Characterization and Particle Size Control of Acrylic ...

1 Smithers Information Ltd, 201565 Polymers from Renewable Resources, Vol. 6, No. 2, 2015 Characterization and Particle size Control of Acrylic Polymer Latex Prepared with Green SurfactantsCharacterization and Particle size Control of Acrylic Polymer Latex Prepared with Green SurfactantsLijun Chen, Zhongbin Bao, Zhengrong Fu and Wen LiSchool of Chemical Engineering, Zhejiang University of Technology, Hangzhou 310032, ChinaReceived: 17 October 2014, Accepted: 25 November 2014 SummARyThe application of green surfactants, which have low toxicity, excellent biodegradability in emulsion polymerization, has not been reported in the literature. In the present paper, alkyl polyglycosides (APG) and sodium alpha-olefin sulfonate (SAOS) were used as the nonionic emulsifier and anionic emulsifier, respectively to synthesize Acrylic polymer latex. The Acrylic polymer latex was prepared via semi-continuous seeded emulsion polymerization of butyl acrylate (BA) and methyl methacrylate (MMA) in water phase initiated with potassium persulfate (KPS) when nonylphenol ethoxylates (NPEOs) and sodium dodecyl-benzenesulfonate (SDBS) and are replaced with APG and SAOS, respectively.

2 Both APG and SAOS have low toxicity, excellent biodegradability and outstanding properties. The structure of the Acrylic polymer latex was confirmed with FTIR spectrum. Differential scanning calorimetry confirmed that the resultant latex is a kind of random copolymer. The unimodal distribution of Particle size also confirmed that the Acrylic polymer latex was prepared successfully. Factors, which have an influence on Particle size of the resultant latex, were studied in detail. The optimum recipe of preparing the Acrylic polymer latex with small Particle size was obtained. Keywords: Acrylic polymer latex; Semi-continuous seeded emulsion polymerization; Alkyl polyglycosides; Sodium alpha-olefin sulfonate INTRODuCTION Acrylic polymer latexes play an important role in many industrial processes, such as the production of synthetic rubber, surface coatings, adhesives, as additives in Corresponding author: Lijun Chen.

3 From Renewable Resources, Vol. 6, No. 2, 2015 Lijun Chen, Zhongbin Bao, Zhengrong Fu and Wen Lipaper, textiles and many other products. At present, emulsion polymerization of butyl acrylate (BA) and methyl methacrylate (MMA) is one of the most common methods for preparing Acrylic polymer latexes. Emulsion polymerization involves dispersion of a relatively water-insoluble monomer ( BA and MMA) in water at the reaction temperature, initiated the persulfate initiator solution with the aid of surfactants [1]. In the system of the emulsion polymerization, the anionic surfactant and non-ionic surfactant are often used as emulsifiers to stabilize the polymer latexes. Usually, SDBS and NPEOs are widely used in industrial emulsion polymerization. Furthermore, SDBS and NPEOs residue in the environment [2]. However, there is a demand for biodegradable surfactants in the production of polymer latexes from a social and environmental viewpoint.

4 In one of the major fields of application, surfactants with a more favorable ecological profile, which present low toxicity, excellent biodegradability, are becoming key ingredients for eco-friendly polymer latexes. Koukiotis et al. [3] synthesized high solids stable translucent nanolatexes of MMA/BA copolymers and MMA/BA/Veova-10 terpolymers by a modified semi-continuous microemulsion copolymerization. In their work, a combination of various green industrial anionic and non-ionic surfactants free of alkylphenol ethoxylates (APEO-free) at low concentrations was used as emulsifiers. Huang et al. [4] prepared a polyacrylate emulsion by pre-emulsified semi-continuous seeded emulsion polymerization methods. In their study, environmental friendly alcohol ethoxylates(AEO-9), sulfosuccinic acid alkyl polyoxyethylene monoester disodium salt (A-102) and sorbitan monooleate (Span 80) instead of traditional APEO were chosen as surfactants in polymerization.

5 Our research group also prepared polymer latexes emulsified with DSB and alkyl polyglycosides [5, 6]. However, the above studies are focused on the replacement of NPEOs. The study on the replacement of SDBS is neglected strongly. The aim of this study is that the application of green surfactants, which present low toxicity, excellent biodegradability in emulsion polymerization, has not been reported in open literatures. The novelty of the study is the Acrylic polymer latex is synthesized using alkyl polyglycosides (APG) and sodium alpha-olefin sulfonate (SAOS), as the nonionic emulsifier and anionic emulsifier, respectively. The synthetic route is given in Scheme 1. The emphasis is put in the present work on optimizing the recipe of preparing the Acrylic polymer latex with small Particle size and its Characterization . Scheme 1. Synthetic route of preparing Acrylic polymer latex with green surfactants67 Polymers from Renewable Resources, Vol.

