Preparation and comparative evaluation of well-defined fluorinated acrylic copolymer latex and solution for ancient stone protection

In this work the well-defined fluorinated acrylic copolymer latex and solution were prepared by the radical initiated seed emulsion polymerization and solution polymerization, respectively, using the same monomers of dodecafluoroheptyl methacrylate (DFHM), butyl acrylate (BA) and methyl methylacrylate (MMA). The copolymer latex BA/MMA/DFHM was designed as core–shell structure and the copolymer solution poly(BA–MMA–DFHM) was structured with low molecular weight. The chemical and morphology structures as well as the film properties obtained from latex and solution were analyzed and compared by spectroscopic techniques (FT-IR and NMR), transmission electron microscopy (TEM), differential scanning calorimetry (DSC), gel permeation chromatography (GPC), scanning electron microscopy coupled with energy-dispersive X-ray detector (SEM–EDX) and static contact angles (CAs) instrument. Moreover, the BA/MMA/DFHM latex and poly(BA–MMA–DFHM) solution (with 29 wt% of DFHM) were applied onto two kinds of sandstone samples by capillary absorption, and their preliminary protecting efficiency was evaluated. It is demonstrated that the comprehensive performances of BA/MMA/DFHM latex films were quite comparable to those of poly(BA–MMA–DFHM) solution cast films, the latter exhibited a better protective performance.     

Preparation and characterization of novel self cross‐linking fluorinated acrylic latex

Self crosslinking fluorinated acrylic latex (SCLFAL) has been successfully prepared via starved seeded semibatch emulsion polymerization of butyl acrylate (BA), methyl methacrylate (MMA), 2‐(perfluoro‐(1,1‐bisisopropyl)‐2‐propenyl)oxyethyl methacrylate (POMA), and N‐methylolacrylamide (NMA). The resultant SCLFAL is characterized by Fourier transform infrared (FTIR) spectrometry and nuclear magnetic resonance (NMR). Influences of the added amount of NMA on the crosslinking degree, contact angle, particle size, and glass transition temperature (T_g) of the film are investigated. Results show that the crosslinking degree, contact angle, and T_g of the film can be improved when the moderate amount of NMA is introduced into the mixed monomers. However, the added amount of NMA has no marked effect on the particle size of SCLFAL. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Preparation of acrylic copolymer latex modified by fluorine,silicon, and epoxy resin

A series of modified acrylic copolymer latices have been prepared through a semicontinuous emulsion copolymerization process with a variety of hydrocarbon monomers and (perfluoroalkyl) methyl methacrylate, vinyltriethoxysilicone, and phenol‐formaldehyde epoxy resin. The composition of copolymer was analyzed by fluoride ion selective electrode analysis, ¹⁹F NMR, FTIR, crosslinking degree determination, and epoxy‐acetone method. The results showed that the fluorine monomer, silicon monomer and epoxy resin had copolymerized with acrylic monomers. The optimum mass ratio between the curing agent TEA and epoxy resin was 1.36 : 6. The determination results of stabilities (electrolyte stability, freeze‐thaw stability, high temperature stability and mechanical stability) of latices showed that the incorporation of fluorine monomer and silicon monomer improved freeze‐thaw stability and mechanical stability, whereas the epoxy resin did not have obvious effect on the stabilities. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

氟-硅-醋-丙共聚物制备及其在石质文物保护中的应用

丙烯酸酯树脂是一种常用的文物保护材料,但纯丙树脂的成本较高;醋酸乙烯酯(VAc)价格低廉且具有较佳的耐候性,故以部分VAc代替MMA(甲基丙烯酸甲酯),同时引入纳米SiO_2和TFEMA(甲基丙烯酸三氟乙酯),制备了不同纳米SiO_2掺量的氟-硅-醋-丙共聚物。研究结果表明:当w(纳米SiO_2)=3%(相对于单体总质量而言)时,氟-硅-醋-丙共聚物的综合性能相对最好;以氟-硅-醋-丙共聚物作为石质文物的封护材料,则封护石质样品与未封护石质样品相比,经人工老化试验后,前者的憎水性、耐老化性等均明显优于后者,说明氟-硅-醋-丙共聚物对石质文物的保护效果较好。     

