Crosslinkable surfactants based on linoleic acid-functionalized block copolymers of ethylene oxide and ε-caprolactone for the preparation of stable PMMA latices

Amphiphilic diblock and triblock copolymers consisting of poly(ethylene oxide) (PEO) as (central) hydrophilic segment and poly(ε-caprolactone) (PCL) as hydrophobic segment(s) were prepared by ring opening polymerization. The length of the PEO segment was kept constant , whereas the length of the PCL block(s) was either 6 or 10 units for diblock copolymers and 3 or 5 units at each end for the triblock copolymers. These block copolymers were end-functionalized by esterification with linoleic acid (LA), which contains reactive double bonds. The autoxidative behavior of PEO₄₅-(CL₃-LA)₂ functionalized triblock copolymers was investigated by exposure of films to air at ambient conditions. Ninety percent of the double bonds had disappeared in 15 d and a crosslinked structure was obtained after 30 d. Critical micelle concentrations (CMC) of the crosslinkable surfactants were in the range of 0.08-0.19 mmol/l for the diblock copolymer and of 0.19-0.26 mmol/l for the triblock copolymer. The surface tension of aqueous surfactant solutions at the CMC (γ_CMC) (25 °C) varied from 47.1 to 51.4 mN/m for the diblock and from 45.6 to 48.1 mN/m for the triblock systems. For both systems CMC and γ_CMC increase with increasing HLB values. These surfactants were used in PMMA latex preparations. The latices of PMMA prepared with LA-functionalized diblock and triblock copolymers yielded narrow particle size distributions and particle sizes of 180 and 370 nm, respectively, whereas latices prepared with SDS had a particle size of 90 nm. After extraction of the latex particles with methanol, the amounts of the unextractable (either buried or copolymerized) LA-functionalized diblock and triblock copolymers found in extracted PMMA latex particles were 10 and 24% of the initial amount of surfactant added respectively. Control experiments with a stearic acid (SA) containing diblock copolymer showed that the amount of buried surfactant in PMMA latices was 6.5%. By comparing the overall latex characteristics and stability (shelf stability, freeze-thaw testing and addition of electrolyte solutions and ethanol) it was concluded that an LA-functionalized diblock copolymer (MPEO₄₅-CL₁₀-LA) gave better stabilization of PMMA latices than an LA-functionalized triblock copolymer of comparable composition and HLB value.     

Thermal analyses of graft copolymers of poly (methyl methacrylate) main chain with poly (propylene oxide-b-ethylene oxide) graft chain

Poly(methyl methacrylate-g-(propylene oxide-b-ethylene oxide)) and poly (methyl methacrylate-g-(ethylene oxide-b-propylene oxide)), comprising chemically dissimilar sequences, exhibit intramolecular phase separation. These compositions have applications in coatings and as surface-tension modifiers. This paper presents the thermal behavior of these graft copolymers: separate samples of the homopolymer and of the grafts were also analyzed to provide comparisons. The phase behavior has been analyzed by differential scanning calorimetry and by dynamic-mechanical thermal measurements. Two glass transitions (T_g) are observed, caused by the partial incompatibility within the copolymers. The activation energy of the T_g relaxation process of the main chain is decreased by the graft chain. The influence of poly(propylene oxide-b-ethylene oxide) grafts on the thermal degradation of the poly(methyl methacrylate) (PMMA) main chain was studied by using thermogravimetric analysis. Prolysis of the graft copolymers occurs in three stages and begins on the graft chain and at a lower temperature than the pyrolysis of pure PMMA. Both the phase behavior and the thermal stability are found to depend sensitively on the composition of the copolymer. © 1993 John Wiley & Sons, Inc.     

