Thermal Properties Of Copolymers Research Articles

Ethylene Copolymerization with Linear and End-Cyclized Olefins via a Metallocene Catalyst: Polymerization Behavior and Thermal Properties of Copolymers

Olefin solution polymerization can be used to obtain high-performance polyolefin materials that cannot be obtained via other polymerization processes. Polyolefin elastomers (POE) are a typical example. Due to cost, only a few linear α-olefins (e.g., 1-butene, 1-hexene, and 1-octene) are used as comonomers in solution polymerization in industry. However, α-olefin comonomers with other structures may have different effects on polymerization in comparison with common linear ones. Moreover, the properties of the corresponding materials may differ significantly. In this work, copolymers of ethylene with linear and end-cyclized α-olefins are synthesized using a metallocene catalyst. The copolymerization of ethylene with linear α-olefins results in a higher turn-over frequency (TOF) and lower incorporation than copolymerization with end-cyclized α-olefins, which may indicate that end-cyclized α-olefins have a higher coordination probability and lower insertion rate. In this reaction, the comonomer is distributed randomly in the polymer chain and efficiently destroys crystallization. End-cyclized α-olefins exhibit a much stronger crystallization destructive capacity (CDC) in the copolymer than linear α-olefins, possibly because linear α-olefins act mainly in the radial direction of the main chain of the polymer, while end-cyclized α-olefins act mainly in the axial direction of the main chain.

Study on the Preparation and Optical Properties of Co‐polycarbonates Based on Binaphthalene and Cardo Structures

AbstractCopolymer carbonate was synthesized from diphenyl carbonate (DPC), 9, 9‐bis [3‐phenyl‐4 ‐(2‐hydroxyethoxy) phenyl] fluorene (BPPEF) and 2,2′ ‐bis (2‐hydroxy‐ethoxy)‐1,1′ ‐binaphthalene (BHEBN) by melt transesterification. The composition and random structure of the copolymer were determined by FT‐IR, 1H NMR and 13C NMR analysis. DSC and TGA analysis showed that Cardo structure could significantly increase the glass transition temperature and thermal decomposition temperature. With the addition of BHEBN, the refractive index of copolymer was increased, but the thermal properties of copolymer were decreased. It is found that the contribution of naphthalene structure to the refractive index of the polymer material is higher than that of benzene structure. When the dosage of BHEBN is 42 mol %, the glass transition temperature (Tg) of the copolymer is 141.8 °C, the maximum thermal decomposition temperature is 421.9 °C, the refractive index is 1.6535, the Abbe number is 21, the transmittance is 88.29 %, and the birefringence is negative 0.01×10−3.

Preparation and identification of green polymers towards the production of sustainable latex from β-myrcene and some methacrylate monomers

Sustainable polymers have enough potential to overcome petroleum materials and not completely rely on them for the presence of renewable raw materials, as well as the possibility of developing polymerization methods for renewable raw materials to have these materials recyclability, biodegradability and being a non-toxic material. This has been the focus of recent years. Solvent-free emulsion copolymerization of β-myrcene, a naturally occurring monoterpene monomer, the co-monomers that were used with β-myrcene, tetrahydrofurfuryl methacrylate, iso-bornyl methacrylate, and tert-butyl methacrylate, and each methacrylate monomer was polymerized separately with β-myrcene monomer, β-myrcene –methacrylate monomer (MY/MA) copolymers of different compositions were synthesized under nitrogen atmosphere at 60 ºC, using copolymers composition 50/50 comonomer reactivity ratios, and has been added sodium dodecyl sulfate as emulsifier, and ammonium persulfate as initiator. 1H-NMR, 13CNMR and FTIR spectroscopy were used to confirm the chemical structure and composition. It was found that the copolymerization reaction of each copolymer is influenced with the form of the methacrylate(s) side chain. Furthermore, the thermal properties of copolymers were characterized by DSC and TGA, where the value Tg indicate that random composition copolymers, due to the difference in crystallization of each side chain.