Comparative evaluation of fluorinated and unfluorinated acrylic copolymers as water‐repellent coating materials for stone

An investigation on the influence of side‐chain fluorination on the performance of a series of acrylic‐based copolymers as protective coating materials for stones has been carried out by comparing them with unfluorinated polymeric analogues. For this purpose, a series of copolymers of 1H,1H,2H,2H‐perfluorodecyl methacrylate (XFDM) and 2,2,2 trifluoroethyl methacrylate (TFEM) with unfluorinated vinyl ether or acrylic comonomers have been synthesized, as well as their not fluorinated analogues, and applied to limestone and marble substrates. A silicone‐type commercial product, widely employed in the protection of stones in buildings and other artifacts, has also been tested as a reference material. Their protection efficiencies were then comparatively evaluated in terms of surface properties, water permeability, and appearance. It is shown that the presence of fluorine always has, as expected, a positive influence on the protective action of the polymer, increasing the water repellency of the coated stone. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 76: 962–977, 2000     

New fluorinated acrylic polymers for improving weatherability of building stone materials

Acrylic polymers are widely used for their suitability to be shaped in different molecular structures. However, while very appropriate for many applications, these materials are characterized by a limited outdoor stability. In order to improve this last characteristic while maintaining the simple and flexible synthetic route, a study was performed based on the preparation of fluorinated polymers from acrylic monomers where several H-atoms in different positions were replaced with F-atoms. The structure design was aimed to optimize (e.g. minimize) the fluorine content of the final material while obtaining improved chemical and photochemical stability, good filmability and limited permeability to condensed water. The preparation of polymers of methacrylates derived from partially fluorinated alcohol by free radical mechanism is described. The fluorine content and distribution in the macromolecules is modulated by selecting different monomers and by copolymerization with nonfluorinated acrylates or vinylethers. The selection of the comonomers and their relative content in the polymer allows to control the glass transition temperature and the filmability as well as the protection efficiency of the coating. Polymers derived from more complex monomers such as -trifluoromethyl-methylacrylate are also described. The suitability of these new materials for protective coating of stones is tested by evaluating their stability to different chemical and physical agents and their selective permeability to water vapour vs. condensed water.     

水性含氟丙烯酸酯共聚物的疏水性研究

以脂肪醇聚氧乙烯醚/十二烷基硫酸钠/阴离子含氟乳化剂(AEO/SDS/FSA)为复合乳化剂体系,以甲基丙烯酸十二氟庚酯(FMA)、丙烯酸丁酯和甲基丙烯酸甲酯等原料合成了稳定的水性含氟丙烯酸酯共聚物(PFA)。考察了FSA用量对聚合反应稳定性的影响,并研究了FMA用量和FSA用量等因素对PFA疏水性的影响规律。     

In situ polymerization of unfluorinated and fluorinated acrylic copolymers for the conservation of stone

The effectiveness of butyl methacrylate/ethyl acrylate–based copolymers as consolidants for stone was investigated. The penetration of polymeric consolidating products is extremely slight because of their macromolecular nature and in situ polymerization of the monomers is suggested as an alternative technique to the use of macromolecular solutions. The efficiencies of three products synthesized in situ and fluorinated by various copolymers were comparatively evaluated in terms of surface properties, water permeability, and consolidation on a selected stone substrate. Moreover, because the environmental stability of such polymeric products is one of the key factors for their extensive application for conservative treatments, the photooxidative stability of reference polymers prepared in vitro was also investigated. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 91: 3202–3213, 2004     

Surface properties of polymethylenediamine-fixed styrene/acrylic acid copolymer latex

Surface charge density, ζ-potential, and dispersion stability of polymethylenediamine (PMD)-fixed styrene/acrylic acid copolymer [P(St/AA)] latex were investigated. PMD-fixed P(St/AA) latices are amphoteric and have isoelectric points at pH 4–7. Though the flocculations were observed at neutral pH, the pHs where the flocculation rates were maximum are slightly higher than were the isoelectric points. This result suggests the influence of the expansion of PMD-fixed polymer layer surrounding the particles on the flocculation. The fixation of PMD to the surface of P(St/AA) latex lowers the dispersion stability for high electrolyte concentration.     