Poly(dimethylsiloxane)urethane‐co‐poly(methyl methacrylate) with 2,4‐toluene diisocyanate and m‐xylene diisocyanate. I. Compatibility and impact strength of copolymers

In this study, slightly crosslinked poly(dimethylsiloxane)urethane‐co‐poly(methyl methacrylate) (PDMS urethane‐co‐PMMA) graft copolymers based on two diisocyanates, 2,4‐toluene diisocyanate (2,4‐TDI) and m‐xylene diisocyanate (m‐XDI), were successfully synthesized. Glass‐transition behaviors of the copolymers were investigated. Results confirm that PDMS–urethane and PMMA are miscible in the 2,4‐TDI system, but are only partially miscible in the m‐XDI system. The methylene groups adjoining the isocyanate in the m‐XDI system show increased phase‐separation behavior over the 2,4‐TDI system, in which the benzene ring adjoins the isocyanate. The functional group of PDMS–urethane improves the impact strength of the copolymers. The toughness depends on the compatibility of PDMS–urethane and PMMA segments in the copolymers. In the m‐XDI system, the impact strength of the copolymer containing 3.75 phr macromonomer achieves a maximum value (from 13.02 to 22.21 J/m). The fracture behavior and impact strength of the copolymers in the 2,4‐TDI system are similar to that of PMMA homopolymer, although they are independent of the macromonomer content in the copolymer. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 1875–1885, 2002     

Linear viscoelastic behavior of compatibilized PMMA/PP blends

In this work, the morphology and linear viscoelastic behavior of PMMA/PP blends to which a graft copolymer PP‐g‐PMMA has been added was studied. The copolymer concentration varied from 1 to 10 wt % relative to the dispersed phase concentration. The rheological data were used to infer the interfacial tension between the blended components. It was observed that PP‐g‐PMMA was effective as a compatibilizer for PMMA/PP blends. For PP‐g‐PMMA concentration added below the critical concentration of interface saturation, two rheological behaviors were observed depending on the blend concentration: for 70/30 blend, the storage modulus, at low frequencies, increased as compared to the one of the unmodified blend; for 90/10 blend, it decreased. For 90/10 blend, the relaxation spectrum presented an interfacial relaxation time related to the presence of the compatibilizer (τ_β). For PP‐g‐PMMA concentrations added above the critical concentration of interface saturation, the storage modulus of all blends increased as compared with the one of the unmodified blend. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Behavior of aqueous solutions of poly(ethylene oxide-b-propylene oxide) copolymers containing a hydrotropic agent

The effect of the hydrotropic agent, sodium p-toluenesulfonate (NaPTS), was evaluated on the micelle formation process and on phase behavior of aqueous solutions containing poly(ethylene oxide-b-propylene oxide) (PEO–PPO) copolymers. We have studied monofunctional diblock copolymers coupled with hydrocarbons groups (R—PEO—PPO—OH and R—PPO—PEO—OH, where R length is linear C₄ and C_12–14). The critical micelle concentration (CMC) and critical micelle temperature (CMT) values of the aqueous copolymers solutions were obtained from both surface tension versus concentration plots and the dye solubilization method. The influence of the hydrocarbons groups length and PPO segment position in the structure of the copolymers were also analyzed. The same measures were obtained for the aqueous solutions of hydrotropic agent which, in turn, also presented molecular aggregation. The presence of the hydrotropic agent in the aqueous copolymers solutions altered the surface tension of these solutions and the occupied molecular area per copolymer molecule at air–water interface and CMC and CMT values of the copolymers. On the other hand, the aggregation points and the surface tension of the NaPTS solutions were dependent on the copolymer structure and composition. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 69: 2459–2468, 1998     

Natural rubber‐g‐methyl methacrylate/poly(methyl methacrylate) blends

The grafting of the methyl methacrylate (MMA) monomer onto natural rubber using potassium persulfate as an initiator was carried out by emulsion polymerization. The rubber macroradicals reacted with MMA to form graft copolymers. The morphology of grafted natural rubber (GNR) was determined by transmission electron microscopy and it was confirmed that the graft copolymerization was a surface‐controlled process. The effects of the initiator concentration, reaction temperature, monomer concentration, and reaction time on the monomer conversion and grafting efficiency were investigated. The grafting efficiency of the GNR was determined by a solvent‐extraction technique. The natural rubber‐g‐methyl methacrylate/poly(methyl methacrylate) (NR‐g‐MMA/PMMA) blends were prepared by a melt‐mixing system. The mechanical properties and the fracture behavior of GNR/PMMA blends were evaluated as a function of the graft copolymer composition and the blend ratio. The tensile strength, tear strength, and hardness increased with an increase in PMMA content. The tensile fracture surface examined by scanning electron microscopy disclosed that the graft copolymer acted as an interfacial agent and gave a good adhesion between the two phases of the compatibilized blend. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 428–439, 2001     

