Comonomer Composition Research Articles

Enhanced Flocculation of Oil Sands Mature Fine Tailings Using Hydrophobically Modified Polyacrylamide Copolymers.

Hydrophobically modified acrylamide copolymers dewater oil sands tailings more effectively than anionic polyacrylamide, but the root causes for this enhanced performance have not been investigated systematically. Polyacrylamide‐poly(ethylene oxide methyl ether methacrylate) copolymers with different comonomer compositions, hydrophobic chain lengths, and molecular weights to map out these effects systematically are synthetized. Through a statistical design of experiments, it is found out that all three variables above significantly affected flocculation performance and that certain combinations achieve optimal results. The effect of centrifugation on the flocculation and dewatering performance of these polymers is also investigated.

Guar Gum-Grafted Terpolymer Hydrogels for Ligand-Selective Individual and Synergistic Adsorption: Effect of Comonomer Composition.

Grafting of guar gum (GG) and in situ strategic attachment of acrylamidosodiumpropanoate (ASP) via solution polymerization of acrylamide (AM) and sodium acrylate (SA) resulted in the synthesis of a sustainable GG-g-(AM-co-SA-co-ASP)/GGAMSAASP interpenetrating polymer network (IPN)-based smart superadsorbent with excellent physicochemical properties and reusability, through systematic optimization by response surface methodology (RSM) for removal of methyl violet (MV) and/or Hg(II). The relative effects of SA/AM ratios, in situ allocation of ASP, grafting of GG into the AMSAASP terpolymer, ligand-selective superadsorption mechanism, and relative microstructural changes in individually/synergistically-adsorbed MV–/Hg(II)–/Hg(II)–MV–GGAMSAASPs were determined by extensive analyses using Fourier transform infrared (FTIR), proton nuclear magnetic resonance, ultraviolet–visible (UV–vis), and O 1s-/N 1s-/C 1s-/Hg 4f7/2,5/2-X-ray photoelectron spectroscopies, thermogravimetric analysis, differential scanning calorimetry, X-ray diffraction, field emission scanning electron microscopy, and energy-dispersive spectroscopy and were supported by % gel content, pHPZC, and % graft ratio. The ionic/covalent-bonding, monodentate, bidentate bridging, and bidentate chelating coordination between GGAMSAASPs and Hg(II), and MV+–Hg(II) bonding were rationalized by FTIR, UV–vis, fitment of kinetics data to the pseudo-second-order model, and thermodynamic parameters. The maximum adsorption capacities of 49.12 and 53.28 mg g–1 were determined for Hg(II) and MV, respectively, under optimized conditions.

Selective synthesis of highly soluble cyclic olefin copolymers with pendant vinyl groups using 1,5-hexadiene as a comonomer

Copolymerization of norbornene (NB) and 1,5-hexadiene (HD) was performed using a fluorenylamido-ligated titanium catalyst which conducts copolymerization of NB and 1-alkene. The obtained copolymers possessed pendant vinyl groups, of which content was varied from 0 to 9.4% by the initial feed ratio of the monomers. The copolymers were soluble in various solvents even at high conversion (>85%), showing that the crosslinking of pendant vinyl groups was negligible. The glass transition temperature of the copolymer was changed from 79 °C to over 300 °C, depending on the comonomer composition. Post-functionalization of the pendant vinyl groups with 3,3,4,4,5,5,6,6,6-nonafluoro-1-hexene via ruthenium-catalyzed metathesis reaction was also performed and fluoroalkyl-functionalized cyclic olefin copolymer was successfully obtained. The fluorinated copolymer film showed higher contact angle than the unfunctionalized copolymer.

Swelling behavior of poly (N-hydroxymethylacrylamide-co-acrylic acid) hydrogels and release of potassium nitrate as fertilizer

Abstract Poly (N-hydroxymethylacrylamide-co-acrylic acid) [P(NHMA-AAx)] hydrogels were prepared by free-radical polymerization in aqueous solution at 56°C, using N,N′-methylenebisacrylamide as the cross-linking agent. The synthesized hydrogels were subsequently investigated by a series of characterization techniques including Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis and differential scanning calorimetry analysis. The effects of comonomer composition in the feed, pH, temperature and ionic strength on the swelling behavior were studied. Results indicated that the swelling capabilities of P(NHMA-AAx) hydrogels decreased with the increase in N-hydroxymethylacrylamide (NHMA) content in the polymeric matrix and ionic strength of the medium. Additionally, the hydrogels showed both temperature and pH responses. The dynamic swelling behaviors of hydrogels at different pH values followed a non-Fickian type. The P(NHMA-AAx) hydrogels were also loaded with potassium nitrate (KNO3) as a model agrochemical, and the release kinetics of fertilizer from the hydrogels was studied as a function of KNO3 and NHMA concentrations. Moreover, various kinetic parameters, such as release exponents and diffusion coefficients, were calculated.

