Effect of acrylic acid on water-whitening resistance of polyacrylate latex films and its mechanism

Two groups of polyacrylate latexes with higher (21 ~ 35 °C) or lower (−33 ~ −43 °C) glass transition temperatures (T_g) were prepared by adjusting the monomer ratio of butyl acrylate (BA) and styrene (St), and the effect of acrylic acid (AA) on water-whitening resistance of these latex films was investigated. It was found that the water-whitening resistance of the two groups of latex films was different. With the increase of AA content, the water whitening resistance of the latex films with higher T_g continued to improve, while that of the latex films with lower T_g increased first and then decreased. A series of characterizations, such as light transmittance, water whitening, water absorption, static water contact angle, surface morphology, and optical microscope test of the latex film, and so forth, showed that the reason for this difference was that under higher AA content (≥5%), compared with the polyacrylate latex films with lower T_g, the latex films with higher T_g could reach the saturation state of water absorption quickly, and water in these latex films exhibited continuous and large area distribution, rather than formation of many so-called micro- or nano-scale water sacs that can scatter light as found in the latex films with lower T_g.     

Synthesis of ambient temperature self-crosslinking VTES-based core–shell polyacrylate emulsion via modified micro-emulsion polymerization process

Modified micro-emulsion polymerization was successfully used to synthesize a kind of ambient temperature self-crosslinking core–shell emulsion, consisting of polyacrylate core and vinyltriethoxysilane (VTES) modified polyacrylate shell, by varying the ratio of soft monomer (BA) and hard monomer (MMA) which is different in the core and shell. The emulsion and its film formed at ambient temperature were characterized by attenuated total reflectance-fourier transform infrared spectroscopy (ATR-FTIR), transmission electron microscopy (TEM), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). Core–shell structure was clearly shown in TEM micrographs, and two distinct glass transition temperatures (T _g) were confirmed by DSC analysis. Lower T _g of core phase analyzed by DSC and self-crosslinking properties of VTES characterized by crosslinking degree cause latex particles form continuous film at ambient temperature. Thermal and mechanical properties and the surface properties of the latex films were also investigated. Results showed that the core–shell latex films containing 5 and 7.5 % VTES exhibited higher thermal stability, better mechanical properties, higher contact angle, and water resistance compared with pure polyacrylate film.     

Role of acrylic acid in the synthesis of core‐shell fluorine‐containing polyacrylate latex with spherical and plum blossom‐like morphology

The core‐shell fluorine‐containing polyacrylate latex was successfully synthesized by two‐stage semicontinuous emulsion copolymerization of methyl methacrylate (MMA), butylacrylate (BA), acrylic acid (AA), and dodecafluoroheptyl methacrylate (DFMA). The fluorine‐containing polyacrylate latex was characterized by Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), dynamic light scattering (DLS), zeta potential, thermal gravimetric analysis (TGA), differential scanning calorimetry (DSC). The effects of AA content on monomer conversion, polymerization stability, particle size, corsslinking degree, carboxyl groups distributions (latex surface, aqueous phase or buried in latex), as well as mechanical properties and water absorption rate of latex film were investigated. The obtained fluorine‐containing polyacrylate latex exhibited core‐shell structure with a particle size of 120–150 nm. The introduction of AA was beneficial for the increase of monomer conversion and the polymerization stability, and had little effects on the mechanical property of latex film. However, the hydrophilicity of AA made the water resistance of latex film get bad. With the increase of AA content, the carboxyl groups preferred to distribute on aqueous phase, and the possibility of homogeneous nucleation increased and more oligomers particles were formed. Moreover, the oligomers would distribute to the latex and continued to grow up, making the latex morphology changed from spherical to plum blossom‐like. The core‐shell latex had two T_g corresponding to the rubber polyacrylate core and hard fluorine‐containing polyacrylate shell, and the latex film possessed excellent thermal stability. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42527.     