6 6, No. 2, 2015 Characterization and Particle size Control of Acrylic Polymer Latex Prepared with Green SurfactantsEXPERImENTALM aterialsBA and MMA were obtained from Shanghai Chemical Reagents Supply Procurement of Five Chemical Plants (China) and were distilled under reduced pressure prior to polymerization. KPS was bought from the Second Chemical Reagent Factory in Yixin (China). The commercial APG such as C12/14-APG (APG1214) was purchased from Guangzhou Huiyuan Green Chemicals Limited (China). SAOS was a gift from Zhejiang Zanyu Technology Co. Ltd (China). Sodium bicarbonate (NaHCO3) was obtained from Shanghai Hongguang Chemicals (China). The water used in this experiment was distilled followed by of Acrylic Polymer Latex via Semi-continuous Seeded Emulsion PolymerizationThe Acrylic latex was prepared with semi-continuous seeded emulsion polymerization, which was carried out in a 250 ml four-neck flask equipped with reflux condenser, mechanical stirrer, dropping funnels and heated with the water bath.

7 The optimum recipe for preparing Acrylic polymer latex with small Particle size was shown in Table 1. First, NaHCO3, APG and SAOS were introduced into the reactor which contained g of de-ionized water and was heated with water bath at the constant temperature of 80 C under the condition of moderate agitation. Then 20% (wt%) KPS aqueous solution and 20% (wt%) the mixed monomers were dropped into the reactor within 15 min simultaneously, and the reaction maintained for another 15 min. At this time, the seeded latex was obtained. Then rest of mixed monomers and KPS aqueous solution was fed into the reactor containing seed latex under starved-feed addition through two dropping funnels simultaneously within h. When the mixed monomers and KPS aqueous solution were fed completely, the reaction temperature was kept at 90 C for another 30 min to raise the conversion of Table 1. Optimum recipe for preparing Acrylic polymer latex with small Particle sizeIngredients Amount/gIngredients Amount/gBA amount68 Polymers from Renewable Resources, Vol.

8 6, No. 2, 2015 Lijun Chen, Zhongbin Bao, Zhengrong Fu and Wen Limonomers. The latex was then cooled to about 40 C, and NH4OH (25 wt%) was added to adjust pH to about Finally, the mixture in the reactor was cooled and filtered. Thus, the Acrylic polymer latex was obtained. CharacterizationFourier transform infrared (FTIR) spectrometric analyzer (Thermo Nicolet AVATAR370, USA) was used to analyze the chemical structures of the latex films. The differential scanning calorimetry (DSC) (DSC Q100, USA) was applied to determine the glass transition temperature (Tg) of the film of the latex. The heating temperature was in the range from -40 to 100 C. The heat rate was 10 C/min. The Particle size of the latex was determined by Zetatrac dynamic light scattering detector (Microtrac Limited Corporation, USA) at 25 C. The power and the wavelength of the diode laser used in the dynamic light scattering measures were 3 mW and 780 nm, respectively.

9 The film of latex was obtained from coating the latex on the clean glass and drying for 2 h at 80 C in the bake oven. In the case, the water and un-reacted monomers were removed completely. RESuLTS AND DISCuSSIONFTIR of Latex FilmFigure 1 is FTIR of the latex film. In Figure 1, 2956 cm-1 and 2874 cm-1 are the characteristic stretching peaks of C-H (CH3, CH2); 1727 cm 1 is stretching vibration peak of C=O; 1450 cm 1 is distortion vibration of COO-; 1385 cm-1 is the flexural vibration absorption peak of -CH3; 1235 cm-1 is the characteristic absorption peak of -C-O-C in the esters; 1160 cm-1 is the stretching vibration absorption peak of C-O-C; 1065 cm-1 is the vibration absorption peak of C-O. 990 cm-1 and 962 cm-1 are the characteristic absorption peaks of the polymer of BA. 842 cm-1 is the stretching vibration absorption peak of C=O in the Acrylic group. The stretching vibration of C=C disappears within the range of 1500 cm-1 and 1700 cm-1. FTIR spectrum confirms that BA and MMA are copolymerized to form the Acrylic polymer Transition TemperatureDSC curve of the film of the latex is presented in Figure 2, which shows that Tg of the film is C, which is different from those of homopolymer of 69 Polymers from Renewable Resources, Vol.

10 6, No. 2, 2015 Characterization and Particle size Control of Acrylic Polymer Latex Prepared with Green SurfactantsBA (-54 C) and MMA (100 C), which also directly confirms that the Acrylic polymer latex has been prepared successfully. In addition, in Figure 2, it can be seen that the latex has just only one Tg, which shows that the latex is a kind of random copolymer and the consistency among the chain segments is fairly good [7]. Particle size of LatexParticle size and its distribution of polymer latex are shown in Figure 3. It is found that the Particle size of latex is unimodal distribution. The unimodal distribution of Particle size is due to the copolymerization of BA and MMA [8]. Otherwise, its distribution of polymer latex is bimodal. The bimodal distribution of Particle size is formed when some part of BA or MMA participates in self-polymerization. This also confirms that the Acrylic polymer latex has been prepared successfully.