Synthesis and surface properties of fluorinated block copolymers containing sulfonic groups

A series of fluorinated block copolymers with different fluorinated block lengths and compositions were synthesized by atom transfer radical polymerization (ATRP), and then the block copolymers containing sulfonic groups with various sulfonation levels were successfully prepared further via a sulfonation reaction. These well‐defined block copolymers were characterized by means of Fourier transform infrared (FTIR), ¹H‐nuclear magnetic resonance (NMR) and gel permeation chromatography (GPC). The surface activities of the fluorinated block copolymers containing sulfonic groups in N‐methyl pyrrolidone solution and the surface properties of the films prepared from such a solution were examined, and the experimental results showed that the fluorinated block copolymers exhibited a high surface activity in solution and quite a low solid surface energy of films, even though they contain hydrophilic sulfonic groups. The critical surface tensions of these copolymers were estimated and were comparable to that of polytetrafluoroethylene. Even more interestingly, the surface activities of the block copolymers containing sulfonic groups or sodium sulfonate groups in aqueous solution were also measured. It was found that the surface activity in aqueous solution was weaker than that in N‐methyl pyrrolidone solution and depended on both the length of the fluorinated block and the sulfonation level of the block copolymers. The surface properties of the films prepared from the block copolymers in aqueous solution were tested, and most of these films exhibited a hydrophilic surface property. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 4809–4819, 2004     

PREPARATION AND SURFACE PROPERTIES OF ACRYLIC COPOLYMERS CONTAINING FLUORINATED MONOMERS

A series of copolymers comprising butylmethacrylate, styrene, butylacrylate, hydroxypropyl acrylate and perfluoroalkyl methacrylate were synthesized by the free radical polymerization using BPO as an initiator. The surface property of the copolymer films was subsequently characterized. The contact angle measurements and energy dispersive analysis of X-ray （EDAX） show that the length and content of perfluoroalkyl side chains in the copolymers are crucial for the preparation of the film with low surface energy. At a given content of fluorinated monomers in the copolymers, the longer the perfluoroalkyl side chain, the larger the water contact angle of the copolymer films will be. On the other hand, the higher the content of fluorinated monomers, the lower the surface energy is. The water contact angle increases with the increase of the fluorinated monomer content and reaches a plateau at 3 wt% of fluorinated monomer content.     

Control through monomer placement of surface properties and morphology of fluoromethacrylate copolymers

The arrangement of monomers and morphology of fluorinated copolymers of methyl methacrylate (MMA) were found to be important for controlling the surface energy of the materials when formed into thin films. Novel copolymers of MMA and 2,2,3,3,4,4,4‐heptafluorobutyl methacrylate (F3MA) were prepared with different monomer placement, namely statistical and block arrangements of the monomer units. The surface energies decreased with increasing incorporation of F3MA, in a manner consistent with previous reports for similar copolymers; however, the surface energies of the block copolymers were consistently lower than the statistical copolymers. This was interpreted as arising from conformational restriction of presentation of the fluoromonomers to the surface in the statistical copolymers, and formation of phase‐separated domains at the surface of the block copolymers. The morphology of the block copolymers was confirmed by small angle X‐ray scattering measurements, which allowed calculation of a solubility parameter for the fluorinated segments. The results have implications for the design of more environmentally acceptable materials with ultra‐low surface energies. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 2633–2641     

Preparation and Surface Properties of Fluorine‐Containing Diblock Copolymers PLMA‐Block‐PFAEA

A series of fluorine‐containing diblock copolymers based on lauryl methacrylate and 1H,1H,2H,2H‐perfluoroalkyl acrylate have been prepared by atom transfer radical polymerization (ATRP). The preparation process of PLMA‐Br macroinitiators was controlled within a reasonable time corresponding to the ln [M₀]/[M_t]～time plot of the reaction. FTIR, ¹H‐NMR, GPC and fluorine‐element analysis (FEA) were used to characterize the synthesized block copolymers. The solid surface activity of these polymers was demonstrated by contact angle measurement. The polymer films prepared by block copolymers with more than three fluorinated units showed low dispersion force contributions to the surface energy indicating the presence of the fluorinated block at the surface. The surface activity in solutions was measured by drop‐weight method. Ii is interesting to find, when the fluorine weight percentage is controlled constant, that PLMA‐b‐PFAEA with larger molecular size is more prominent in exploiting the fluorinated structure to reduce the surface tension of solutions. The block copolymer's ability in reducing surface tension of solutions also depends on the type of solvent.     