Preparation and characterization of stable and high solid content St/BA emulsifier-free latexes in the presence of AMPS

Stable and high solid content (about 50 wt%) St/BA emulsifier-free latexes were successfully synthesized using emulsifier-free emulsion polymerization with the addition of a small amount of reactive emulsifier AMPS. Properties of the latexes, such as the average particle diameter and its distribution, the morphology of latex particles, and stability were investigated. Physical properties of the latex films, i.e., glass transition temperature (T _g), water resistance, and solvent resistance were investigated as well. The size of latex particles is 400–600 nm in diameter, which is larger than that prepared by conventional emulsion polymerization. And the particle size distribution is narrow and uniform. It was found that the diameter of the latex particles decreases with the increasing content of the initiator KPS and the reactive emulsifier AMPS. Compared with the film prepared by conventional emulsion polymerization, water resistant and solvent resistant of the films prepared by emulsifier-free emulsion polymerization are improved greatly.     

BA‐MMA‐POMA copolymer latexes prepared by using HMPS polymerizable emulsifier

BA‐MMA‐POMA copolymer latex was successfully prepared by soap‐free emulsion polymerization of 2‐(perfluoro‐(1,1‐bisisopropyl)‐2‐propenyl)oxyethyl methacrylate(POMA) with butyl acrylate(BA), methyl methacrylate (MMA) initiated by K₂S₂O₈ in the water. POMA was synthesized from the intermediate perfluoro nonene and 2‐hydroxyethyl methacrylate as the staring reactants. The structure of BA‐MMA‐POMA copolymer latex was investigated by Fourier transform infrared (FTIR). The characteristics of the film such as hydrophobicity and glass transition temperature were characterized with the contact angle and differential scanning calorimetry respectively. The influences of the amount of the fluorinated monomer and the initiator on the soap‐free emulsion polymerization and performance of the latex were studied. In addition, comparison with the latex prepared by the conventional emulsifier SDBS is investigated. Results show that the hydrophobicity and glass transition temperature (T_g) of the latex are increased when the fluorinated monomer is introduced to copolymerize with other monomers. The hydrophobicity can be improved further with heating. Compared with the latices prepared by using SDBS emulsifier, the latices prepared by using HMPS emulsifier have larger particle size, higher surface tension. However, the difference of their T_g is extremely minute. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

核壳型纳米SiO2/含氟聚丙烯酸酯复合乳液的合成与表征

采用原位乳液聚合法,在可聚合阴离子乳化剂/非离子乳化剂复配体系下,以γ-甲基丙烯酰氧丙基三甲氧基硅烷(KH-570)改性的纳米SiO2、甲基丙烯酸甲酯(MMA)、丙烯酸丁酯(BA)、丙烯酸(AA)等为核相组成,以MMA、BA及甲基丙烯酸十二氟庚酯(DFMA)为壳相单体,合成纳米SiO2/含氟聚丙烯酸酯复合乳液.考察了纳...     

Effect of polymer latexes with varied glass transition temperature on cement hydration

Influence of styrene‐acrylate latexes with varied glass transition temperature (T_g) on cement hydration was studied and the mechanism was analyzed. Results show that polymer latexes with varied T_g retard cement hydration to different extents. Specifically, low T_g polymer shows stronger retardation effect than the high T_g polymer. Despite similar surface charges, colloidal particles with lower T_g exhibit higher affinity to surface of cement grains than the high T_g polymer, indicated by the higher adsorption amount and denser covering layer. The low T_g polymer experiences particle packing, deforming, and film forming processes along with the consumption of water during cement hydration, which eventually produces a covering layer of polymer surrounding cement grains. However, for the high T_g polymer, film forming process is absent. Consequently, the higher adsorption amount and the film‐formation process along with cement hydration are the two reasons for the stronger retardation effect of the low T_g polymer. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45264.     