Ionic Conductivity and Assembled Structures of Imidazolium Salt-Based Block Copolymers with Thermoresponsive Segments.

Ionic liquid-based block copolymers composed of ionic (solubility tunable)–nonionic (water-soluble and thermoresponsive) segments were synthesized to explore the relationship between ionic conductivity and assembled structures. Three block copolymers, comprising poly(N-vinylimidazolium bromide) (poly(NVI-Br)) as a hydrophilic poly(ionic liquid) segment and thermoresponsive poly(N-isopropylacrylamide) (poly(NIPAM)), having different compositions, were initially prepared by RAFT polymerization. The anion-exchange reaction of the poly(NVI-Br) in the block copolymers with lithium bis(trifluoromethanesulfonyl)imide (LiNTf2) proceeded selectively to afford amphiphilic block copolymers composed of hydrophobic poly(NVI-NTf2) and hydrophilic poly(NIPAM). Resulting poly(NVI-NTf2)-b-poly(NIPAM) exhibited ionic conductivities greater than 10−3 S/cm at 90 °C and 10−4 S/cm at 25 °C, which can be tuned by the comonomer composition and addition of a molten salt. Temperature-dependent ionic conductivity and assembled structures of these block copolymers were investigated, in terms of the comonomer composition, nature of counter anion and sample preparation procedure.

Monomer composition effects on thermal properties of transparent poly(methyl methacrylate-co-isobornyl methacrylate-co-cyclohexyl maleimide) terpolymers

Terpolymers based on methyl methacrylate (MMA), isobornyl methacrylate (IBOMA) and N-cyclohexyl maleimide (ChMI) were synthesized by conventional free-radical solution copolymerization. The mole fraction of all polymers was characterized by elemental analysis and 1H NMR spectroscopy. The thermal and thermomechanical properties of all polymer series having different comonomer compositions were investigated by DSC, TGA, DMTA and TMA. The results showed improved heat resistance characteristics, in which both the glass transition and decomposition temperatures of the terpolymers were heightened with increasing IBOMA and ChMI comonomer content, due to their bulky pendent group and rigid imide ring structure. Furthermore, the dynamic mechanical properties as well as dimensional stability of the terpolymers increased with a higher IBOMA and ChMI content without sacrificing a high transparency of pure PMMA.

Radical Copolymerization Kinetics of Bio-Renewable Butyrolactone Monomer in Aqueous Solution

The radical copolymerization kinetics of acrylamide (AM) and the water-soluble monomer sodium 4-hydroxy-4-methyl-2-methylene butanoate (SHMeMB), formed by saponification of the bio-sourced monomer γ-methyl-α-methylene-γ-butyrolactone (MeMBL), are investigated to explain the previously reported slow rates of reaction during synthesis of superabsorbent hydrogels. Limiting conversions were observed to decrease with increased temperature during SHMeMB homopolymerization, suggesting that polymerization rate is limited by depropagation. Comonomer composition drift also increased with temperature, with more AM incorporated into the copolymer due to SHMeMB depropagation. Using previous estimates for the SHMeMB propagation rate coefficient, the conversion profiles were used to estimate rate coefficients for depropagation and termination (kt). The estimate for kt,SHMeMB was found to be of the same order of magnitude as that recently reported for sodium methacrylate, with the averaged copolymerization termination rate coefficient dominated by the presence of SHMeMB in the system. In addition, it was found that depropagation still controlled the SHMeMB polymerization rate at elevated temperatures in the presence of added salt.

Modified hydrogels based on poly(2-hydroxyethyl methacrylate) (pHEMA) with higher surface wettability and mechanical properties

Soft contact lenses made with poly(2-hydroxyethyl methacrylate) (pHEMA) hydrogels modified with various comonomers such as N-vinyl pyrrolidone, methacrylic acid, glycidyl methacrylate, and glycerol monomethacrylate were prepared to investigate the effect of adding the comonomer on the water content, surface wettability, and tensile modulus. These polymers were synthesized by the free radical polymerization of 2-hydroxyethyl methacrylate (HEMA) with the comonomers in the presence of divinyl benzene used as the crosslinker and azobisisobutyronitrile as the initiator. The chemical structure and transmittance of the hydrogels were analyzed by FTIR and UV/Vis spectrophotometers. The surface wettability and tensile modulus were also studied by measuring the contact angle and tensile modulus with a universal testing machine (UTM). Regarding the properties of water in the hydrogels, the ratio between free to bound water was investigated using differential scanning calorimetry (DSC). As the concentration of crosslinker in the hydrogels increases, the tensile strength also increases, whereas the internal water content and contact angle decrease. The effect of the comonomer composition of the hydrogels was also investigated to optimize the various properties of these comonomers for soft contact lenses.