含羧基的含氟嵌段共聚物的合成及表面性能研究

利用原子转移自由基聚合反应以及随后的大分子链中叔丁酯基团的水解反应,合成了一系列具有不同含氟量和羧基含量的二嵌段共聚物,并分别通过GPC, ¹H NMR和FT-IR对共聚物的组成和结构进行了表征.进一步考察了这些含羧基或羧酸钠基团的含氟嵌段共聚物在吡咯烷酮或水中的溶解性能、临界胶束浓度、表面活性、达到饱和吸附时每个分子在表面所占据的面积,以及成膜后的临界表面张力等性能.实验结果表明,此含氟嵌段共聚物能显著降低吡咯烷酮和水的表面张力,成膜后表现出与聚四氟乙烯极为接近的低表面能特性.     

采用XPS与接触角法研究氟聚合物表面结构与性能

本文采用接触角和变角XPS方法对FA共聚物的表面能、 表面微相结构做了进一步的研究.     

Self‐emulsification and surface modification effect of fluorinated amphiphilic acrylate graft copolymers

We report on self‐emulsification and surface modification effect of novel fluorinated amphiphilic graft copolymers prepared with perfluoroalkyl acrylate and 2‐dimethylaminoethyl methacrylate using simple macromonomer technique and radical copolymerization. The interfacial properties of amphiphilic graft copolymers were characterized with light scattering, contact angle measurement, and X‐ray photoelectron spectroscopy. The preparation of fluorinated amphiphilic graft copolymer was verified using nuclear magnetic resonance and Fourier transform infrared spectroscopy. It was observed that the fluorinated amphiphilic graft copolymer has both strong hydrophobic and hydrophilic properties and shows self‐emulsification ability without addition of external surfactants. The graft copolymer shows very low surface energy even though the copolymer has low content of hydrophobic segment and better performance than random copolymer for low‐energy surface modification. The addition of small amount of the graft copolymer (0.1 wt %) into the base poly(methyl methacrylate) was sufficient to lower the surface energy less than that of poly(tetrafluoroethylene). © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010     

Synthesis and characterization of a new fluorinated macroinitiator and its diblock copolymer by AGET ATRP

A new fluorinated macroinitiator of poly 2,2,3,4,4,4-hexafluorobutyl methacrylate-Br (PHFMA-Br) was prepared via activator generated by electron transfer atom transfer radical polymerization (AGET ATRP), and then a series of fluorinated block copolymers with different fluorine content were successfully synthesized from the macroinitiator by the second step AGET ATRP. GPC, FTIR and ¹H NMR data obtained verified the synthesis. Contact angle measurement indicated that proper fluorine content could decrease the surface energy and increase the contact angle of the copolymer films. XPS characterization showed that the large difference in surface energy between the block and random copolymer film resulted from the difference of the fluorine content on the surface, although the fluorine content of the two copolymers in bulk was similar. The self-assembly behavior of the fluorinated block copolymer in selective solvents was evaluated by the TEM study, and the stable micelles with a core-shell structure were observed when the copolymer content was about 1 wt%.     

Polystyrene–Polyperfluorooctylethyl acrylate Diblock Copolymers: The Effect of Dilution of the Fluorinated Mesogenic Chains on Bulk and Surface Properties

Summary : Three smectic poly(styrene-b-perfluorooctylethyl acrylate) block copolymers (S-b-AF8) with different degrees of polymerization (n, m) of the relative blocks were synthesized by atom transfer radical polymerization (S, n = 25; AF8 m = 2, 6, 23). The mesophase structure and transition temperatures were investigated by DSC and WAXD. The block copolymer having the shortest fluorinated block was blended with a thermoplastic elastomer SEBS in different proportions, in order to look at the effect of a further dilution of the perfluorinated groups on non-wetting properties. Thin films of the block copolymers as well as the blends exhibited large contact angles with both water and n-hexadecane, which resulted in low solid surface tensions. XPS findings at different photoemission angles confirmed the effective surface segregation of the mesogenic chains of the fluorinated polymer block.     