The diacetone acrylamide crosslinking reaction and its control of core‐shell polyacrylate latices at ambient temperature

Self crosslinkable core‐shell polyacrylate latices (PAs) cured at ambient temperature were synthesized by semicontinuous‐seeded emulsion polymerization with diacetone acrylamide (DAAM) and adipic dihydrazide (ADH) as crosslinkable monomers. The influences of DAAM monomer mass content, neutralizer, and curing temperature on the properties of self crosslinkable core‐shell latices and the keto‐hydrazide crosslinking were discussed. The spectroscopic techniques such as Fourier transform infrared spectroscopy (FTIR), differential scanning calorimeter (DSC), atomic force microscopy (AFM), transmission electron microscopy (TEM), and contact angle instruments were used to determine the structure and properties of PAs. The water evaporating rate during the film‐forming process of self crosslinkable core‐shell latices was also investigated. FTIR analyses demonstrate that the keto‐hydrazide crosslinking reaction does not occur in the latex environment but occurs at ambient temperature with the evaporation of water during the film‐forming process. The results of DSC show that the core‐shell crosslinkable PAs have two glass transition temperatures (T_g), and T_gs of crosslinked film are higher than that of non crosslinked fim. Moreover, the keto‐hydrazide reaction is found to be acid catalyzed and favored by the loss of water and the simultaneous decrease in pH arising from the evaporation of ammonia or amines during film‐forming process. Hence, in the volatile ammonia or amines neutralized latices, the latex pH value adjusted to 7–8, which not only ensure the crosslinkable latex with good storage stability but also obtain a coating film with excellent performances by introducing the keto‐hydrazine crosslinking reaction. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Synthesis and performance characteristics of a water‐based polyacrylate microemulsion for UHMWPE fiber adhesive coating

The water‐based polyacrylate microemulsion for ultrahigh molecular weight polyethylene (UHMWPE) fibers adhesive coating was synthesized by the emulsion polymerization of methyl methacrylate (MMA), butyl acrylate (BA), acrylic acid (AA), and hydroxyethyl acrylate (HEA) in the presence of a composite of sodium lauryl sulfate (SLS), OP‐10, and n‐octyl alcohol (NOA) as the emulsifier. The effects of the mass fraction of emulsifier and the reaction time on the properties of emulsion and its membrane were investigated. When m(BA) : m(MMA) : m(AA) : m(HEA) was 50 : 50 : 3 : 10 (wt ratio) and the mass fraction of emulsifier was 13 wt % and the reaction time was 3 h at 80°C, the latex particle diameter was 30 nm tested by transmission electron microscope (TEM). The Fourier transform infrared (FTIR) spectrometer and differential scanning calorimeter (DSC) were used to characterize the chemical structure and the glass transition temperature (T_g) of microemulsion membrane. The application results showed that this microemulsion was an ideal adhesive coating for UHMWPE fibers. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci, 2006     

Film formation from polymer dispersions

The coalescence of a poly(vinylidene chloride/methyl acrylate/acrylic acid) latex was found to occur only above the T_g. The various theories of film formation from polymer dispersions attribute latex coalescence to three types of forces: the pressure due to the polymer–air interface, the pressure due to a polymer–water interface, and the pressure due to capillary action. Analysis of the forces indicates that none are sufficient to cause coalescence below T_g while any, or all, may cause coalescence above T_g.     

Fabrication and properties of polysilsesquioxane-based trilayer core–shell structure latex coatings with fluorinated polyacrylate and silica nanocomposite as the shell layer