Novel stimuli-responsive hydrogels derived from morpholine: synthesis, characterization and absorption uptake of textile azo dye

A new cationic monomer methacrylamido-4-(2-aminoethyl)morpholine, (MAEM) derived from morpholine was synthesized in a single step and characterized by FTIR, 1H and 13C NMR analyses. Through free radical aqueous polymerization, novel copolymeric hydrogels have been prepared successfully using methacrylamido-4-(2-aminoethyl)morpholine and acrylamide (Aam) as monomers. Later on SEM, FTIR, elemental analysis and TG instruments were used to characterize the obtained poly(acrylamide-co-methacrylamido-4-(2-aminoethyl)morpholine), poly(Aam-c-MAEM), hydrogels. Poly(Aam-c-MAEM) hydrogels were tested for swelling, diffusion and uptake of reactive orange, RO, anionic dye. In this regard, various adsorption kinetics and isotherm models as well as operation parameters were systematically examined and discussed in detail in relation to adsorption uptake such as pH of media, comonomer composition, adsorbent dosage, temperature, initial dye concentration and contact time. The description of adsorption process of RO on hydrogels was consistent with the pseudo-second-order model followed by Elovich and pseudo-first-order. The best fitting adsorption model was selected on the basis of R 2, in the order of: Temkin > D-R > Langmuir > Freundlich isotherm. The results obtained in this study demonstrate that poly(Aam-c-MAEM) hydrogels provide an excellent advantage for application of this hydrogel system in the removal of anionic textile dyes from wastewater.

Preparation of biomass-based transparent pressure sensitive adhesives for optically clear adhesive and their adhesion performance

UV-cured transparent acrylic pressure sensitive adhesives (PSAs) composed of semi-interpenetrating networks were prepared using the menthyl acrylate (MnA) and tetrahydro-geraniol acrylate (TGA) synthesized from menthol and tetrahydro geraniol, respectively. This study investigated the adhesion performance and environmental reliability of the resulting acrylic PSAs by changing the mole ratio for MnA and TGA while fixing the mole ratio for 2-hydroxyehtyl acrylate (2-HEA) in the PSAs. Also, the optical properties of the acrylic PSAs for optically clear adhesive applications were examined by UV–Vis spectroscopy, color-difference meter, and haze meter. All acrylic PSAs exhibited high transparency (>92%) and stable weatherability under reliability testing (85/85 test), regardless of the various comonomer compositions. The resulting acrylic PSAs showed proper adhesion performance to be allowed to use as optically clear adhesive; 180° peel strength of 1.6–4.0 kgf/25mm, probe tack of 0.25–0.43 kgf, and shear holding power of 0.10–0.17mm.

Further Insight into the Mechanism of Poly(styrene-co-methyl methacrylate) Microsphere Formation.

Polymeric microspheres have been utilized in a broad range of applications ranging from chromatographic separation techniques to analysis of air flow over aerodynamic surfaces. The preparation of microspheres from many different polymer families has consequently been extensively studied using a variety of synthetic approaches. Although there are a variety of methods of synthesis for polymeric microspheres, free-radical initiated emulsion polymerization is one of the most common techniques. In this work, poly(styrene-co-methyl methacrylate) microspheres were synthesized via surfactant-free emulsion polymerization. The effect of co-monomer composition and addition time on particle size distribution, particle formation, and particle morphology were investigated. Particles were characterized using dynamic light scattering (DLS) and scanning electron microscopy (SEM) to gain further insight into particle size and size distributions. Reaction kinetics were analyzed alongside of characterization results. A particle formation mechanism for poly(styrene-co-methyl methacrylate) microspheres was proposed based on characterization results and known reaction kinetics.

