Synthesis of defined polyhedral oligosilsesquioxane‐containing diblock and triblock methacrylate copolymers by atom transfer radical polymerization

Defined diblock and triblock copolymers composed of methyl methacrylate‐co‐glycidyl methacrylate block and 3‐{3,5,7,9,11,13,15‐hepta(2‐methylpropyl)‐pentacyclo[9.5.1.1^3,9.1^5,15.1^7,13]‐octasiloxan‐1‐yl}propyl methacrylate block(s), i.e., P(MMA‐co‐GMA)‐b‐PiBuPOSSMA and PiBuPOSSMA‐b‐P(MMA‐co‐GMA)‐b‐PiBuPOSSMA, were synthesized by atom transfer radical polymerization (ATRP). First, monofunctional and bifunctional P(MMA‐co‐GMA) copolymers were synthesized by ATRP. Subsequently, these copolymers were successfully used as macroinitiators for ATRP of POSS‐containing methacrylate monomer. The process showed high initiation efficiency of macroinitiators and led to products with low dispersity. The synthesized block copolymers were characterized by size exclusion chromatography, ¹H‐NMR spectroscopy and their glass transition temperatures were determined by differential scanning calorimetry. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Effect of including a hydrophobic comonomer on the rheology of an acrylamide-acrylic acid based copolymer

Synthesis and design of polymer systems based on acrylamide for enhanced oil recovery (EOR) is essential for reservoirs with high salinity and high temperature conditions. The use of associative monomers or the modification of the polymers with hydrophobic functional groups represents a promising alternative that extends the use of chemical EOR. In this study, terpolymers based on acrylamide, acrylic acid and butyl methacrylate were synthesized and the rheological properties of aqueous solutions of the obtained polymers at different pH values, and salt concentrations were evaluated. The results show that at alkaline conditions the viscosity of aqueous solutions of a polymer synthesized with 68.6 wt% of acrylamide, 22.9 wt% of acrylic acid and 8.6 wt% of butyl methacrylate increases by a factor of more than 1,000 at a 3 wt% concentration. Also, all polymers with the hydrophobic modification showed higher viscosity in saline solutions compared to their acrylamide-acrylic acid analogue.     

Synthesis and photopolymerization of acrylic acrylate copolymers

Acrylate‐functionalized copolymers were synthesized by the modification of poly(butyl acrylate‐co‐glycidyl methacrylate) (BA/GMA) and poly(butyl acrylate‐co‐methyl methacrylate‐co‐glycidyl methacrylate). ¹³C‐NMR analyses showed that no glycidyl methacrylate block longer than three monomer units was formed in the BA/GMA copolymer if the glycidyl methacrylate concentration was kept below 20 mol %. We chemically modified the copolymers by reacting the epoxy group with acrylic acid to yield polymers with various glass‐transition temperatures and functionalities. We studied the crosslinking reactions of these copolymers by differential scanning calorimetry to point out the effect of chain functionality on double‐bond reactivity. Films formed from acrylic acrylate copolymer precursors were finally cured under ultraviolet radiation. Network heterogeneities such as pendant chains and highly crosslinked microgel‐like regions greatly influenced the network structure and, therefore, its viscoelastic properties. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 753–763, 2002     

Synthesis of electroactive tetraaniline-based acrylic polyol by atom transfer radical polymerization for anticorrosive coating application

In this work, block copolymers of butyl acrylate and glycidyl methacrylate (GMA) having molecular weights 10,000 Da were synthesized with varied GMA block lengths by 10%, 20%, and 30% using atom transfer radical polymerization. The synthesized copolymers were further reacted with tetraaniline to formulate conductive polyol and further characterized by mass spectroscopy, UV–visible spectroscopy, ¹HNMR, and FTIR. The block copolymers formed were evaluated by gel permeation chromatography, Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry, and nuclear magnetic resonance (NMR) techniques for structural elucidation. These polyols were formed with 10, 20, and 30 wt% with isocyanate (HDI N-3300) to form a polyurethane. The effect of concentration of conducting polyol on anticorrosive coating performance properties, namely mechanical and optical properties, was further studied. The anticorrosive performance was evaluated by salt spray test and electrochemical impedance spectroscopy.     

