative since its boiling point is 61 °C higher. Zeolites are among a class of heterogeneous catalyst with Brønsted acidity that protonate the ester carbonyl group in the much less common gas-phase route to acids. Here, for the first time, we report the hydrolysis kinetics of MMA to MAA in the gas phase over a Y/SiO2 zeolite with a 960 m2 g−1 surface area. MMA conversion in an 8 mm fixed bed reactor averaged 94 % above 200 °C and a yield of 85 %. Operating the reactor in excess water vapour shifts the equilibrium conversion towards the products. Surface reaction between adsorbed MMA and water is the rate controlling step. Heterogeneous supports control the hydrophobic properties, and thereby activity and stability. Introducing zeolites in the matrix of a silica gel facilitates access to all external zeolite active sites compared to spray-drying with Ludox where the SiO2 shell covers the external catalyst surface. Nuclear magnetic resonance spectroscopy with magic angle spinning (MAS NMR) and ultra-violet visible (UV–vis) detected Brønsted acidity. The reaction rate is first order in methacrylic acid and water and the equilibrium conversion is about 95 % above 200 °C. The apparent activation energy was 106 kJ mol−1.

The Bone Cement Hypercoagulation Syndrome: Pathophysiology, Mortality, and Prevention.

Since Charnley introduced acrylic cement to seal metallic hip prostheses in the 1950s, reports of perioperative fatal cardiorespiratory and vascular dysfunctions have been published. Studies on humans and animals have shown neurogenic stimulation and substantial local and systemic activation of coagulation are caused by surgical bone marrow damage and chemical cell destruction by toxic monomeric methyl methacrylate from the implanted cement and other tissue-released substances. Venous blood-borne cell fragments and conjugates of activated cells from the surgical site are sequestered and trapped in the pulmonary microcirculation. A substantial hypercoagulation occurs in the lung circulation. Hypercoagulable blood is passed over to the arterial side and may cause vessel obliteration and organ damage. This process may affect the brain, heart, and kidneys and, through the release of vasoactive substances, introduce hemodynamic imbalances that can lead to fatal outcomes in susceptible populations such as elderly patients with hip fractures. The main underlying pathophysiologic processes leading to these occasionally devastating outcomes are a substantial activation of coagulation and cell destruction caused by the toxic substance released by curing bone cement and several vasoactive substances.

Side-Chain-Type High Dielectric-Constant Dipolar Polyimides with Temperature Resistance.

Innovative dielectric materials with high-temperature resistance and outstanding dielectric properties have attracted tremendous attention in advanced electronical fields. Polyimide(PI) is considered a promising candidate for the modern electronic industry due to its excellent dielectric properties and comprehensive properties. However, the limited-adjustable range of dielectric constant and the difficulty to obtain a high dielectric constant restrict the application of PI as high dielectric materials. Herein, a novel diamine monomer (2,2'-bis((methylsulfonyl)methyl)-[1,1'-biphenyl]-4,4'-diamine (BSBPA)) containing a rigid biphenyl structure and high dipolar sulfonyl pendant groups is designed for high dielectric polyimides. The rigid biphenyl and polar sulfonyl pendant groups can reasonably optimize the molecular structure and orientational polarization of polyimides to improve their dielectric properties and thermal properties. Moreover, the effect of different bridge linkages on the dielectric properties is studied by using the different dianhydrides. Thus, the PI-BSBPA films especially the DSDA-BSBPA film (DSDA: 3,3',4,4'-diphenylsulfonetetracarboxylic dianhydride)achieve great thermal properties (T5%d of 377°C and Tg of 358°C) and excellent dielectric properties (6.95 at 1kHz) along with high discharged energy density of 5.25Jcm-3 and charge-discharge efficiency of 90%. The collaborative control of main-chain and side-chain engineering is effective to endow the polyimides with high-temperature tolerance and high dielectric performance.