Influence of the structure and composition on surface tension of aqueous solution of graft copolymers of polyacrylamide backbone and polyalkyleneoxide branches

Polyacrylamide homopolymers and graft copolymers of poly(acrylamide-g-ethylene oxide) and poly(acrylamide-g-propylene oxide) were synthesized, characterized by SEC, FTIR and ¹³C-NMR and the behavior of their aqueous solutions was evaluated by surface tension measurements. By using the macromonomer technique, it is more difficult to incorporate poly(propylene oxide) branches than poly(ethylene oxide) branches. Graft copolymers of polyacrylamide and poly(propylene oxide) showed higher reduction of surface tension than poly(acrylamide-g-ethylene oxide) since they present a structure made up of hydrophilic and hydrophobic segments. Poly(acrylamide-g-propylene oxide) exhibits surfactant behavior, and the surface tension of its aqueous solution depends on the poly(propylene oxide) graft chain length and amount. Received: 9 December 1996/Revised: 15 May 1997/Accepted: 23 May 1997     

Polymeric Linoleic Acid–Polyolefin Conjugates: Cell Adhesion and Biocompatibility

To diversify edible-oil polymer composite, polymeric linoleic acid (PLina) peroxide was obtained by the auto-oxidation of linoleic acid in a simple way for use as a macroinitiator in free radical polymerization of vinyl monomers. Peroxidation, epoxidation, and/or perepoxidation reactions of linoleic acid under air at room temperature resulted in PLina, having soluble fraction more than 91 weight percent (wt%), with molecular weight ranging from 1,644 to 2,763 Da, and containing up to 1.0 wt% of peroxide. PLina initiated the free radical polymerization of ether styrene (S), methyl methacrylate (MMA), or n-butyl methacrylate (nBMA) to give PLina-g-polystyrene (PS), PLina-g-poly-MMA (PMMA), and PLina-g-poly- nBMA (PnBMA) graft copolymers. The polymers obtained were characterized by proton nuclear magnetic resonance (¹H NMR), thermal gravimetric analysis (TGA), differential scanning calorimetry (DSC), and gel permeation chromatography (GPC) techniques. Microstructure of the graft copolymers was observed by using scanning electron microscope (SEM). Graft copolymers obtained contained polymeric linoleic acid in a range between 8.5 and 19.3 mol percent (mol%). PLina-g-PS, PLina-g-PMMA and PLina-g-PnBMA graft copolymer samples were also used in cell culture studies. Fibroblast and macrophage cells were strongly adhered and spread on the copolymer film surfaces. These newly synthesized copolymers were tested for their effects on human blood protein adsorption compared with PMMA graft copolymers containing polymeric soybean oil and polymeric linseed oil; interestingly we observed a dramatic decrease in the protein adsorption on the linoleic acid graft copolymer, which is important in tissue engineering.     

Alcohols Effect on Critic Micelle Concentration of Polysorbate 20 and Cetyl Trimethyl Ammonium Bromine Mixed Solutions

In this research, the micellar behavior of a cationic surfactant, cetyl trimethyl ammonium bromide (CTAB) and an nonionic surfactant, polysorbate 20 (Polyoxyethylene (20) sorbitan monolaurate) in different alcohol solutions media was investigated over the temperature range 293.15–313.15 K. The interaction between two surfactants in binary systems can be determined by calculating the values of their β parameters. The critical micelle concentrations (CMC) of the micelles were determined from the surface tension, the conductivity at different temperatures. The CMC behavior of CTAB and polysorbate 20 was analyzed in terms of the effect of temperature and the increase in the alcohol carbon chain. Changes in the critical micelle concentration of mixed surfactant systems of different alcohol solutions were measured. The CMC decreased sharply as the hydrocarbon chain length of the alcohols becomes larger. This shows that the more hydrophobic alcohols are, the more marked a decrease in CMC is observed.     