Copolymer architecture effects on the morphology and surface performance of epoxy thermosets containing fluorinated block copolymers

The architecture effects on phases and surface enrichment behaviors of epoxy nanocomposites containing fluorinated block copolymers are investigated by the incorporation of two novel copolymers composed of poly (2, 2, 2‐trifluoroethyl methacrylate) (PTFEMA) and poly (ε‐caprolactone) (PCL), PCL‐b‐PTFEMA and PTFEMA‐b‐PCL‐b‐PTFEMA, with identical molecular weight and composition. These fluorinated copolymers in epoxy display distinguished self‐assembled structures, as evidenced by dynamic laser scattering and scanning electron microscopy measurements. Static contact angle detection suggests that the nanocomposites display an obvious improvement in surface water repellency and a reduction in surface free energy. The enhancement in surface hydrophobicity is attributed to the enrichment of PTFEMA blocks at the nanocomposite surface and to the formation of the specific surface morphology, as confirmed by atomic force microscopy. The different architectures of the two block copolymers give rise to differences in phase‐structures, and the ultimate surface performances of composites. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2014 , 52, 1037–1045     

成膜溶剂与氟化嵌段共聚物膜的表面富集行为

利用接触角、XPS、SFG、AFM等技术研究了环己酮、甲苯和三氟甲苯为成膜溶剂所得聚甲基丙烯酸甲酯-b-聚（甲基丙烯酸-2-全氟辛基乙酯）（PMMA—b—PFMA）嵌段共聚物膜的表面结构与性能．发现浇铸成膜时成膜溶剂对聚合物氟化组分向表面富集程度的影响相对较小,而旋涂成膜时溶剂的影响很大．不管以何种形式成膜,三氟甲苯溶剂最有利于氟化组分向表面富集,甲苯次之,环己酮最差．这一现象与溶剂的挥发速度无关．聚合物在溶液中的聚集结构、气／液界面结构是造成成膜方式对聚合物表面结构与性能产生巨大影响的主要原因．当聚合物在溶液中形成以PFMA为核、PMMA为冠的胶束结构时,在溶液固化过程中氟化组分向表面富集需要较长的时间,这时由于成膜方法直接影响溶液的固化速度,造成其对氟化组分向表面富集的程度影响很大．当聚合物在溶液中以单分子或松散聚集体存在,在溶液固化过程中氟化组分向表面富集的速度很快,这时成膜方法对氟化组分向表面富集的程度影响很小．以上结果无论对理论研究还是应用研究都具有重要意义．     

Synthesis,UV-curing behavior and surface properties of fluorine-containing vinyl ether polymers

Five fluorine-containing vinyl ether monomers were prepared by the reaction between 2-vinyloxy ethanol, a fluorinated alcohol and hexafluorobenzene in the presence of sodium hydride in dimethylformamide. Two representative properties of these monomers, UV-curing behavior initiated by a cationic photo-initiator PAG 201 and surface free energy of coating films, were investigated. Photo-polymerization proceeded both rapidly and completely with a high double-bond conversion （〉 90%） and a fast curing rate （maximum curing time 〈 21 s） for three monomers. The surface energies of the monomers and the resulting polymer films were then investigated. The minimum surface free energy of the UV-cured homopolymer films reaches 7.1 mJ/m2. X-ray photoelectron spectroscopy data show that the low surthce tension is influenced by fluorine content in the soft segments and fluorinated chains＇ migration to the surface. The five monomers exhibit low viscosity, low surface energy, good thermal stability and good photo-polymerization properties, which make them great candidates for UV coating and photoresist applications.     