环氧乳液与含氟乳液的拼混研究

运用种子乳液聚合法制备了固含量(固体质量分数)为45%的含氟乳液;运用后乳化法制得了环氧乳液。ATR-FTIR测试表明环氧乳液与含氟乳液进行了有效的拼混。运用KrussK12型动态表面能分析仪测试了含氟涂膜对水和十六烷的接触角,对影响拼混乳液涂膜性能的因素如环氧树脂及其固化剂的比例、氟原子含量、成膜基材材质、成膜温度等进行了探讨研究。结果表明制备的含氟拼混乳液性能良好。     

聚含氟丙烯酸酯/聚氨酯共聚物细乳液的制备及表征

以甲苯二异氰酸酯(TDI)和甲基丙烯酸羟乙酯(HEMA)为原料,合成了丙烯酸酯/聚氨酯(PUA)预聚体;采用细乳液聚合法,合成了聚含氟PUA细乳液。使用红外光谱(FT-IR)和核磁共振(1H-NMR)表征了PUA预聚体及共聚物的结构组成,用激光光散射粒度仪(PCS)分析了乳胶粒的粒径及其分布,并考察了氟单体用量对乳胶膜的吸水率和表面性能的影响。研究结果表明,乳胶粒的粒径随着PUA预聚体用量的增加而增大;当氟单体质量分数由0增至20%时,乳胶膜的吸水率由10.3%降至4.2%,表面自由能由34.89mJ/m2降至15.66mJ/m2,说明氟单体的加入较好地改善了乳胶膜的表面性能。     

高羟基含氟丙烯酸乳液的合成及性能研究

以丙烯酸酯类单体作为原料,以过硫酸钾为引发剂,采用预乳化半连续乳液聚合方式合成了高羟基丙烯酸乳液,并在后期补加氧化还原体系引发剂,提高了单体的转化速率。系统地研究了乳化剂用量、羟基单体、氟单体、硅单体含量等因素对涂膜性能的影响。最后,将制备的丙烯酸羟基组分同水性固化剂配制成双组分水性丙烯酸聚氨酯清漆,并分析清漆的性能。     

Preparation and reticulation of styrene acrylic/epoxy complex latex

The styrene acrylic/epoxy (SA/EP) complex latex with high content of epoxy resin was successfully prepared through emulsion polymerization initiated by both water-soluble and oil-soluble initiators. The resulting complex latex demonstrated regular spherical morphology with a diameter ranging 150–300 nm and with a narrow size distribution. The compatibility between epoxy and styrene acrylic improved due to the styrene acrylic grafting epoxy formation during grafting copolymerization. The factors influencing the structure and storage time of the complex latex were investigated and the corresponding mechanism was revealed. The SA/EP complex latex can form crosslinking structure with epoxy curing agent at room temperature. The crosslinked complex latex film shows good mechanical properties and excellent chemical resistance. These SA/EP complex latexes show great potential in developing high-performance aqueous paints and adhesive.     

Preparation of amphoteric latex by modification of styrene–acrylamide copolymer latex

Styrene–acrylamide copolymer latex prepared from the polymerization in an emulsifier-free aqueous medium was treated with hypochlorite and sodium hydroxide. The resulting latex indicated amphoteric property due to amino and carboxyl groups formed by the Hofmann reaction and competitive hydrolysis of amide groups, respectively. Amphoteric latices with the same particle size but different charge density (1.0–3.0 ionic groups/100 Ų) and different isoelectric points (6.4–9.2) have been prepared by changing the reaction conditions.     