Physicochemical properties of graft copolymers of collagen and fibroin with polyacrylic acid

Certain physicochemical properties of the synthesized graft copolymers of raw skin collagen and natural silk fibroin with polyacrylic acid have been determined. The dependence of the solubility, density, and thermal properties of copolymers on the ratio of components and synthesis conditions has been established.

Terpolymers of Acrylonitrile, Acrylic Acid, and Alkyl Acrylates: Effect of Alkyl Acrylate on the Thermal Properties of Copolymers

Terpolymers of Acrylonitrile, Acrylic Acid, and Alkyl Acrylates: Effect of Alkyl Acrylate on the Thermal Properties of Copolymers

Effect of Catalyst Type on the Copolymerization of Styrene/1-Hexene and Exploring of Their Structural and Thermal Properties

The effect of catalyst type on styrene/1-hexene copolymerization reactions was investigated. The copolymerization reactions were performed using conventional free radical polymerization, atom transfer radical polymerization (ATRP) and Ziegler-Natta polymerization methods. Copolymers containing different 1-hexene compositions were synthesized and characterized by 1H NMR, GPC and DSC methods. The monomer reactivity ratios for free radical copolymerization were calculated using linear methods and found to be r1 ~ 25 and r2 → 0 for styrene and 1-hexene, respectively. The increases of 1-hexene mole fraction in ATRP synthesized copolymers showed that CuCl/L promotes 1-hexene cross propagation significantly. Furthermore, 1-hexene cannot participate in self-propagation reaction. In the polymerization assisted by supported Ziegler-Natta catalyst, the conversion of the reaction was increased with mole fraction of 1-hexene in the feed, which indicated the higher reactivity of this monomer. Finally, the thermal properties of copolymers were studied by DSC.

Statistical copolymerization of N-vinyl-pyrrolidone and alkyl methacrylates via RAFT: reactivity ratios and thermal analysis

The synthesis of statistical copolymers of N-vinylpyrrolidone (NVP) with the alkyl methacrylates: hexyl methacrylate (HMA) and stearyl methacrylate (SMA), is conducted by reversible addition-fragmentation chain transfer polymerization (RAFT), employing [(O-ethylxanthyl) methyl]benzene and [1-(O-ethylxanthyl) ethyl]benzene as the RAFT agents. The reactivity ratios are estimated using the Fineman-Ross, inverted Fineman-Ross, Kelen-Tudos and Barson-Fenn graphical methods as well as the computer program COPOINT, modified to both the terminal and the penultimate model. In all cases, the NVP reactivity ratio is significantly lower than that of the methacrylates. Structural parameters of the copolymers are obtained by calculating the dyad and triad sequence fractions and the mean sequence length. The thermal properties of the copolymers are studied by Differential Scanning Calorimetry and Thermogravimetric Analysis, and the results are compared with those of the respective homopolymers. In spite of the relatively small amount of NVP in the copolymers, copolymer thermal properties are influenced by both monomers.

Effect on electrospun fibres by synthesis of high branching polylactic acid.

Polylactic electrospun porous fibres have been widely used in tissue engineering scaffolds. However, the application of linear polylactic is limited due to its poor hydrophilicity, which leads to phase separation and has been seldom used in porous fibre preparation. Instead, branching polylactic acts as a new effective method to prepare porous fibres because it can increase polylactic polar property and make it easy to be formulated in the following application. In the current study, we prepared an ultra-high molecular weight of high branching polylactic with glycerol as the initiator by controlling the ring-opening polymerization time, adding amount of catalyst and glycerol. The structure, molecular weight and thermal properties of copolymers were tested subsequently. The result showed that the surface of the high branching polylactic films is smooth, hydrophilic and porous. This branching polylactic formed electrospun porous fibres and possessed a strong adsorption of silver ion. Our study provided a simple and efficient way to synthesize branching polylactic polymer and prepare electrospun porous fibres, which may provide potential applications in the field of biomaterials for tissue engineering or antibacterial dressing compared with the application of linear polylactic and 3-arm polylactic materials.