Linear and branched polyoxide‐based copolymers: Methods to determine the CMC

Evaluation of the physical–chemical properties of aqueous solutions of nonionic surfactants based on polyoxides can be performed by different methods. Depending on the technique used, there can be a significant variation in the critical micelle concentration (CMC) found. This is related to the sensitivity of the technique regarding the unimers and micelles present in the solution as well as the structure of the surfactant evaluated. In this work, the CMC values of aqueous solutions of linear and branched poly(ethylene oxide‐polypropylene oxide) (PEO‐PPO) block copolymers were determined by tensiometry, fluorescence, and particle size analysis, using copolymers having adjacent structures (that is, hydrophilic and hydrophobic segments located adjacently in the copolymer) and alternating structures. Tensiometry was used to measure the surface tension as a function of the copolymer concentration in aqueous solution. Fluorescence was used to determine the fluorescence intensity of pyrene to plot the graphs of the I₁/I₃ and I_E/I_M relations according to the surfactant concentration. Finally, particle size analysis was used to determine the diffusion coefficient of the particles. The results showed that the fluorescence and particle size techniques provide lower (and mutually concordant) CMC values and can be considered more precise because these methods directly analyze the bulk of the solution. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Synthesis and characterization of anionic graft copolymers containing poly(ethylene oxide) grafts

Graft copolymers containing poly(ethylene oxide) side chain attached to maleic anhydride‐alt‐vinyl methyl ether (MA‐VME) copolymer were prepared by coupling MA‐VME and poly(ethylene glycol) monomethyl ether (MPEG) by esterification in DMF at 90°C. MPEG and dodecyl alcohol (DA) were grafted onto MA‐VME copolymer in o‐xylene at 140°C in the presence of p‐toluene sulfonic acid as catalyst. The molecular weights of MPEG were found to influence the rate of the grafting reaction and the final degree of conversion. The graft copolymers were characterized by IR, GPC, and ¹H‐NMR. DSC was used to examine thermal properties of the graft copolymers. The analysis indicates that grafts have phase‐separated morphology with the backbone and the MPEG grafts forming separate phases. The properties in aqueous solutions of these grafts were studied with respect to aggregation behavior and viscometric properties. In aqueous solution, the polymers exhibited polyelectrolyte behavior (i.e., a dramatic increase of the viscosity upon neutralization). Graft copolymers with DA have lower viscosities. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 1138–1148, 2002     

Surface microphase separation in PDMS‐b‐PMMA‐b‐PHFBMA triblock copolymer films

Well‐defined poly(dimethylsiloxane)‐block‐poly(methyl methacrylate)‐block‐poly(2,2,3,3,4,4,4‐heptafluorobutyl methacrylate) (PDMS‐b‐PMMA‐b‐PHFBMA) triblock copolymers were synthesized via atom transfer radical polymerization (ATRP). Surface microphase separation in the PDMS‐b‐PMMA‐b‐PHFBMA triblock copolymer films was investigated. The microstructure of the block copolymers was investigated by transmission electron microscopy (TEM) and atomic force microscopy (AFM). Surface composition was studied by X‐ray photoelectron spectroscopy (XPS). The chemical composition at the surface was determined by the surface microphase separation in the PDMS‐b‐PMMA‐b‐PHFBMA triblock copolymer films. The increase of the PHFBMA content could strengthen the microphase separation behavior in the PDMS‐b‐PMMA‐b‐PHFBMA triblock copolymer films and reduce their surface tension. Comparison between the PDMS‐b‐PMMA‐b‐PHFBMA triblock copolymers and the PDMS‐b‐PHFBMA diblock copolymers showed that the introduction of the PMMA segments promote the fluorine segregation onto the surface and decrease the fluorine content in the copolymers with low surface energy. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Premade vs. reactively formed compatibilizers for PMMA/PS melt blends