Synthesis and characterization of high molecular weight side chain liquid crystalline/photoactive polymers

Various liquid crystalline and photoactive azobenzene monomers were synthesized and attached to copoly(methyl methacrylate‐glycidyl methacrylate) [copoly (MMA‐GMA)] to get high molecular weight side chain liquid crystalline (LC)/photoactive copolymers. Further, spacers are generated in situ and reactive groups are obtained after the modification. All monomers and polymers were thoroughly characterized by FTIR, ¹H and ¹³C NMR, UV‐VIS spectrophotometry, gel permeation chromatography, thermogravimetric analysis, differential scanning calorimetry, and polarized optical microscopy. All side chain LC polymers showed higher thermal stability than that of copoly(MMA‐GMA). Three LC and one azo monomer exhibited characteristic nematic mesophase where as one LC monomer has shown nematic and sanded smectic‐A texture. The rate of trans‐cis isomerization of polymer was lower than that of the monomer and both monomers and polymers showed slow back isomerization. Present approach offers convenient way to synthesize high/desired molecular weight photoactive LC polymers. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Optimization of comb‐shaped polycarboxylate cement dispersants to achieve fast‐flowing mortar and concrete

Concretes and mortars possessing a low water‐to‐cement (w/c) ratio (<0.40) liquefied with comb‐shaped polycarboxylate (PCE) copolymers commonly exhibit a sticky, honey‐like consistency, and slow flow behavior. The stickiness is owed to high plastic viscosity of the suspension. In this study, different PCE comb polymers based on methacrylate ester, allyl, vinyl, and isoprenyl ether macromonomers were synthesized and analyzed. It was found that their hydrophilic–lipophilic balance (HLB) value, i.e., the balance between the hydrophilic and lipophilic parts in these PCE molecules determines their effect on the plastic viscosity of a concrete. PCE copolymers mainly composed of hydrophilic parts, i.e., such possessing high HLB values, impart low plastic viscosity. Allyl ether—maleic acid based PCEs exhibit especially high HLB values and thus impart low plastic viscosity. Higher viscosities were recorded for isoprenylether PCEs, while methacrylate‐ester and vinyl ether PCEs possess particularly low HLB values and hence produce a pronounced sticky concrete. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42529.     

Functional copolymers of p‐cumyl phenyl methacrylate and glycidyl methacrylate: Synthesis,characterization, and reactivity ratios

Free‐radical polymerization of p‐cumyl phenyl methacrylate (CPMA) was performed in benzene using bezoyl peroxide as an initiator at 80°C. The effect of time on the molecular weight was studied. Functional copolymers of CPMA and glycidyl methacrylate (GMA) with different feed ratios were synthesized by free‐radical polymerization in methyl ethyl ketone at 70°C, and they were characterized by FTIR and ¹H‐NMR spectroscopy. The molecular weights and polydispersity indexes of the polymers and copolymers were determined by gel permeation chromatography. The copolymer composition was determined by ¹H‐NMR. The glass‐transition temperature of the polymer and the copolymers was determined by differential scanning calorimetry. The reactivity ratios of the monomers were determined by the Fineman–Ross and Kelen–Tudos methods. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 336–347, 2005     

Methacrylate-based block ionomers I: Synthesis of block ionomers derived from t-butyl methacrylate and alkyl methacrylates

Diblock and triblock copolymers of t-butyl methacrylate (tBMA) with 2-ethylhexyl methacrylate (EHMA) and n-hexyl methacrylate were prepared via alkyl lithium initiation and sequential addition techniques in THF at ?78°C. The tBMA blocks were quantiatively and selectively hydrolyzed to afford poly(methacrylic acid) (PMAA) blocks which were then neutralized with alkali metal bases to form block ionomers. The unhydrolyzed copolymers had a phase mixed morphology as evidenced by thermal analysis while the hydrolyzed and neutralized polymers were multiphase materials. The carboxylic acid and ioncontaning triblock copolymers formed gels in nonpolar solvents which could be disrupted by the addition of polar additives. Certain carboxylic acid and ioncontaining EHMA/tBMA diblock copolymers also showed this behavior. The triblock ionomers did not show thermoplastic flow prior to degradation, except at the lowest ionic content studied (2%).     

Reactive mixing of PET and PET/PP blends with glycidyl methacrylate–modified styrene‐b‐(ethylene‐co‐olefin) block copolymers