Impact of surfactant on the pore and particle sizes of copolymer (2‐acrylamido‐2‐methylpropane sulfonic acid/acrylamide) nanohydrogels for controlled release of 5‐fluorouracil

Nanohydrogels were prepared from copolymerization of acrylamido‐2‐methylpropane sulfonic acid (AMPS) and acrylamide (AAm) in presence of sodium lauryl sulfate (SLS). The direct ionizing radiation of γ‐rays was used to initiate the copolymerization reaction. The different concentrations of SLS, variable irradiation doses, a fixed total monomer concentration, and comonomer composition were used. The features of nanohydrogel were characterized by Fourier transform infrared, thermal gravimetric analysis, and BET surface area analysis of porosity. The results confirmed the structure formation of copoly(AMPS/AAm) nanohydrogels. The SLS concentration affects clearly the pore characteristics and nanoparticle sizes. The nanoparticle and pore size distributions referred to that the pores and nanoparticle formed in wide range of nanoscale. The surface area and pore volume depended basically on the SLS concentration. The gel fraction of nanohydrogels ranged from (98 ± 2.3) to (100 ± 1.5)%. The nanohydrogels were used in in vitro release of 5‐fluorouracil (5‐FU) at different simulated fluids. The release profile showed a prolonged release of 5‐FU at two different simulated fluids of pHs of 1.2 for simulated gastric fluid and 7.4 for simulated intestinal fluid. The study demonstrated that copoly(AMPS/AAm) nanohydrogel may serve as a promising material for the sustained release of 5‐FU in stomach and colon media. POLYM. ENG. SCI., 58:94–102, 2018. © 2017 Society of Plastics Engineers

Tailoring Copolymer Properties by Gradual Changes in the Distribution of the Chains Composition Using Semicontinuous Emulsion Polymerization.

To design the properties of a copolymer using free radical polymerization, a semicontinuous process can be applied to vary the instantaneous copolymer composition along the conversion searching for a specific composition spectrum of copolymer chains, which can be termed as weight composition distribution (WCD) of copolymer chains. Here, the styrene-n-butyl acrylate (S/BA) system was polymerized by means of a semicontinuous emulsion process, varying the composition of the comonomer feed to obtain forced composition copolymers (FCCs). Five different feeding profiles were used, searching for a scheme to obtain chains rich in S (looking for considerable modulus), and chains rich in BA (looking for large deformation) as a technique to achieve synergy in copolymer properties; the mechanostatic and dynamic characterization discloses the correspondence between WCD and the bulk properties. 1H-nuclear magnetic resonance (1H-NMR) analysis enabled the determination of the cumulative copolymer composition characterization, required to estimate the WCD. The static test (stress-strain) and dynamic mechanical analysis (DMA) were performed following normed procedures. This is the first report that shows very diverse mechanostatic performances of copolymers obtained using the same chemical system and global comonomer composition, forming a comprehensive failure envelope, even though the tests were carried out at the same temperature and cross head speed. The principles for synergic performance can be applied to controlled radical copolymerization, designing the composition variation in individual molecules along the conversion.

Synthesis of Hydroxy-Functionalized Cyclic Olefin Copolymer and Its Block Copolymers with Semicrystalline Polyolefin Segments.

Synthesis of hydroxy-functionalized cyclic olefin copolymer (COC) is achieved with remarkably high activity (up to 5.96 × 107 g-polymer mol-Ti-1 h-1 ) and controlled hydroxy group in a wide range (≈17.1 mol%) by using ansa-dimethylsilylene (fluorenyl)(amido)titanium complex. The catalyst also promotes living/controlled copolymerization to afford novel diblock copolymers consisting of hydroxy-functionalized COC and semicrystalline polyolefin sequence such as polyethylene and syndiotactic polypropylene, where the glass transition temperature of the norbornene/10-undecen-1-ol segment and each block length are controlled by comonomer composition and copolymerization time, respectively.

Rotational mobility of the radical probe in butadiene-nitrile rubbers

The difference in co-monomer composition of the disordered phase of butadiene-nitrile rubbers of BNKS and SKN grades is determined by EPR spectroscopy. The degree of aggregation of fragments consisting of alternating units and looseness of the disordered rubber phase in the case of BNKSs are shown to be higher than those of SKNs. The rotational mobility of the radical-probe indicates the lowering of the straight chain flexibility to be more pronounced in the case of BNKS rubbers. This phenomenon is due to the more large-size nanostructures if compared to the ones in SKNs.