Preparation and permeability of solutes through acrylic acid-g-methylcellulose copolymer membranes

Graft copolymer membranes from the methylcellulose and the acrylic acid were prepared and their properties and the permeability of four solutes were estimated. Acrylic acid-g-methylcellulose (AA-g-MC) copolymer dissolved in aqueous acetone solvent was cast to prepare membranes followed by the subsequent crosslinking either with aluminium potassium sulfate or by the thermal-curing method. The equilibrium water content in the membrane increased with the volume fraction of acetone in the aqueous acetone solvent system. Membrane, the ionically crosslinked with the aluminum potassium sulfate, showed the water content in the range of 38.5 and 58.4% and 0.25–0.33 kg/mm² of the tensile strength in the wet state. Compared with ionically crosslinked membranes, thermally dried membranes exhibited a more dense structure, resulting in lower water contents and higher mechanical strength. Experimental results on the permeation of four small and midsize solutes through the graft copolymer membranes revealed the molecular weight dependence of the permeability coefficient. The higher the degree of swelling, the greater the permeability coefficient. Ionically crosslinked membranes had higher solute permeability than the commercial Cuprophane membrane had. © 1993 John Wiley & Sons, Inc.     

丙烯酸共聚物改性PVP固体胶的研制

探讨了不同pH值下丙烯酸共聚物与聚乙烯吡咯烷酮（PVP）相溶性：考查了固体胶溶液黏度与聚乙烯吡咯烷酮浓度、硬脂酸钠浓度和丙烯酸共聚物浓度的关系：发现添加丙烯酸共聚物能降低固体胶溶液黏度,提高固体胶的生产效率和灌装效率。设计了丙烯酸共聚物改性PVP固体胶的配方和工艺,测试了固体胶的性能。     

微波辐射制备室温自交联含氟聚丙烯酸酯乳液

在微波辐射下,以甲基丙烯酸十二氟庚酯(DAAM)为含氟单体,双丙酮丙烯酰胺为功能单体,己二酸二酰肼为交联剂,阴离子十二烷基硫酸钠和非离子脂肪醇聚氧乙烯醚为复合乳化剂,在过硫酸钾的引发下,制备了可室温自交联的含氟聚丙烯酸酯乳液。考察了交联单体用量对转化率、粒径分布及分布指数和乳胶膜吸水率的影响。w(DAAM)为5%时,乳液乳胶粒呈球形,平均粒径在60~70 nm。随着DAAM用量的增加,乳胶膜吸水率减小,此时交联起主导作用;进一步增加DAAM用量,乳胶膜吸水率反而增大,此时亲水性起主导作用。     

苯乙烯-对氯甲基苯乙烯共聚物胶乳微球的制备及表征

以苯乙烯（St）和对氯甲基苯乙烯（VBC）为共聚单体,过硫酸钾（KPS）为引发剂,十二烷基苯磺酸钠（SDBS）为乳化剂,采用乳液聚合法制备了富含氯甲基的苯乙烯-对氯甲基苯乙烯共聚物功能微球。采用红外光谱（FT-IR）、扫描电镜（SEM）、激光粒度仪和X射线光电子能谱（XPS）对样品进行表征,研究了乳化剂用量、单体用量、引发剂用量、反应时间、反应温度等因素对微球粒径、乳液转化率的影响。结果表明,产物微球粒径均一,表面光滑、富含氯甲基功能基团,采用此方法可以制备粒径在100～250 nm的功能高分子微球。     

Preparation and evaluation of fluorinated hydrophobically associating polyacrylamide

A twin-tailed fluorinated macro-monomer AMPD was prepared by dodecylamine, POSF and acryloyl chloride. Then the hydrophobically associating copolymers (PFPAM) were prepared by micellar copolymerization of acrylamide (AM) and AMPS with AMPD in an aqueous solution. The structure and composition of PFPAM were characterized by FT-IR, ¹H-NMR, ¹⁹F-NMR and Tg. Macroscopic and microscopic self-assembly associative properties in solutions of PFPAM as well as the effects of salt on the associative behavior were studied via viscosimetry, SEM, surface tension and AFM. The results show that with the polymer concentration increase, the viscosity increased and the surface tension decreased, so as to the salt solution. The concentration corresponding to the onset of increase in the viscosity was close to the onset of decrease in the surface tension. That lead to the CAC values from viscosity measurements are mostly in accordance with the data obtained from surface tension measurements.