The efficiency of two compatibilization methods, adding premade copolymers versus in situ formation of copolymers, were compared by evaluating the minor phase size and size distribution. Premade diblock copolymers were formed by coupling amine terminal polystyrene (PS-NH₂) with anhydride terminal poly(methyl methacrylate) (PMMA-An) in solution. Mid-functional PMMA was coupled with the PS-NH₂ to form graft copolymers. The same block and graft copolymers were formed in situ during melt blending. After mixing, the particle size and distribution were analyzed by transmission electron microscope (TEM). While both methods compatibilized blends, in situ formation reduced the minor phase size further. For the reactive case, graft copolymers are slight better than the block ones. This is attributed to a greater capacity for reducing interfacial tension. For the premade case, block copolymers compatibilize better at low copolymer concentration while graft copolymers work better at high concentration. As the amount of block copolymers added into the blends increases, the number of micelles increases significantly. This is believed to be the reason why premade copolymers are less capable of compatibilizing blends than the reactively formed ones.     

Effect of graft chain length of the stabilizer on dispersion polymerization of methyl methacrylate in petrol

To carry out dispersion polymerization of methyl methacrylate (MMA) in petrol, we have used a poly(MMA) grafted-poly(12-hydroxystearic acid) copolymer as the stabilizer. This special copolymer was prepared as a solution in a mixture of ethyl acetate and butyl acetate solvents. We investigated the effect of graft chain length of the stabilizer on the dispersion polymerization in petrol. We synthesized the stabilizer copolymer with n = 1–4 and determined the rate and the molecular weight of the PMMA formed. There is no dispersion polymerization for n = 1. However, for any other n, for a given stabilizer concentration, as the chain length of the graft is increased, the molecular weight as well as the rate of PMMA formation increases. As opposed to this for a given graft length as the concentration of the stabilizer increases, the molecular weight of PMMA first rises, but for a larger concentration, it begins to fall after undergoing a maximum. In this work, we modeled the heterogeneity of the reaction mass and proposed a mathematical model for dispersion polymerization of MMA in petrol. The computer results are found to conform to the experimentally observed molecular weight of the PMMA. © 1993 John Wiley & Sons, Inc.     

Characterization and thermal properties of poly(n‐butyl acrylate‐g‐styrene) graft copolymers

Poly(butyl acrylate‐g‐styrene) graft copolymers were prepared by free‐radical polymerization using a polystyrene macromonomer carrying a methacryloyloxy group at the chain end and they were characterized by size‐exclusion chromatography, and Fourier transform infrared spectroscopy. Glass transition temperatures and degradation behavior were determined by thermal analysis. Only a single glass transition temperature was observed for the resulting graft copolymers, indicating the miscibility between the poly(styrene) phase and poly(butyl acrylate) (pBA) phase in the graft copolymer. The incorporation of polystyrene segments in the graft copolymer improved the thermal stability of pBA and enhanced the apparent activation energy for the thermal degradation of pBA. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 783–789, 2001     

Intermolecular and intramolecular hydrogen bonding of poly(dimethylsiloxane)urethane‐graft–poly(methyl methacrylate) copolymers based on 2,4‐TDI and m‐XDI

In this study, poly(dimethylsiloxane)urethane–graft–poly(methyl methacrylate) (PDMS urethane–g–PMMA) copolymers with low crosslinking density were synthesized. Glass transition temperatures of the copolymers were investigated by dynamic mechanical analysis (DMA) and differential scanning calorimetry (DSC). Results confirm that PDMS urethane–g–PMMA is miscible in the 2,4‐TDI (2,4‐ toluene diisocyanate) system, whereas it is partially miscible in the m‐XDI (m‐xylene diisocyanate) system. Free, intra‐ (urethane–urethane), and inter‐ (urethane–ester) association hydrogen bonding exist in the urethane group of copolymers. The inter‐association hydrogen bonding can improve the compatibility of the copolymer components. The relationship between the frequency shift and enthalpy confirm the distribution of hydrogen bonding in the macromonomer and copolymer. Ninety percent of the hydrogen bonding is by interassociation in the 2,4‐TDI system. The intra‐association hydrogen bonding in the m‐XDI system is higher than that in the 2,4‐TDI system. Consequently, aggregation may occur easily in the siloxane‐grafted chain in the m‐XDI system. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 962–972, 2002     