Polysilsesquioxanes (PSQ)-based core–shell fluorinated polyacrylate/silica hybrid latex coatings were synthesized with PSQ latex particles as the seeds, and methyl methacrylate, butyl acrylate, 3-(trimethoxysilyl) propyl methacrylate (MPS)-modified SiO₂ nanoparticles (NPs), 1H,1H,2H,2H-perfluorooctyl methacrylate (PFOMA) as the shell monomers by emulsifier-free miniemulsion polymerization. The results of Fourier transform IR spectroscopy, transmission electron microscopy, and dynamic light scattering suggested the obtained hybrid particles emerged with trilayer core–shell pattern. Contact angle analysis, x-ray photoelectron spectroscopy, and atom force microscopy results indicated that the hybrid film containing SiO₂ NPs showed higher hydrophobicity, lower surface free energy and water absorption, in comparison with the control system (without SiO₂ NPs). Compared with the control system, the hybrid latex film containing SiO₂ NPs in the fluorinated polyacrylate shell layer showed the higher content of fluorine atoms and a rougher morphology on the film surface. Additionally, thermogravimetric analysis demonstrated the enhanced thermostability of PSQ-based nanosilica composite fluorinated polyacrylate latex film.     

Synthesis and properties of fluorine–silicon modified polyacrylate hybrid latex particles with core–shell structure obtained via emulsifier‐free emulsion polymerization

A core–shell fluorine–silicon modified polyacrylate hybrid latex was successfully prepared via emulsifier‐free emulsion polymerization. The chemical composition and core–shell morphology of the resultant hybrid particles were investigated using ¹H NMR and Fourier transform infrared spectroscopies and transmission electron microscopy (TEM), respectively. TEM analysis indicated that the core–shell hybrid particles were uniform with narrow size distributions. The particle size and zeta potential decreased with an increase of alkylvinylsulfonate surfactant from 2.5 to 6.0 wt%. X‐ray photoelectron spectroscopy revealed that fluorine concentrated preferentially at the film surface during a film‐formation process. The film formed from the fluorine–silicon modified polyacrylate showed much higher thermal stability than a film formed from polyacrylate and fluorine‐modified polyacrylate. Contact angle results showed that a finished fabric had remarkable water repellency. © 2015 Society of Chemical Industry     

Studies on the preparation of stable and high solid content emulsifier‐free latexes and characterization of the obtained copolymers for MMA/BA system with the addition of AHPS

3‐Allyloxy‐2‐hydroxyl‐propanesulfonic (AHPS) salt was synthesized and used as a hydrophilic comonomer for the methyl methacrylate (MMA) and n‐butyl acrylate (BA) emulsifier‐free emulsion copolymerization system to obtain latices of stable and high‐solid content. Properties of the latices, such as flow behavior, stability, and final diameter of the latex particles were studied. In addition, physical properties of the obtained copolymers, such as glass transition temperature (T_g), stress–strain behavior, and water resistance were investigated. With the addition of AHPS, the latices of stable and high‐solid content (as high as 60%) were prepared. Flow of the latices follows the law of the Bingham body. The final diameter of the latex particles is 0.3–0.5 μm in diameter, which is larger than that of the conventional latex particles and decreases with the increase of AHPS and potassium persulfate (KPS) concentration. All the copolymers are atactic polymers, showed as single T_g on dynamic mechanical analysis spectrum. Compared with the copolymers that were prepared by surfactant emulsion polymerization, tensile strength, as well as water resistance is greatly improved. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 79: 21–28, 2001     

Effect of sintering on surface chemistry and surface energy of pigmented latex coatings

Drying in the absence of water (sintering) of pigmented coatings made of styrene–butadiene (SB) latex and kaolin clay at different levels of pigmentation was investigated. As found from X-ray photoelectron spectroscopy, sintered coatings showed a higher SB area percent on the surface than did latex with a high glass-transition temperature (T_g) and dried at room temperature. This was a result of latex spreading at the surface. Sintering the high-T_g coatings that were dried at room temperature caused a decrease in the surface energy. Drying in the presence of water (wet coalescing) was compared to drying in the absence of water (sintering). Even though sintered coatings were more porous and had higher gloss, no significant difference was found in the SB/clay ratio at the surface or in the surface energy above the critical pigment volume concentration (CPVC). However, at and below CPVC, the sintering process yielded a higher SB content at the surface and a lower surface energy than the wet-coalescing process. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 968–975, 2001     

