Preparation and characterization of self-crosslinking acrylic emulsion with different fluorocarbon chain lengths

Purpose Fluorine materials have received the keen attention of many researchers because of their water repellency and low surface free energy. The purpose of this paper is to prepare self-crosslinking fluorocarbon polyacrylate latexes containing different fluorocarbon chain lengths by semi-continuous seeded emulsion polymerization technology. Design/methodology/approach Methyl methacrylate (MMA), butyl acrylate (BA), hydroxypropyl methacrylate (HPMA) and fluorine-containing monomers were used as main monomers. The fluorine-containing monomers included hexafluorobutyl methacrylate (HFMA), dodecafluoroheptyl methacrylate (DFMA) and trifluorooctyl methacrylate (TFMA). Potassium persulfate (KPS) was used as thermal decomposition initiator, non-ionic surfactant alkyl alcohol polyoxyethylene (25) ether (DNS-2500) and anionic surfactant sodium dodecylbenzene sulfonate (SDBS) as mixed emulsifier. Findings Through optimizing the reaction conditions, the uniform and stable latex is gained. The polymer of structure was characterized by Fourier transform infrared spectroscopy (FTIR). Thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and contact angle (CA) were tested on latex films. The particle size and distribution range of emulsion were tested with nano particle size analyzer. After comprehensively comparing the latexes and films prepared by HFMA, DFMA and TFMA, the performance of DFMA monomer modified is better. Originality/value The self-crosslinking acrylic emulsion is prepared via semi-continuous seeded emulsion polymerization, which methyl methacrylate (MMA), butyl acrylate (BA), hydroxypropyl methacrylate (HPMA) and fluorine-containing monomers were used as main monomers. The fluorine-containing monomers were composed of hexafluorobutyl methacrylate (HFMA), dodecafluoroheptyl methacrylate (DFMA) and trifluorooctyl methacrylate (TFMA). Potassium persulfate (KPS) was used as thermal decomposition initiator, non-ionic surfactant alkyl alcohol polyoxyethylene (25) ether (DNS-2500) and anionic surfactant sodium dodecylbenzene sulfonate (SDBS) as mixed emulsifier. There are two main innovations. One is that the self-crosslinking acrylic emulsion is prepared successfully. The other is that the effects of monomers containing different fluorocarbon chain lengths on polyacrylate, such as monomer conversion rate, coagulation rate, mechanical stability, chemical stability, emulsion particle size and storage stability, are studied in detail.

Preparation and characterization of self-cross-linking long fluorocarbon polyacrylate latex modified by silane cross-linker

Purpose Silane cross-linkers have been used to strengthen the mechanical stabilities and friction resistance of plastic products. Therefore, the effect of silane cross-linkers on latex has been studied through preparing modified self-cross-linking long fluorocarbon polyacrylate latex. In this paper, nonionic surfactant alcohol ether glycoside (AEG1000) and anionic polymerizable surfactant 1-allyloxy-3-(4-nonylphenol)-2-propanol polyoxyethylene (10) ether ammonium sulfate (DNS-86) acted as mixed emulsifier and 3-(methacryloyloxy) propyltrimethoxysilane (KH-570) and bis (2-ethylhexyl) maleate (DOM) were used as functional monomers. Design/methodology/approach The modified acrylate polymer latex was synthesized through the semi-continuous seeded emulsion polymerization with methyl methacrylate (MMA), butyl acrylate (BA), dodecafluoroheptyl methacrylate (DFMA) and hydroxypropyl methacrylate (HPMA) as main monomers. Potassium persulfate (KPS) was applied to initiate polymerization reaction, nonionic surfactant AEG1000 and DNS-86 acted as emulsifier, KH-570 and DOM were used as functional monomers, respectively. Findings The optimum conditions of synthesizing the modified latex were the following. The mass ratio of monomers containing MMA, BA, DFMA, HPMA, KH-570 and DOM was 13.58:13.58:0.90:1.20:0.15:0.60, the usage of initiator KPS was 0.5% of the total weight of monomers and the amount of emulsifier was 7% of all monomers with AEG1000:DNS-86 = 1:1. The results indicated that the conversion of monomer was 99% and the coagulation was about 2.0%. Originality/value The resultant latex was modified silane cross-linker KH-570 and DOM, which positively affected the comprehensive properties of latex and its film. Apart from this, the novel mixed emulsifier was used to improve the size and distribution of latex particles and reduce environmental problems caused by the use of emulsifiers.

Synthesis and characterization of fluoro-silicone polyacrylate latex emulsified with novel green surfactants

The novel fluoro-silicone polyacrylate latex was successfully synthesized in the presence of a novel green mixed emulsifier of β-cyclodextrin ( β-CD) and sodium lauroyl glutamate (SLG) by semi-continuous seeded emulsion polymerization, which was initiated with potassium persulphate. Methyl methacrylate (MMA) and butyl acrylate (BA) were used as the main monomers, while hexafluorobutyl methacrylate (HFMA) and vinyltriethoxysilane (VTES) were used as the functional monomers. The resultant latex and its film were characterized by Fourier transform infrared spectroscopy, thermogravimetric analysis, differential scanning calorimetry and contact angle determinator, respectively. The optimum conditions of preparing the fluoro-silicone polyacrylate latex are as follows: the amount of compound emulsifiers are 7.0%; β-CD: SLG = 1:2; the amount of initiator is 0.7%; the appropriate proportion of main monomer of MMA: BA = 1:1; and the amounts of HFMA and VTES are 6.0% and 4.0%, respectively. In this case, the resultant latex has high conversion rate, low gel rate and good stability. Results showed that both thermal stability and hydrophobic property of the latex are improved with the incorporation of a small amount of HFMA and VTES.