The effects of PC‐PMMA block copolymer on the compatibility and interfacial properties of PC/SAN blends

Block copolymers of polycarbonate (PC) and polymethylmethacrylate (PMMA), PCb‐PMMA, were examined as compatibilizers for blends of PC with styrene‐co‐acrylonitrile (SAN) copolymer. PC‐b‐PMMA was added to blends of PC with SAN containing various amounts of AN. The average diameter of the dispersed particles was measured with an image analyzer, and the interfacial properties of the blends were analyzed with an imbedded fiber retraction (IFR) test and an asymmetric double cantilever beam fracture test. The average particle size and interfacial tension of the PC/SAN blends reached a minimum value when the SAN copolymer contained about 24 wt% AN. A maximum in the adhesion energy was also observed at the same AN content. Interfacial tension and particle size were further reduced by adding PC‐b‐PMMA to the PC/SAN blends. Fracture toughness of the blends was also improved by enhancing the interfacial adhesion by the addition of PC‐b‐PMMA. The addition of PC‐b‐PMMA copolymer was more effective at improving the interfacial properties of PC/SAN blends than was varying the AN content of the SAN copolymers. The interfacial properties of the PC/SAN blends were optimized by adding a block copolymer and using an SAN copolymer that had minimum interaction energy with PC.     

Production of carboxyl-containing derivatives of polymethyl methacrylate and polycaproamide graft copolymer

In studying heterophase alkaline hydrolysis of ester groups in graft PMMA chains, the role of the structure of the polymer in the macromolecular reaction in the solid phase was revealed. A decrease in the degree of conversion of graft PMMA with an increase in its content in PCA—PMMA graft copolymer, caused by a change in the packing density of the graft chains, was established. The highest degree of saponification was attained in using graft copolymers containing 25–35% graft PMMA. Chemisorption, carboxyl-containing polycaproamide fibre with a SEC for NaOH of 1.3 mmole/g was obtained as a result of saponification of PCA—PMMA graft copolymers. Translated from Khimicheskie Volokna, No. 5, pp. 22–25, September–October, 2008.     

Synergism and Phase Behavior of Alcohol Polyoxyethylene Ether Acetate and Cationic Surfactant-Mixed Systems

Synergism in mixed micelle formation and surface tension reduction efficiency and the ternary phase behavior of anionic surfactant (alcohol polyoxyethylene ether acetate containing 10 ethylene oxide group and a fatty chain of C_16–18) with cationic surfactants (dodecyldimethylbenzyl ammonium chloride and lauryltrimethyl ammonium chloride) were investigated. Surface tension of the systems at different molar ratios was studied in detail and the interaction parameters of each system were calculated. The results show that both systems have lower values of critical micelle concentration (CMC) and γ_cmc than individual surfactants especially at equal ratio between cationic and anionic surfactants. Both systems present synergism in mixed micelle formation and surface tension reduction efficiency. The ternary phase behavior of the two systems was investigated using a polarized microscope. The micellar phase and lamellar phase were observed in both systems and the coexisting phase was only observed in the dodecyldimethylbenzyl ammonium chloride system.     

Surface and Aggregation Properties of Synthesized Cetyl Alcohol Based Bis-Sulfosuccinate Gemini Surfactants in Aqueous Solution

A series of cetyl alcohol based anionic bis‐sulfosuccinate gemini surfactants (BSGSCA1,4; BSGSCA1,6 and BSGSCA1,8) with different spacer lengths was prepared using dibromoalkanes. The surfactant structure was elucidated using elemental analysis, Fourier transform infrared spectroscopy (FT‐IR) and nuclear magnetic resonance spectroscopy (NMR). Surface tension measurements were used to determine the critical micelle concentration (CMC), the surface tension at the CMC (γ_CMC), surface pressure at the CMC (π_CMC) and efficiency of adsorption (pC20). On the basis of surface studies, the CMC and γ_CMC decreases with increasing length of the spacer group. The micelle aggregation number, determined by fluorescence quenching studies, increases with increasing surfactant concentration above the CMC. The micropolarity in the micelle increases with increasing length of the spacer and decreases with increasing surfactant concentration.