Double in-situ synthesis of polyacrylate/nano-TiO2 composite latex

Polyacrylate/nano-TiO₂ composite latex was prepared via double in-situ polymerization using acrylamide (AM), vinyl acetate (VAc), butyl acrylate (BA) and methyl methacrylate (MMA) as monomers, tetrabutyl titanate (Ti(OBu)₄) as precursor of TiO₂. The morphology, structure and distribution of composite latex were characterized by Transmission Electron Microscope (TEM), Fourier Transform Infrared Spectroscopy (FTIR), Dynamic Light Scattering (DLS) and X-Ray Diffraction (XRD). The thermal stability, anti-yellowing and antibacterial properties of composite latex were also investigated. The results showed that nano-TiO₂ consisted in polyacrylate latex and it was located on the surface of latex particles. The average particle size of polyacrylate/nano-TiO₂ composite latex was 156.6 nm, which was bigger than that of pure polyacrylate (125.1 nm). The introduction of nano-TiO₂ improved the thermal stability, anti-yellowing and antibacterial properties of the latex film. At last, the polyacrylate/nano-TiO₂ composite latex was applied in leather finishing. Compared with polyacrylate latex, the properties of the leather finished by polyacrylate/nano-TiO₂ composite latex were enhanced: water vapor permeability increased by 58% and water uptake decreased by 3.52%.     

Improvement of film properties of vinyl acetate based emulsion polymers by using different types of maleic acid diesters

Two types of maleic acid diesters, dibutyl maleate (DBM) and dioctyl maleate (DOM) were used as comonomers in semicontinuous emulsion copolymerization of vinyl acetate (VAc) in order to improve the film properties of poly(vinyl acetate), PVAc emulsion polymer. The effects of the comonomer type and comonomer ratio on minimum film forming temperature (MFFT), glass transition temperature (T_g), polymer structure, molecular weights, water contact angle and water resistance of PVAc latex films were examined. It was found that MFFT and T_g of the PVAc emulsion polymer decreased by the presence of the maleic acid disters in copolymer composition. This decrease was more affected by the increasing content and alkyl chain length of the comonomers. The molecular weights of the emulsion polymers were also affected by the comonomers and their ratios. Moreover, hydrophobicity and water resistance of the PVAc latex films were increased by using DBM and DOM as comonomer.     

Film‐forming behavior and mechanical properties of colloidal silica/polymer latex blends with high silica load

In this article, silica sol (diameter: 8–100 nm) and polymer latex (T_g < 25°C) were mixed and dried at room temperature to prepare nanocomposite films with high silica load (≥50 wt %). Effects of silica size, silica load, and the T_g of the polymer on the film‐forming behavior of the silica/polymer latex blend were investigated. The transparency, morphology, and mechanical properties of the nanocomposite films were examined by UV–Vis spectroscopy, SEM, and nanoindentation tests, respectively. Transparent and crack‐free films were produced with silica loads as high as 70 wt %. Thirty nanometers was found to be the critical silica size for the evolution of film‐forming behavior, surface morphology, and mechanical properties. Colloidal silica particles smaller than this critical size act as binders to form strong silica skeleton. This gives the final silica/polymer nanocomposite film its porous surface and high mechanical strength. However, silica particles with sizes of 30 nm or larger tend to work as nanofillers rather than binders, causing poor mechanical strength. We also determined the critical silica load appeared for the mechanical strength of silica/polymer film at high silica load. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Synthesis and characterization of fluorine-containing poly-styrene-acrylate latex with core–shell structure using a reactive surfactant

Fluorine-containing poly-styrene-acrylate (PSA) latex with core–shell structure was successfully synthesized by seeded semicontinuous emulsion polymerization using fluorine monomer Actyflon-G₀₄ and reactive emulsifier DNS-86. The chemical composition, morphology of latex, and surface composition of the latex film were characterized by Fourier transform infrared spectra, transmission electron microscopy, and X-ray photoelectron spectroscopy, respectively. The stability properties of latex were tested by Ca²⁺, centrifugal and mechanical stability tests, and the latex film was studied by water contact angle, water absorption ratio, and thermo-gravimetric analysis. The results show that fluorine-containing PSA latex particles with crosslinked core and crosslinked shell structure have excellent stability properties, and the film of latex has excellent water repellency, thermal stability, and chemical resistance properties when the amount of fluorine monomer was only 8.0 wt%.     