Synthesis and photoluminescence properties of co‐polyamides with anthrazoline‐containing units in the main chain

A series of anthrazoline-containing monomers are synthesized, and eight co-polyamides of different chemical structures, containing 1,9-anthrazoline fragments in the main chain, are obtained and investigated. Photoluminescent, stress-strain, and thermal properties of these polymers are studied. It is shown that polymers with fragments of 4,4'-(pyrido[3,2-g]-quinoline-2,8-diyl)dianiline and 4,4'-(10-methylpyrido[3,2-g]quinoline-2,8-diyl)dianiline possess an intense luminescence in the range 550-650nm. The performed investigations made it possible to determine the effect of substituents of various natures in the anthrazoline cycle and the position of amide group (meta- and para-configurations) on optical, stress-strain, and thermal properties of copolymers, opening up a prospect for further developments of principles of design of polymers with optimal characteristics.

Organic Catalysis for Ring-Opening Graft Polymerization of p-Dioxanone with Xylan in Ionic liquid.

Recently, organic catalysis has become a powerful alternative to the use of more traditional metal-based catalysts. In this study, 4-dimethylaminopyridine (DMAP), 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), and 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) were applied to mediate the ring-opening graft polymerization (ROGP) of p-dioxanone (PDO) with xylan-based hemicelluloses in ionic liquid 1-butyl-3-methylimidazolium chloride ([Bmim]Cl). Excellent control of the molar ratio of the catalyst to anhydroxylose units (AXU) in xylan was found for a good tuning of the weight percent gain (WPG) of xylan-graft-poly(p-dioxanone) (xylan-g-PPDO) copolymers. As a result, the maximum WPG of xylan-g-PPDO copolymers was 431.07% (DMAP/AXU of 2/1), 316.72% (DBU/AXU of 0.2/1), and 323.15% (TBD/AXU of 0.2/1), respectively. The structure of xylan-g-PPDO copolymers was characterized with FT-IR and NMR. The thermal properties of copolymers were investigated using thermogravimetric analysis (TGA/DTG) and differential scanning calorimetry (DSC), and a significant difference was observed regarding the transition temperature (Tg), melting temperature (Tm), and crystallization temperature (Tc).

Block copolymerization of methylmethacrylate via ATRP method using a macroinitiator produced by ring opening polymerization: Characterization, dielectric properties, and a kinetic investigation

ABSTRACTPoly(2-(3-methyl-3-phenylcyclobutyloxirane-co-ϵ-caprolactone) [P(PCBO-co-ϵ-CL)] was synthesized by ring opening polymerization (ROP) of 2-(3-methyl-3-phenylcyclobutyloxirane and ϵ-caprolactone (ϵ-CL) using benzyl alcohol as the initiator and Sn(Oc)2 as the catalyst. To produce a macroinitiator from copolymer with hydroxyl end group was carried out reaction of acylation with choloroacetyl chloride. The molecular structures of copolymers were confirmed by FT-IR, 1H-NMR spectroscopies and gel permeation chromatography (GPC). A kinetic series of methyl methacrylate (MMA) via ATRP method were studied in the presence of this macroinitiator and using CuBr/2,2′-bipyridine (bpy) as catalyst at 110°C. The kinetic study showed that the polymerization proceeded in a controlled way up to high conversions and the number-average molecular weight (Mn) increased depending on time. The thermal properties of copolymers were evaluated by TGA and DSC measurements. The temperature and frequency dependence of dielectric constant (έ) and dielectric loss factor (ϵ″) of P[(PCBO-co-ϵ-CL)-b-PMMA] and that of doped with different concentration of EuCl3 were investigated between the frequency of 100–2000 Hz and temperature range (300–430 K). Also, the ac conductivity has been measured to see the effect of frequency and temperature.