Styrene‐b‐(ethylene‐co‐butylene)‐b‐styrene (SEBS) and styrene‐b‐(ethylene‐co‐propylene) (SEP, SEPSEP) block copolymers with different styrene contents and different numbers of blocks in the copolymer chain were functionalized by melt radical grafting with glycidyl methacrylate (GMA) and employed as compatibilizers for PET‐based blends. Binary blends of PET with both functionalized (SEBS‐g‐GMA, SEP‐g‐GMA, SEPSEP‐g‐GMA) and neat (SEBS, SEP, SEPSEP) copolymers (75 : 25 w/w) and ternary blends of PET and PP (75 : 25 w/w) with various amounts (2.5–10 phr) of both modified and unmodified copolymers were prepared in an internal mixer, and their properties were evaluated by SEM, DSC, melt viscosimetry, and tensile and impact tests. The roles of the chemical structure, grafting degree, and concentration of the various copolymers on blend compatibilization was investigated. The blends with the grafted copolymers showed a neat improvement of phase dispersion and interfacial adhesion compared to the blends with nonfunctionalized copolymers. The addition of grafted copolymers resulted in a marked increase in melt viscosity, which was accounted for by the occurrence of chemical reactions between the epoxide groups of GMA and the carboxyl/hydroxyl end groups of PET during melt mixing. Blends with SEPSEP‐g‐GMA and SEBS‐g‐GMA, at concentrations of 5–10 phr, showed a higher compatibilizing effect with enhanced elongation at break and impact resistance. The effectiveness of GMA‐functionalized SEBS was then compared to that of maleic anhydride–grafted SEBS. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 2201–2211, 2005     

Study of oil soluble polymers as drag reducers

This investigation was undertaken to find the most effective material which would reduce the friction coefficient in turbulent flow when added in small quantities to oil pipelines. For this purpose, a series of oil-soluble polymers, namely homopolymers and copolymers of alkyl methacrylates, alkyl acrylates, and alkyl styrenes were synthesized. Emulsion polymerization techniques were used. Commercially available alkyl methacrylate and alkyl acrylate monomers were used in the synthesis. Monomeric alkyl styrenes were synthesized and structures established prior to polymerization. Intrinsic viscosities were measured and viscosity average molecular weights were calculated for several of the homopolymers synthesized in this study. Reduction of factional drag and resistance to shear degradation were measured by pumping a solution of the polymer in a hydrocarbon solvent through a pipe and recording the pressure drop across the pipe. Drag-reducing properties of several of the polymers were correlated in terms of their viscosity average molecular weights. Drag reduction of poly (isodecyl methacrylate) was studied in various hydrocarbon solvents. Drag-reducing behavior of polymers prepared in this study exhibited a strong dependence on molecular weight; increasing the molecular weight increased the drag reduction for a given polymer concentration and pipe size. Several of these polymers were found to be superior to commercially available polyisobutylene as drag reducers, especially in terms of shear stability.     

Amphiphilic diblock and ABC triblock methacrylate copolymers: synthesis and aqueous solution characterization

Three isomeric, linear, equimolar, amphiphilic ABC triblock copolymers comprising methyl methacrylate (MMA, nonionic hydrophobic), 2-(dimethylamino)ethyl methacrylate, (DMAEMA, ionizable hydrophilic) and hexa(ethylene glycol) methacrylate (HEGMA, nonionic hydrophilic) units (10 units in each block) were synthesized by group transfer polymerization (GTP). These were the three block sequence isomers, ABC, ACB and BAC. The corresponding random terpolymer was also prepared. The molecular weights and compositions of all the polymers were characterized by GPC and ¹H NMR. Measurements of the hydrodynamic diameters and cloud points of the copolymers in aqueous solution suggest that the various distributions of monomer units in the four terpolymers (the three triblocks and the random) result in different supramolecular structures with different colloidal stabilities.     

Viscosity study of salt tolerant polymers

The rheological characteristics of copolymers of acrylamide (AM) with sodium salt of 2‐acrylamido‐2‐methylpropane sulfonic acid (PAMS), and of hydrolyzed polyacrylamide (HPAM) have been studied in both NaCl solutions and synthetic seawater. PAMS may possible have high salt tolerance and thereby find use in enhanced oil recovery processes for high salinity reservoirs. The viscosity and solubility effect of the PAMS copolymers have been systematically studied with variations in sulfonation degree and molecular weight. Emphasis has been studies as a function of shear rate, polymer concentration, NaCl and divalent ions concentration in aqueous phase. Shear rate dependence of PAMS varies with sulfonation degree, and PAMS with higher sulfonation degree is found to be less shear rate dependent. PAMS with high sulfonation degree are more salt tolerant also compared to HPAM. Also the effect of divalent ions on viscosity of PAMS is lower compared to HPAM. Two parameters will increase the solubility effect of the PAMS copolymers in mix brine, one is sulfonation degree and the other is in the presence of NaCl. Both parameters have a direct effect on the solubility of PAMS copolymer in mixed brine. In all cases the PAMS copolymers are more salt tolerant than HPAM. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Thermotropic liquid‐crystalline polymers: Synthesis,characterization, and properties of poly(azomethine esters)