Preparation of β-CD-HAP Composite Microspheres

β-cyclodextin-hydroxyapatite (β-CD-HAP) composite microspheres were prepared in invert microemulsion method using spherical morphology hydroxyapatite nanoparticles (nHAP) as raw materials, Span-Tween cosurfactant as mixed emulsifier and epichlorohydrin as cross linker agent. The structure, morphology and β-CD-HAP was characterized by Fourier transform Infrared spectroscope (FT-IR), X-ray powder diffraction (XRD), transmission electron microscope (SEM). Results showed that the β-CD-HAP microspheres were synthesized by adding epichlorohydrin, span-80, tween-80, and sodium hydroxide and the particle size of β-CD-HAP composite microsphere with good dispersion was several tens of nanometer.

Research on the Stability of the Paste-Like Silicone Impregnant

The protecting of concrete, which consists of coating a chemical substance onto concrete’s surface, has been applied to architectural conservation. There is increasing interest in studying materials for concrete which can reduce the infiltration of water and salt solutions and rehabilitate and extend its service life. Silicon compounds are frequently used as a base for commercial protecting paint due to their hydrophobicity and penetrability. However, the stability of the impregnant emulsion is affected by many factors. The effect of three main factors such as component, pH, and emulsifier were studied in this paper. The stability of the impregnant decreased with the increase of pH. And the mixed emulsifier and 4～6% amount of emulsifier would be optical for the stability of the system and maintain the activity at the same time.

Long-term stability investigation of o/w cosmetic creams stabilized by mixed emulsifier

Polyglyceryl-3 Methylglucose Distearate (PMD, TEGO? Care 450, Evonik, Germany)is natural (vegetable), non-ionic, PEG-free emulsifier, suitable for the formulation of oil-in-water (o/w) cosmetic creams and lotions. The oil phase components can be selected from mineral oils, vegetable oils and synthetic esters, which enable different variety of application profile of these emulsions. It is possible to prepare stable emulsions using low-level concentration of the PMD (2-3%) if lotions contain 10-25%, and creams 20-40 % of oil phase. PMD forms liquid crystal structure in the presence of stearic acid, glyceryl stearate, fatty alcohols, or their combinations. The o/w type creams, stabilized by these mixed emulsifiers are complex, multiphase systems. The aim of this work was to formulate, prepare and investigate long-term stability of the o/w creams stabilized by mixed emulsifier polyglyceryl-3 methylglucose distearate/glyceryl stearate/stearyl alcohol, depending on concentration levels of PMD (2% or 3%) and oil:water phase ratio (20:80 and 30:70). The samples were prepared using hot/hot procedure. Organoleptic inspection, centrifugation test, rheological measurements, electric conductivity and pH value measurements were performed 72 h, 1, 3, 12 and 30 months after preparation. The prepared samples were apparently white and homogenous creams. The consistency and homogeneity were preserved after centrifugation of the creams after 72 h, 1, 3, 12 and 30 months storage, and no phase separation could be detected. The pH values obtained are suitable for skin application. Conductivity values (25.2-63.7 ?S cm1, 72 h after preparation) were attributed to the multiple phase o/w emulsions with high percentages of fixed water. Results of the rheological measurements have shown that the investigated creams exhibited non-Newtonian thyxotropic behavior. The concentration of emulsifier PMD and oil phase content had an influence on the rheological parameters of investigated samples. The creams prepared with higher content of emulsifiers (3%) and oil phase (30%) exhibited higher values of apparent viscosities and thyxotropic area. The observed decrease of electrical conductivity and increase of apparent viscosities values, which occurred in the creams during 3 months of storage, were probably attributed to bulk water content decreasing. These changes are mildly expressed in the samples with higher content of oil phase. The obtained results of organoleptic characteristics, pH, electric conductivity value and rheological parameters during 30 months of storage indicate good long-term stability of the o/w creams prepared with mixed emulsifier containing PMD at low concentration levels (2% or 3%). Changes during ageing, caused by structuration of creams were less expressed in samples with 30% of oil phase, however, the observed differences were not related with the PMD concentration. In this case, advantage could be given to o/w cream prepared with 30% of oil phase, stabilized by using 2% emulsifier polyglyceryl-3 methylglucose distearate.

Synthesis of Superabsorbent Polymer in Inverse Emulsion via Post-Cross-Linking

Firstly a graft copolymer was synthesized by graft copolymerization of starch with acrylamide (AM) in inverse emulsion, and then the copolymer was deaminated and post-cross-linked by heating to produce three-dimensional superabsorbent polymer. The effect of initiate conditions, composition and concentration of emulsifier, cross-linking methods and conditions were investigated. The results show that the optimized conditions are as follows: The mixture of (NH4)2S2O8-(NH2)2CO are used as initiators, and molar ratio of initiators and acrylamide is 1.4∶105; The mixture of Span20 and Tween80 with the mass ratio of mSpan20∶mTween80=80∶20 is used as emulsifier, and the total mass fraction of the mixed emulsifier is 7% of the oil phase; Post-cross-linking method is used, and the conditions are Tc=130 °C – 140 °C, t=30 min. The water-absorbing capacity of superabsorbent polymer obtained under such conditions can reach up to 1300 – 1400 g/g in distilled water and 400 -500 g/g in saline, respectively. Its water retention rate can reach more than 90%.