Poly(methyl methacrylate-co-butyl acrylate-co-acrylic acid): Physico-chemical characterization and targeted dye sensitized solar cell application

A random poly(methyl methacrylate-co-butyl acrylate-co-acrylic acid) [P(MMA-co-BA-co-AA)] was synthesized via emulsion polymerization utilizing thermally-activated persulfate radicals. The successful synthesis of high molecular weight copolymer at high monomer conversion rate was confirmed by NMR study. Various techniques were employed to characterize the structure, electrical and thermal properties of copolymer. The removal of unreacted monomers from the end product by casting technique was rationalized from the disappearance of CC FTIR characteristic peak in the cast film. The drying of the emulsion above the glass transition temperature (Tg=24°C) yields an amorphous film with smooth surface morphology. The suitability of the formed continuous film as a base polymer for iodide-based electrolytes in dye sensitized solar cell (DSSC) fabrication was investigated. The polymeric solid state electrolytes (PSSE) were formulated by varying the doping concentrations of sodium iodide (NaI) in fixed ratio of iodine (I2) and mixtures of ethylene carbonate: propylene carbonate (EC:PC, 1:1). The DSSC fabricated using PSSE with 15wt.% NaI showed the highest solar-to-electrical energy conversion efficiency (η) of 3.22% under 100mWcm−2 sunlight intensity. This implies that the physico-chemical properties of the synthesized copolymer are suitable for the development of photoelectrochemical device.

Role of aliphatic hydrocarbon content in non-solvating porogens toward porosity of cross-linked microbeads

Megaporous spherical acrylate copolymer beads were synthesized by suspension polymerization using non-solvating porogens. Non-solvating porogens with higher aliphatic hydrocarbon content generated megaporous morphology with lower surface area. Surface area increased and inversely megaporosity was decreased with decrease in the aliphatic hydrocarbon content of porogen. Megaporosity (5.47 μm) and pore volume of 5.52 cm3/g was obtained with n-decanol. Thermal property of copolymer is a function of type (rigidity/flexibility/elemental composition) and concentration (cross-link density) of monomer and cross-linker. Copolymer containing rigid cross-linker (divinylbenzene) had better thermal stability over copolymer with flexible cross-linker (ethylene dimethacrylate). Further, higher concentration of rigid cross-linker or lower concentration of flexible cross-linker enhanced the thermal stability. Porous polymers are potentially recognized as a solid support for solid-phase synthesis.

Preparation of scale inhibitor by using the waste of refined 2‐acrylamido‐2‐methylpropane sulfonic acid

Acrylic acid‐2‐acrylamido‐2‐methylpropane sulfonic acid (AA‐AMPS) is a kind of copolymer with good scale and corrosion inhibition performance. Refining of AMPS produces refined residue, which belongs to hazardous waste and must be properly treated and disposed. In this work, the refined residue was reused as the raw material to synthesize scale inhibition copolymer with the addition of AA. The chemical construction and thermal properties of copolymers were confirmed by NMR, FTIR, and thermogravimetry analysis (TGA). To achieve a comprehensive and systematic understanding of copolymers, the inhibition behavior of CaCO3, Ca3 (PO4)2, and CaSO4 were examined through static scale inhibition tests. The capability of ferric oxide dispersion was also determined. The results of structural analysis were consistent with the expected structures. Static experiments were observed that scale inhibition of Ca3 (PO4)2 and CaSO4 was excellent and the scale inhibition rate was close to 100% when the concentration of AA‐AMPS was 30 mg L−1. It was noticed that the performance of copolymers synthesized with AMPS residue appeared nearly no different than when AA‐AMPS was synthesized with normal materials. The results show that the refined AMPS residue could be reused as raw material to prepare scale inhibitor copolymer.Significance: Refined residue of AMPS was used to synthesize scale inhibition copolymer in this work. It would bring serious damage to society and environment if the hazardous waste refined residue cannot be properly treated and disposed. This study shows that the reuse of refined residue could achieve the goals of making use of waste and save the resources. This reuse technology develops a new way to reuse the hazardous waste and it would provide both economical and environmental benefits. © 2016 American Institute of Chemical Engineers Environ Prog, 35: 833–839, 2016