Optimization of HDPE direct fluorination conditions by XPS studies

A fluorination reactor was designed and built in the laboratory. The optimal conditions of fluorination within the reactor were selected by X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) analysis of fluorinated surfaces of a film and a plaque of pure high-density polyethylene (HDPE). This reactor was used to post-mould fluorinate plaques and films of a range of mixtures of virgin and recycled HDPE with and without (re)introduction of additives. The ability to be fluorinated has shown no dependence on the composition virgin/recycled HDPE.Comparison of in-line and post-mould fluorinated samples showed that fluorine concentration profile in depth is thinner in the in-line fluorinated sample when compared with the post-mould fluorinated sample, though the fluorination degree in the extreme surface is larger in the in-line fluorinated sample. This is attributed to a migration of lower surface energy chain blocks towards the surface in the material at high temperatures, which is the case in the in-line fluorination, hindered in the post-mould fluorination where maximum temperature is below the melting point to keep the macroscopic shape. The additives played a minor role in the ability of the surface to be fluorinated.     

Surface active semifluorinated diblock copolymers prepared by group transfer polymerization

Diblock copolymers consisting of poly(methyl methacrylate) and poly(2-perfluorobutylethyl methacrylate) with narrow molecular weight distribution have been synthesized by group transfer polymerization. Different ratios of the PMMA block to the fluorinated block have been prepared. It was found that all polymers are surface active. Critical micelle concentrations are not dependent on the fluorinated block length. Critical surface tensions, extrapolated from Zisman plots and the dispersion force component of the surface energies extrapolated from Girifalco-Good-Fowkes-Young plots were decreasing with increasing length of the fluorinated block.     

The outermost atomic layer of thin films of fluorinated polymethacrylates

In this paper, we investigate the surface properties of a series of copolymers of perfluoroalkyl methacrylate (CH2 = C(CH3)COOCH2CnF(2n + 1), n = 1, 6, or 10) and methyl methacrylate (MMA) and of blends of perfluorooctyl-end-capped poly(methyl methacrylate) (PMMA) and pure PMMA. The introduction of perfluoroalkyl groups significantly lowers the polymer surface energy as determined by the acid-base approach. X-ray photoelectron spectroscopy (XPS) confirms a higher fluorine concentration in the surface region (the outer 3.8 nm) as compared to in the bulk. The fluorine density in the outermost atomic layer is quantitatively determined by low-energy ion scattering (LEIS). A linear relationship is found between the fluorine density in the outermost atomic layer and the surface energy of the partially fluorinated polymethacrylates, irrespective of the length of the perfluoroalkyl chain. This linearity confirms Langmuir's "principle of independent surface action". Deviation from this linear relationship exists for both highly and sparsely fluorinated polymethacrylates and can be ascribed to the local (surface) ordering of the fluorinated tails and MMA units, respectively. This study may offer one further step toward a deeper understanding of the correlations between macroscopic surface properties and microscopic surface chemical composition.     

New fluorinated thermoplastic elastomers. III. Novel method of synthesis and characterization of alternating fluorinated polyimide/fluorinated polyhybridsiloxane block copolymers via polycondensation

The synthesis of fluorinated polyimide/fluorinated polyhybridsiloxane (FPI–FPHSX) block copolymers was achieved through the polycondensation of α,ω‐dichlorosilane fluorinated polyimides and α,ω‐disilanol fluorinated polyhybridsiloxanes. Three FPI–FPHSX block copolymers with 41, 50, and 76 wt % polyimide were synthesized and characterized by the tuning of the number‐average molecular weight of the soft polyhybridsiloxane segments. The influence of the soft‐segment length on the behavior of the thermoplastic elastomer material was studied, including the surface tension and thermal properties. The thermomechanical properties of the FPI–FPHSX block copolymers were also examined. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 2237–2247, 2005     

Facile hydrophobic modification of hybrid poly(urethane-urea)methacrylate aqueous dispersions and films through blending with novel waterborne fluorinated acrylic copolymers