A series of poly(azomethine ester) copolymers were synthesized by the solution polycondensation method with different diamines. The synthesized polymers were characterized by Fourier transform infrared spectroscopy, thermogravimetric analysis, differential scanning calorimetry (DSC), hot‐stage polarized microscopy, wide‐angle X‐ray diffraction, and solution viscosity. All polymers showed good thermal stability. The thermotropic liquid‐crystalline properties were examined by DSC and by microscopic observations. Except for one, all of the polymers showed nematic liquid‐crystalline behavior. The effects of temperature on crystallinity and the substituent on solubility, thermal stability, melting temperature, and viscosity were also studied. The voluminosity and shape factor were also computed from the viscosity data. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 153–160, 2003     

Synthesis of poly(dodecyl methacrylate)s and their drag‐reducing properties

Dodecyl methacrylate was synthesized as the intermediate monomer for the preparation of poly(dodecyl methacrylate)s, which were synthesized with emulsion polymerization techniques. The intrinsic viscosities were measured, and the viscosity‐average molecular weights were calculated. Polymers of dodecyl methacrylate with ultrahigh molecular weights (viscosity‐average molecular weight > 10⁷) were synthesized through orthogonal experiments. The drag‐reduction properties of these polymers were studied in kerosene. The drag‐reducing behavior of these polymers exhibited a strong dependence on the molecular weight and Reynolds number, and these polymers could be used as effective oil‐soluble drag reducers and had good shear stabilities. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 1622–1626, 2003     

Synthesis, structure and properties of hydrophobically associating polymers

Hydrophobically modified water-soluble polymers have recently become the subject of extensive research because of their use as aqueous viscosity modifiers in oil recovery and latex paint systems. In this study, poly(acrylamide) samples modified with small amounts of a hydrophobic monomer (ethylphenylacrylamide) have been prepared by free radical copolymerization using an aqueous micellar process in which the use of a surfactant ensures the solubilization of the hydrophobe. The copolymers exhibit improved thickening properties with respect to homopoly(acrylamide) analogs due to intennolecular hydrophobic associations. The aqueous solution-copolymer properties strongly depend on the amount of surfactant used in the synthesis. The differences observed between the samples are directly related to the copolymer microstructure, that is to a more or less block distribution of the hydrophobic units. The interactions in aqueous solution of a surfactant (sodium dodecylsulfate (SDS)) with these copolymers have been examined. A strong increase in viscosity is observed upon the addition of SDS below its critical micelle concentration, owing to the formation of mixed micelles of SDS and hydrophobic monomers. The complex rheological behavior observed is explained in terms of the balance between inter and intrachain liaisons. The effects of hydrolysis on the hydrophobic interactions are also discussed.     

Solution and interfacial behavior of hydrophobically modified water-soluble block copolymers of acrylamide and N-phenethylacrylamide

Hydrophobically modified water-soluble block copolymers were prepared by aqueous micellar copolymerization of acrylamide and small amounts (2 and 3 mol %) of a hydrophobe (N-phenethylacrylamide) that is characterized by a long spacer that places the aromatic ring far away from the backbone, with the objective of investigating the copolymers' rheological behavior and surface and interfacial activities under various conditions such as polymer concentration, shear rate, temperature, and salinity. As expected, the block copolymers exhibit improved thickening properties attributed to intermolecular hydrophobic associations as the solution viscosity of the copolymers increases sharply with increasing polymer concentration. Additional evidence for intermolecular association is provided by the effect of NaCl, the presence of which substantially enhances the viscosity. An almost shear rate–independent viscosity (Newtonian plateau) is also exhibited at high shear rate and a typical non-Newtonian shear thinning behavior appears at low shear rates and high temperatures. Furthermore, the block copolymers exhibit high air–liquid surface and liquid–liquid interfacial activities as the surface and interfacial tensions decrease with increasing polymer concentration, indicating strong adsorption of the copolymer at the interface. The surface and interfacial tensions exhibited by the copolymers were found to be relatively insensitive to the concentration of salt (NaCl). © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 467–476, 2001     

pH- and temperature-responsive amphiphilic diblock copolymers of 4-vinylpyridine and oligoethyleneglycol methacrylate synthesized by RAFT polymerization

Diblock copolymers of 4-vinylpyridine (4VP) and oligoethyleneglycol methyl ether methacrylate (OEGMA) were synthesized for the first time using RAFT polymerization technique as potential drug delivery systems. Effects of the number of ethylene glycol units in OEGMA, chain length of hydrophobic P4VP block, pH, concentration and temperature on the solution behavior of the copolymers were investigated comprehensively. Copolymer chains formed micelles at pH values higher than 5 whereas unimeric polymers were observed to exist below pH 5, owing to the repulsion between positively charged P4VP blocks. The size of the micelles was dependent on the relative length of blocks, P4VP and POEGMA. Thermo-responsive properties of copolymers were investigated depending on the pH and length of P4VP block. The increase in the length of P4VP block decreased the LCST substantially at pH 7. At pH 3, LCST of copolymers shifted to higher temperatures due to the increased interaction of copolymers with water through positively charged P4VP block.     