Synthesis and Characterization of Polycarbonate Copolymers Containing Benzoyl Groups on the Side Chain for Scratch Resistance

The purpose of this study was to enhance the scratch resistance of polycarbonate copolymer by using 3,3′-dibenzoyl-4,4′-dihydroxybiphenyl (DBHP) monomer, containing benzoyl moieties on the ortho positions. DBHP monomer was synthesized from 4,4′-dihydroxybiphenyl and benzoyl chloride, followed by the Friedel-Craft rearrangement reaction with AlCl3. The polymerizations were conducted following the low-temperature procedure, which is carried out in methylene chloride by using triphosgene, triethylamine, bisphenol-A, and DBHP. The chemical structures of the polycarbonate copolymers were confirmed by1H-NMR. The thermal properties of copolymers were investigated by thermogravimetric analysis and differential scanning calorimetry, and also surface morphologies were assessed by atomic force microscopy. The scratch resistance of homopolymer film (100 μm) changed from 6B to 1B, and the contact angle of a sessile water drop onto the homopolymer film also increased.

Exploiting a new glycerol-based copolymer as a route to wound healing: Synthesis, characterization and biocompatibility assessment

The use of biocompatible materials based on naturally derived monomers plays a key role in pharmaceutical and cosmetic industries. In this paper we describe the synthesis of a new low molecular weight copolymer, based on glycerol and l-tartaric acid, useful to develop biocompatible dermal patches with drug delivery properties. The copolymer's chemical composition was assessed by FT-IR (Fourier transform infrared spectroscopy), 1H NMR (1H Nuclear Magnetic Resonance) and XPS (X-ray photoelectron spectroscopy), while its molecular weight distribution was estimated by SEC (size exclusion chromatography). Copolymer thermal properties were studied by TGA (thermogravimetric analysis). Biological evaluations by MTT assay and SEM (scanning electron microscopy) observations performed with murine fibroblasts and human keratinocytes (HaCaT) revealed a good compatibility of the proposed copolymer. Ciprofloxacin was selected as model drug and its release was evaluated by HPLC (high performance liquid chromatography), showing that the new copolymer supplied promising results as drug delivery system for wound healing applications. Furthermore, investigations on Skin-Mesenchymal stem cells (S-MSCs) behaviour and gene expression showed that the copolymer and its combination with ciprofloxacin did not affect their stemness. In this regard, the fabrication of dermal patches with new, low cost materials for local treatment of skin infections represents an attractive strategy in order to bypass the worrying side effects of systemic antibiotic therapy. Overall, the performed physico-chemical characterization, drug release test and biological evaluations showed that this new copolymer could be a promising tool for the in situ delivery of bioactive molecules during skin lesions treatment.

Crystallization and Thermal Properties of PLLA–PEG 600/Clay Nanocomposites

This study explored the crystallization and thermal properties of copolymers of polylactic acid–polyethylene glycol (Mn: 600) (PLLA–PEG 600 copolymer) nanocomposites with added montmorillonite (clay). The d-spacing of the hydrophilic montmorillonite was increased by using a quaternary ammonium salt. The salt was used to modify montmorillonite via ion exchange. The modified montmorillonite was then evenly dispersed in the matrix of the PLLA–PEG 600 copolymer to synthesize the nanoscale polymer via solution casting method. Thermogravimetric analysis and differential scanning calorimetry were used to measure the thermal properties of the PLLA–PEG 600 copolymers with various proportions of added clay. Wide-angle X-ray diffraction was used to identify the crystal structure and lattice displacements of PLLA–PEG 600 copolymer and the copolymer with added clay. Using polarized optical microscopy and transmission electron microscopy, the crystal growth and size of PLLA–PEG 600 copolymer with various proportions of added clay, as well as the dispersion of the clay, were observed. Adding clay to PLLA–PEG 600 copolymer improved its thermal properties and crystallinity without changing its original crystal structure.