Aqueous dispersions of fluorinated particles (PBF) based on copolymers of butyl acrylate with 2-(perfluorononenyloxy)ethyl methacrylate (FNEMA), 2,2,3,3-tetrafluoropropyl acrylate, and 2,2,3,3,4,4,5,5-octafluoropentyl acrylate, respectively, were synthesized by emulsion polymerization in the presence of unfluorinated and fluorinated anionic surfactant binary mixtures. These fluorinated dispersions showed good to excellent colloidal stability, as determined by freeze–thaw, centrifugation, and critical coagulation concentration measurements. Blending of small amounts (1–10 wt.%) of PBF latex particles with a waterborne hybrid poly(urethane-urea)-methacrylate (PUUA) resulted in a series of slightly fluorinated modified PUUA with good film-forming properties and low surface energy. The precursor PUUA had been synthesized separately by simultaneous chain extension of a poly(ester-urethane)-diisocyanate with ethylenediamine and soapless free radical polymerization of methyl methacrylate swelling the resulting branched or slightly cross-linked poly(urethane-urea) self-dispersible ionomer particles. The results of dynamic light scattering and zeta potential measurements suggest that the merging of PUUA and PBF particles and either engulfing or interdiffusion of the incompatible macromolecular phases occurred to some extent already in the colloidal state. Highly hydrophobic films with surface energy as low as 17 mJ/m² were obtained upon the hybridization of PUUA with the FNEMA copolymer. Thermal annealing allowed minimizing the effects of fast surface dynamics, leading ultimately to water absorption, and promoting synergistic enhancement of the resulting hybrid film hardness, as required for coating applications.     

Preparation of an environmentally friendly antifouling degradable polyurethane coating material based on medium-length fluorinated diols

A novel medium-length fluorinated diols and poly(L-lactide) (PLLA) were synthesized via Michael addition reaction and ring-opening polymerization, respectively. Subsequently, Synthetic medium-length fluorinated diols and PLLA were combined to prepare new polyurethane composites with degradability and low surface energy. The compositional analysis and structural characterization of synthetic materials were characterized by using fourier transform infrared spectroscopy (FT-IR) and proton nuclear magnetic resonance spectra (¹HNMR). Thermogravimetric analysis(TGA) indicated that the introduction of medium-length fluorinated diols improved the thermal stability of the polyurethane. The biodegradation and low surface energy of the polyurethane were investigated by static hydrolysis experiment and water contact angle test. It was found that the degradation rate of the polyurethane increased as measurement time went on when the PLLA content was under 40%, and the water contact angle increased from 71.12° to 108.24° with the increase of fluorine content, which indicated that the degradable and low surface energy polyurethane has a potential as a coating material for a marine antifouling coating application.     

Preparation and surface properties of latexes with fluorine enriched in the shell by silicon monomer crosslinking

A series of core-shell acrylic copolymer latexes containing fluorine enriched in the shell have been prepared by emulsion polymerization of a variety of hydrocarbon monomers with (perfluoroalkyl)methyl methacrylate and vinyltriethoxysilicone. In the presence of a reactive anionic and a long chain anionic-nonionic emulsifier, the core-shell latexes were prepared and characterized by transmission electron microscopy (TEM) and tapping-mode atomic force microscopy (AFM). From AFM and contact angle measurements, it was observed that the resulting fluorine and silicon-containing acrylic copolymers with surface energy as low as 15.5 mN/m formed a dense and gradient film containing a surface layer with high a fluorine content, and that the fluorinated particles can be fixed on the surface due to the crosslinking reaction of multi-functional silicon monomer even though the fluorinated carbon number was not enough to crystallize.     

含磺酸基团的含氟嵌段共聚物的溶液性能及其应用

利用原子转移自由基聚合以及随后的磺化反应合成了一系列具有不同含氟量和磺化度的嵌段共聚物P(SSt b FNEMA) (PSSF) .通过溶液粘度和表面张力的测定 ,研究了该含氟嵌段共聚物独特的溶液行为 .实验结果表明 ,PSSF能显著降低N 甲基吡咯烷酮溶液的表面张力 .然而 ,与N 甲基吡咯烷酮溶液的表面性能不同 ,PSSF不能显著地降低水溶液的表面张力 ;当PSSF中和成钠盐后 ,水溶液的表面张力趋于一致 .进一步通过TEM、1 H NMR考察了PSSF在不同溶液中的形态 ,发现PSSF在水溶液中以核壳结构存在 ,而在N 甲基吡咯烷酮溶液中主要以胶束的形式存在 .初步考察了PSSF对聚氨酯脲 丙烯酸酯 (PUA)复合水分散液的改性效果 ,发现只需加入少量的PSSF ,就可使PUA膜的吸水率从原来的 10wt%下降到 4wt% .