Synthesis, characterization and investigation of fluorescent Sn2+ probe potential of pyrene-derived monomer and its oligo(azomethine) compound

A monomer (2-methoxy-6-((pyren-1-yl-imino)methyl)phenol, VP) was synthesized by the Schiff base reaction of o-vanillin (VA) and 1-aminopyrene (AP), and an oligomer (oligo-2-methoxy-6-((pyren-1-yl-imino)methyl)phenol, OVP) was synthesized from this monomer via oxidative polycondensation reaction. The structural characterization of the obtained monomer and oligomer by FT-IR, 1H NMR and 13C NMR; electrochemical properties with cyclic voltammetry (CV); optical properties with UV–Vis and photoluminescence (PL) spectroscopy; thermal stability with thermogravimetric analysis (TGA); and the molecular weight of the oligomer were determined by gel permeation chromatography (GPC). From the fluorescence titration, VP was found to be sensitive to Sn2+ out of a range of metal ions. When the VP solution, to which 1 equivalent amount of Sn2+ was added, was excited with 320 nm light, it was observed that it emits bright blue color at 445 nm. It was found that VP, whose limit of detection (LOD) was calculated as 4.24 nM for Sn2+, had a sensitive and selective fluorescence sensor potential. In addition, it was found that the obtained oligo[2-methoxy-6-((pyren-1-yl-imino)methyl)phenol] (OVP) had a molecular mass of 3450 Da and showed fluorescent properties. The maximum emission of the OVP excited with 380 nm light was observed at 443 nm, with green emission.

Poly(ionic liquid) materials tailored by carboxyl groups for the gas phase-conversion of epoxide and CO2 into cyclic carbonates

Carbon dioxide (CO2) is an important C1 resource, and the preparation of cyclocarbonate by catalyzing CO2 and epoxides is a nature-friendly route to utilize. In this study, polymer ionic liquid materials (PILMs) were prepared by copolymerizing the vinylimidazole-based ionic liquids (ILs) as monomer with carbonyl-rich copolymer monomer methyl methacrylate (MMA) and crosslinking agent ethylene glycol dimethacrylate (EGDMA), to enhance the affinity of PILMs for CO2 and PO. Then, epoxides and CO2 were converted to cyclic carbonates using PILMs by the gas-liquid reaction (GLR) and the gas phase-conversion progress (GCP). Amongst those polymer ionic liquid materials, the PILM containing carboxypropyl group (PILM-VCPImBr) exhibited the performance with the propylene carbonate (PC) yield of 96.7% (at 130 °C, 3 MPa CO2, reaction time 3 h) by GLR. And the yield of PC reached 94.2% (at 130 °C, 2 MPa CO2, reaction time 3 h) by GCP, which was the same as that of GLR. The excellent catalytic activity can be attributed to the fact that the PILMs fully dispersed the active sites and were rich in pores, which could effectively catalyze propylene oxide (PO) and CO2 to generate PC. Finally, 1H NMR spectra showed that VCPImBr and PO formed strong hydrogen bonds to participate the ring-opening process of epoxides, and a possible catalytic mechanism of H-bond synergistic effect was proposed. This article provides a novel strategy for designing both stable and nature-friendly catalysts in the CO2 transformation, and proposes a new method for cyclic carbonate conversion.

Effective Immobilization of Monomeric Methylene Blue on Hydroxyapatite Nanoparticles by Controlling Inorganic-Organic Interfacial Interactions.

We successfully synthesized methylene blue (MB+)-immobilized hydroxyapatite (HM) nanoparticles by changing the initial P/Ca molar ratio. The immobilized amount of MB+ increased with increasing the initial P/Ca molar ratio from 0.6 to 4.0, and the HM had an elliptical shape (long length, 21-24 nm; short length, 11-13 nm) irrespective of the initial P/Ca molar ratio. Upon increasing the initial P/Ca molar ratio, the number of carbonate ions on the HM surface decreased, which would be owing to the electrostatic repulsion by the surface phosphate ions (i.e., P-O-), the surface P-OH mainly dissociated to form P-O-, and the electrostatic interaction of P-O- with MB+ enhanced. The bonding of MB+ with surface P-OH and Ca2+ sites of hydroxyapatite would be hydrogen-bonding and Lewis acid-base interactions, respectively. The optimum synthesis condition for MB+ immobilization at the monomer state was found to be the initial P/Ca molar ratio of 2.0. Here, the existence percentage of the MB+ monomer and the molecular occupancy of the surface carbonate ion at the initial P/Ca molar ratio of 2.0 were higher than those at 4.0 with no significant difference in the immobilized amount of MB+, indicating that MB+ at the initial P/Ca molar ratio of 4.0 is more aggregated than that at 2.0. These results suggested that a part of carbonate ions has a role as a spacer to suppress MB+ aggregation. Accordingly, the interfacial interactions between the MB+ monomer and the hydroxyapatite surface were clarified, which can effectively be controlled by the initial P/Ca molar ratio. These findings will provide fundamental and useful knowledge for the design of calcium phosphate-organic nanohybrids. We believe that these particles will be the base materials to realize diagnostic and/or therapeutic functions through the molecular state control by optimizing the synthesis conditions.