Curing kinetic, thermal and adhesive properties of epoxy resin cured with cashew nut shell liquid

The curing kinetic, thermal and adhesive properties of epoxy resin cured with cashew nut shell liquid (CNSL) were investigated. The CNSL was used as a curing agent for epoxy resin. The epoxy resin cured with 10, 20 30, 40 and 50wt% of CNSL showed two-stages curing process between 165–170°C and 230–235°C. The solvent extraction experiment indicated that the CNSL content should not exceed 40wt% to avoid the presence of unreacted CNSL. The apparent activation energy (Ea) of 60/40 epoxy resin/CNSL copolymer was obtained from Friedman’s model-free method for both stages of curing process. The kinetic model and kinetic parameters were determined by Málek’s method and the reaction processes was simulated favorably by Sestak–Berggren (SB (m, n)) model. In addition, silica powder was used to improve the adhesion and thermal properties of copolymer. The epoxy resin/CNSL copolymer with 0.5wt% silica showed a substantial increase in the lap shear strength and thermal stability tended to increase with increasing silica content. The epoxy resin/CNSL composite showed a great potential for use as a high performance adhesive with good thermal stability.

Dynamic mechanical and thermal properties of copolymer from o-allylphenol and 4,4′-diaminodiphenyl methane-based benzoxazine and bisphenol-A type novolac epoxy resin

Benzoxazine/epoxy copolymers were prepared by solution blending bis(4-(8-allyl-2H-benzo[e][1,3]oxazin-3(4H)-yl)phenyl)methane (oAP-ddm) with bisphenol-A type novolac epoxy resin (bis-ANER), followed by thermally polymerization of the blend. The copolymerization behavior of oAP-ddm/bis-ANER was investigated by Fourier transform infrared spectroscopy and differential scanning calorimetry (DSC). With the increasing of bis-ANER fraction, the exothermic peak in DSC curve changes from one to two overlapped peaks, and the second peak shifts to higher temperatures. Dynamic mechanical analysis results show that a single peak appears in each tan δ curve of the oAP-ddm/bis-ANER copolymers. With the bis-ANER content increasing, the storage modulus and the peak temperature of tan δ peak increase, whereas the tan δ peak height decreases. Thermogravimetric analysis results indicate that the onset temperatures of mass loss and the char yields at 800 °C of the oAP-ddm/bis-ANER copolymers decrease with the increase of bis-ANER content.

Synthesis and structure control of l‐lactic acid–glycolic acid copolymer by homo‐copolymerization

ABSTRACTA two‐step direct melt copolymerization process of l‐lactic acid (L‐LA)/glycolic acid (GA) was developed: poly(l‐lactic acid) (PLLA) and poly(glycolic acid) (PGA) with different molecular weight was first synthesized respectively by binary catalyst (tin chloride/p‐toluenesulfonic or tin chloride); and then poly(l‐lactic‐co‐glycolic acid) (b‐PLGA) was produced by melt polymerization of the as‐prepared PLLA and PGA, wherein the composition and chain structure of b‐PLGA copolymers could be controlled by the molecular weight of PLLA. The chain structure and thermal properties of copolymers were studied by Wide‐angle X‐ray diffraction, nuclear magnetic resonance, differential scanning calorimetry, and thermogravimetric analysis. In comparison with the random PLGA (r‐PLGA) synthesized by one‐step direct melt polymerization, the average l‐lactic blocks length (LLA) in b‐PLGA was longer while the average glycolic blocks length (LGA) in b‐PLGA was shorter which further resulted in the improved crystallinity and thermostability. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41566.