Amphiphilic block-random copolymer surfactants with tunable hydrophilic/hydrophobic balance for preparation of non-aqueous dispersions by an emulsion solvent evaporation method

The structural effects of amphiphilic block-random copolymers composed of stearyl methacrylate (SMA) and diethanolamine-modified glycidyl methacrylate (DEAGMA), poly(SMA)-b-poly(DEAGMA-r-SMA)s on their surfactant efficacy for a non-aqueous emulsion solvent evaporation method were investigated. Three series of block-random copolymers (i) with different amounts of DEAGMA in the poly(DEAGMA-r-SMA) segment and (ii, iii) with different chain lengths of each segment were synthesized by reversible addition-fragmentation chain transfer polymerization. The surfactant efficacies of these copolymers were investigated in terms of the interfacial tension and modulus, size, and stability of the emulsion and dispersion. Suitable comonomer composition and chain lengths of both segments produced stable emulsions and dispersions with small particle sizes (<200nm).

Synthesis and properties of novel biodegradable poly(butylene succinate-co-decamethylene succinate) copolyesters from renewable resources

Through a two-step melt polycondensation method, three novel poly(butylene succinate-co-decamethylene succinate) (PBDS) copolyesters containing low decamethylene succinate (DS) comonomer compositions from 12 to 33 mol% and its homopolymer poly(butylene succinate) (PBS) were successfully synthesized. The molecular weight, composition, basic thermal behaviors, crystal structure, and mechanical properties of PBDS with different DS compositions and PBS were studied. PBDS and PBS had high thermal stability and the same crystal structure, but the PBDS copolymers showed smaller crystallinity than PBS. The glass transition temperature, melting point temperature, nonisothermal melt crystallization peak temperature, and equilibrium melting point temperature of PBDS were smaller than those of PBS and obviously decreased with the increase of the DS composition. The composition dependence of melting point temperature for the PBDS copolymers was well described by the Flory equation. With increasing the DS composition, the elongation rate at break of PBDS increased significantly, while the yield stress, Young modulus, and tensile strength decreased gradually.

Polyethylene comonomer characterization by using FTIR and a multivariate classification technique

Many polyethylene (PE) films used in various packaging applications are based on multi-layer systems and are fabricated by using the coextrusion techniques that can combine different raw materials. The identification of the comonomer type (octene – C8, hexene – C6 and butene – C4) in films, where two or more different linear low density polyethylene (LLDPE) resins are present, is becoming a frequent request. This report presents a novel approach where multivariate classification techniques are used in combination with FTIR for the identification of the comonomer type in coextruded films. A set of different LLDPE coextruded samples have been measured by FTIR, and the resulting spectra processed by Principal Component Analysis (PCA). By projecting the samples to the scores plots a difference is observed as a function of comonomer composition. This approach, compared with others is much faster, as just the time of measuring a film by direct infrared analysis is required.

Cationic photopolymerization of 3‐benzyloxymethyl‐3‐ethyl‐oxetane

AbstractThe cationic photopolymerization of 3‐benzyloxymethyl‐3‐ethyl‐oxetane (MOX104) initiated by triphenylsulfonium hexafluoroantimonate under UV light was conducted. The kinetics were investigated by real‐time Fourier transform IR spectroscopy and the mechanical and thermal properties of poly(MOX104) were examined by dynamic mechanical analysis and TGA. To adjust the properties of the polymer, different initiator concentrations and comonomer composition were applied. The results showed that the conversion of MOX104 was improved significantly from 17% to almost 90% by adding a certain amount of 3,4‐epoxycyclohexane carboxylate or diglycidyl ether of bisphenol A epoxy resin, while not much effect was observed by adding 1,4‐butanediol diglycidyl ether. Moreover, the glass transition temperature, decomposition temperature and Young's modulus of poly(MOX104) were improved by adding different amounts of diglycidyl ether of bisphenol A epoxy resin. © 2016 Society of Chemical Industry

The Combined Influence of Monomer Concentration and Ionization on Acrylamide/Acrylic Acid Composition in Aqueous Solution Radical Batch Copolymerization

An in situ NMR technique is used to measure the relative monomer consumption rates of acrylamide (AM) and acrylic acid (AA) over a broad range of initial comonomer compositions, initial monomer concentrations (5–40 wt % in aqueous solution), and the complete range of AA ionization. The composition drift with conversion was found not only to be a strong function of AA ionization but also to vary systematically with monomer concentration, with the latter influence increasing at increased degrees of ionization. The coupled effect is captured by expressions developed to represent the monomer reactivity ratios as a function of these two major variables. The proposed correlation, easily implemented into any modeling framework, is based on experimentally measured composition over a much broader range of conditions than examined in previous studies and accurately captures the effect of monomer concentration at low and high degrees of ionization.