A monomeric (trimethylsilyl)methyl lithium complex: synthesis, structure, decomposition and preliminary reactivity studies.

Monomeric organolithium (LiR) complexes could provide enhanced Li-C bond reactivity and suggest mechanisms for a plethora of LiR-mediated reactions. They are highly sought-after but remain a synthetic challenge for organometallic chemists. In this work, we report the synthesis and characterisation of a monomeric (trimethylsilyl)methyl lithium complex, namely [Li(CH2SiMe3)(κ3-N,N',N''-Me6Tren)] (1), where Me6Tren is a tetradentate neutral amine ligand. The structure of 1 was comprehensively examined by single-crystal X-ray diffraction, variable temperature NMR spectroscopy and electron absorption spectroscopy. Complex 1 decomposes via ligand C-H and C-N activations to produce a Li amide complex 2. Preliminary reactivity studies of 1 reveal CO insertion and C-H activation reaction patterns.

PHOTOPOLYMERIZATION OF MONOMER METHYL METHACRYLATE (PMMA) WITH INDIUM TIN OXIDE (ITO) NANOPARTICLE AND MODIFICATIONS BY POLYETHYLENE-BLOCK-POLYETHYLENE GLYCOL (PE-BPEG) USING UV CURING TECHNOLOGY

Photopolymerizations of monomer methyl methacrylate being nanocomposite have been widely carried out because it has the advantage that it can improve the properties of the materials used. The purpose of this research was to study the synthesized characteristics of PMMA+ITO and PMMA+ITO+PE-b-PEG using the UV Curing method. The nanocomposites were synthesized with a variation of ITO concentrations were 5% w/t, 10% w/t, and 15% w/t. The characterization group functions using FTIR spectroscopy showed the loss of absorption peaks at wave numbers 3100 cm-1 and 1670 cm-1 at PMMA. The results of XRD characterization showed that effect addition of PE-b-PEG, peaks appeared around the 2θ 19°-28° area which was a typical peak for PE-b-PEG. the nanocomposite is an amorphous phase still dominated. Value of conductivity of nanocomposite PMMA addition of ITO with a concentration of 15% resulted in a nanocomposite with the highest conductivity value of 6.4068 x 10-7 S/m

Methylaluminum complexes based on tridentate 2,6-bis(mercaptoalkyl)pyridine SNS-ligands

New SNS-ligands were obtained by consequent ring-opening of substituted thiiranes by lithiated 2,6-lutidine, mono- functionalized SN-ligands having been isolated as the intermediate compounds. The molecular structure of ligand 2,6-Py(CH2CH2CBn2SH)2 was elucidated by XRD analysis.The reaction of AlMe3 with SNS-ligands afforded monomeric methyl aluminum complexes which have been tested in ring- opening polymerization of ε caprolactone in bulk.