Preparations and oil absorptivities of poly(stearyl methacrylate-co-cinnamoyloxyethyl methacrylate) and PET nonwoven fiber photocrosslinked with it

Cinnamoyloxyethyl methacrylate (CEMA) was synthesized by the reaction of cinnamoyl chloride (CMC) and 2-hydroxyethyl methacrylate (HEMA). Its copolymers with stearyl methacrylate (SMA) were synthesized using benzoyl peroxide (BPO) as an initiator. The synthesized copolymers, poly(SMA-co-CEMA)s (PSCMAs), were photocrosslinked by UV light irradiation. The structures of the products were confirmed by IR and NMR spectroscopies. The thermal properties of the synthesized polymers were determined by DSC. The crystalline melting temperature of crosslinked PSCMA was decreased with increasing CEMA content in the feed. The oil absorptivities of the synthesized polymers were evaluated by the ASTM method (F726-81). The highest oil absorptivity of crosslinked PSCMA on poly(ethylene terephthalate) (PET) nonwoven fiber (NWF) was 610% in 10% crude oil diluted with toluene when the mol percentage of CEMA to SMA in the feed was 7.5. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 2349–2357, 1999     

The performance of polymer solutions in enhanced oil recovery: studies on their rheological,interfacial, and porous media behaviors

Four polymeric solutions based on xanthan, high and low molecular weight sulfonated polyacrylamides, and hydrolyzed polyacrylamide were prepared in aqueous solutions and their behaviors in enhanced oil recovery applications were investigated. The effect of thermal aging on polymer solutions was evaluated through rheological measurement. Pendant drop method was also used for measuring the interfacial tension (IFT) between crude oil and brine containing different polymer solutions. Moreover, the zeta potential of the oil reservoir particles treated with oil and polymer was determined by electrophoresis method in a nano-zeta meter instrument. In addition, sand pack and core flooding setup were used for evaluating the effectiveness of the polymer solutions in porous media. Polymer solutions displayed non-Newtonian behavior in almost the whole range of the shear rate applied; a shear thinning behavior was seen. Furthermore, the aging of polymers in formation water decreased the shear viscosity of all the polymers. The oil/water IFT decreased by the addition of polymers to water. The effect of xanthan polymer on zeta potential value was greater than that of the three acrylamide-based polymers. According to sand pack tests, by increasing the polymer concentration, the incremental oil recovery initially increased up to a polymer concentration of 3,500 ppm and then started to fall. Recovery factor increased from 50 to 65 % using the polymer solution in core flooding experiments. By increasing the injection rate from 0.2 to 3 mL/min, the injected fluid had less time to sweep the pores and consequently the amount of recovered oil decreased.     

Thermal stability of polymers based on acrylamide and 2-acrylamido-2-methylpropane sulfonic acid in different temperature and salinity conditions

Partially hydrolyzed polyacrylamide (PHPA) is the most widely used polymer in enhanced oil recovery (EOR) applications. However, under conditions of high temperature and salinity, the PHPA molecules become hydrolyzed, causing a drastic reduction of the viscosity of the polymer solution due to the presence of negative charges, making the molecules more susceptible to interactions with cations. In this sense, in order to increase the stability of these polymers, an anionic monomer more resistant to cations such as 2-acrylamido-2-methylpropane sulfonic acid (AMPS) has been incorporated into the HPAM molecules. This work evaluated the thermal stability of a copolymer (acrylamide and AMPS - AN125) and a terpolymer (acrylamide, acrylate, and AMPS-FP5115) in the time course of 360 days. The tests were carried out in typical conditions of Brazilian offshore reservoirs, such as absence of oxygen, high temperature, and high salt concentration. The test method involved measurements of intrinsic viscosity in function of time and determination of the hydrolysis degree of the polymers by elemental analysis. The copolymer AN125 was more stable under the test conditions than the terpolymer FP 5115 due to the presence of a higher concentration of AMPS in the copolymer. The AMPS group was hydrolyzed to AA at a temperature of 100 °C, however, the increase in salt concentration delayed the onset of this degradation. The tests indicated that the presence of a higher AMPS content in the copolymer does not prevent the polymer from undergoing hydrolysis, but delays the polymer precipitation step in the solution.