Cationic fluorinated polyacrylate core‐shell latex with pendant long chain alkyl: Synthesis,film morphology,and its performance on cotton substrates

We synthesized a novel cationic fluorinated polyacrylate latex (FLDH) with pendant long chain alkyl by copolymerization of perfluoroalkyl ethyl acrylate, lauryl methacrylate, dimethylaminoethyl methacrylate, and 2‐hydroxypropyl acrylate. FTIR, ¹H‐NMR, TEM, DSC, and TGA were used to characterize the as‐prepared FLDH. Then fine morphology, components, and hydrophobicity of films on silicon wafer and cotton substrates were investigated by scanning electron microscope, field emission scanning electronic microscope, atomic force microscope, X‐ray photoelectron spectroscopy (XPS), contact angle meter, etc. Results showed that the FLDH particles had quasi‐spherical core‐shell structure with an average diameter of 144 nm. The core‐shell FLDH film thus had two T_g and its thermal property was improved compared to fluorine‐free acrylate latex. FLDH could form a film on both the cotton fiber and silicon wafer substrate. At an amplification of <60,000 (of the original fiber) and the observation rule (working distance) of >100 nm, FLDH showed a smooth resin film on the treated fabric/fiber surface. However, as the observation rule decreased to 2 nm‐almost a molecular lever‐the FLDH film mostly exhibited an inhomogeneous structure and uneven morphology in its atomic force microscope images. There were many low or high peaks in FLDH topography. Consequently, in 5 μm² scanning field, the root mean square roughness of FLDH film reached to 0.506 nm. XPS analysis indicated the perfluoroalkyl groups had the tendency to enrich at the surface. In addition, water contact angle of the treated fabric could attain 146.2°. FLDH do not influence whiteness of the treated fabric but will make it slightly stiff at high doses. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci., 2013     

Synthesis,film morphology,and performance of cationic fluorinated polyacrylate emulsion with core-shell structure

A novel cationic fluorinated polyacrylate emulsion (CFBDH) was prepared by polymerization of dodecafluoroheptyl methacrylate (DFMA) with butyl acrylate (BA), dimethylaminoethyl methacrylate (DM), and 2-hydroxypropyl acrylate (HpA) via seeded emulsion polymerization. Chemical structure, particle morphology, glass transition temperature, and thermal property of resultant CFBDH were characterized by FTIR, ¹H-NMR, TEM, DSC, and TGA, respectively. The as-synthesized product was utilized to treat the clean glass sheet and cotton fabric substrates, then morphology, components, hydrophobicity, and other performances of films on those substrates were investigated by SEM, AFM, XPS, and contact angle meter, etc. Results show that the target product possesses anticipative structure and its latex particles have uniform spherical core-shell structure with an average diameter of 126 nm. The core-shell CFBDH latex film thus has two T_g and its thermal property has been improved due to the introduction of fluorine-containing acrylate monomer. The CFBDH film on cotton fabric surface seems to be smooth compared to the blank by SEM. However, the CFBDH film on silicon-wafer is inhomogeneous and has many low or high peaks. At 2 nm data scale and in 1 μm² scanning field, the root mean square roughness of CFBDH film reaches to 0.205 nm. XPS analysis indicates the perfluoroalkyl groups have the tendency to enrich at the film-air interface. In addition, CFBDH can provide good hydrophobicity for the treated fabric and do not influence whiteness of the treated fabric indeed. However it will make the treated fabric slightly stiff at high doses. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012