Synthesis and characterization of Ag-decorated litchi-like porous Cu/Cu2O micro/nanoparticles with antibacterial activity

ABSTRACT Efficient and stable inorganic antibacterial material is highly spotted in antibacterial materials. However, the morphology and grain diameter of conventional inorganic compound antibacterial agent carrier are difficult to control and severely deteriorate antibacterial properties. In this research, using diethylene glycol monomer methyl ether as a pore-forming agent, litchi-like porous micro/nano Cu/Cu2O composite antibacterial carriers (Car-MNps) with good dispersion and high crystallinity are prepared by a liquid-phase chemical reduction process. Subsequently, we develop a synergistic system of inorganic composite antibacterial materials decorated with silver (Ag/Car-MNps). The microstructures of the antibacterial materials are characterized by means of various techniques, such as X-ray diffraction, scanning electron microscope, transmission electron microscope, X-ray photoelectron spectroscopy, and nitrogen adsorption. The antibacterial activities are evaluated by methods of bacteriostatic zone and minimum inhibitory concentration (MIC). The results show that the micro- and nano-materials of Car-MNPs exhibit high specific surface area characteristics and show attractive bactericidal properties. The MIC values of Ag/Car-MNps against S. aureus and E. coli decrease from 1000 mg/L and 2000mg/L to 125 and 250 mg/L, respectively, in comparison with those of Car-MNps. Our experiments may show novel insights for the development of inorganic compound antibacterial agents.

Synthesis of Mono Ethylene Glycol (MEG)-Based Polyurethane and Effect of Chain Extender on Its Associated Properties.

This study depicts the investigations of the effect of composition of aromatic polyester polyol produced from terephthalic acid (TPA) and different concentrations of mono ethylene glycol (mEG) as a chain extender on the mechanical properties of polyurethane (PU) elastomer. Aromatic polyester polyols are prepared via the poly-esterification of adipic acid, terephthalic acid, catalyst, and mono ethylene glycol; while a polyurethane elastomer is formulated via the pre-polymerization of polyol with pure monomeric Methylene diphenyl diisocyanate (MDI.) Mechanical properties of polyurethane elastomers are examined, such as hardness via shore A hardness, apparent density via ASTM (American Society for Testing and Materials) D1622–08, and abrasion wear resistance via a Deutches Institut fur Normung (DIN) abrasion wear resistance tester. Structural properties are investigated through Fourier-transform infrared spectroscopy (FTIR) analysis. Results reveal that the shore A hardness of the PU elastomer increases with an increasing concentration of mEG from 4g to 12g. Nevertheless, the elastomer’s density depicts a reduction with an increasing extender content. The abrasion wear resistance of polyurethane, however, increases with an increasing concentration of glycol. A structural analysis through FTIR confirms the formation of polyurethane elastomer through the characteristic peaks demonstrated.

Zinc‐Catalyzed Chemical Recycling of Poly(ϵ‐caprolactone) Applying Transesterification Reactions

AbstractThe chemical recycling of poly(ϵ‐caprolactone) (PCL) was explored based on depolymerization and polymerization. The concept bases on the zinc‐catalyzed depolymerization via methanolysis to produce methyl 6‐hydroxyhexanoate, which is polymerized in a zinc‐catalyzed condensation reaction to generate new PCL and close the cycle. In more detail, with zinc(II) acetate as catalyst, PCL was depolymerized with turnover frequencies of up to 468 h−1 using microwave heating. On the other hand zinc(II) acetate was also able to catalyze the polymer formation using the monomer methyl 6‐hydroxyhexanoate. PCL was obtained in good yield and Mn ∼1729 g/mol and Mw ∼5823 g/mol were achieved.

Influence of chiral monomer concentration on thermo-optical properties of glass-forming cyclic siloxane side chain liquid crystal oligomers

ABSTRACT A series of new cyclic siloxane side-chain liquid crystal oligomers containing chiral (-)-menthyl monomer (M1) and achiral benzene methyl ester monomer (M2), denoted as O1–O4, were successfully synthesised. Their chemical structures were confirmed by FT-IR and 1H NMR spectra. Phase transition behaviours and phase structures were investigated by differential scanning calorimetry (DSC) and polarised optical microscopy (POM). Bragg-selective reflection spectra were measured by ultraviolet/visible spectrometer (UV/Vis). The glassy oligomers with bright colours at room temperature were obtained by thermal quenching treatment with liquid nitrogen (liquid Nr). The reflection colours were adjusted into visible light region by adjusting the chiral monomer content (X M1* ) in oligomers. The glassy oligomers have shown good thermal stability at room temperature for more than 1 year.