【作者】 高松华；

【导师】 闻立时； 雷明凯；

【作者基本信息】 中南大学 ， 凝聚态物理， 2008， 博士

【摘要】 采用射频容性耦合、感性耦合CF₄等离子体对硅橡胶试样进行表面改性。等离子体改性前后硅橡胶试样表面形貌、化学官能团和疏水疏油性分别由原子力显微镜（AFM）、衰减全反射- Fourier变换红外光谱（ATR-FTIR）、X射线光电子能谱（XPS）和静态接触角表征。当CF₄气体流量为20 sccm,经200 W射频容性耦合与200 W射频感性耦合等离子体处理5 min后,硅橡胶试样表面均方根粗糙度（R_q）由原始试样的42.460 nm分别增至134.425 nm和46.613 nm。说明在对硅橡胶试样处理过程中,由于载有试样的高频电极较高自偏压的存在,CF₄等离子体中阳离子经加速后轰击试样表面,增强了对硅橡胶试样表面的溅射、刻蚀作用,射频容性耦合CF₄等离子体在改变试样的微观形貌方面明显强于感性耦合等离子体处理工艺。通过衰减全反射-Fourier变换红外光谱（ATR-FTIR）分析可知:经容性耦合CF₄射频等离子体200 W直接处理20 min后,硅橡胶试样表面官能团Si-O-Si、-CH₃（存在于Si-CH₃）以及C-H（存在于-CH₃）与Si-（CH₃）₂的含量强度比,由原始试样的0.914、0.414、0.081,分别减至0.796、0.131、0.029;加Ar容性耦合等离子体100 W预处理5 min后,再经容性耦合CF₄射频等离子体200 W处理20 min,则分别为0.795,0.226,0.060。利用去卷积法分析X射线光电子能谱（XPS）得到:感性耦合CF₄射频等离子体处理后,硅橡胶试样表面出现碳氟官能团（C-F₂、C-CF_n和CF-CF_n）和硅氟结构（一[-SiFCH）3-O-SiFCH₃-]_n-、-[SiF₂-O-SiF₂-]_n-和-[-SiFCH₃-O-SiF₂-]_n-),并且随处理时间的增加,F-Si含量出现从小于到逐渐超过F-C含量的变化,引入的F元素含量最高可达20.05%（对应处理时间为10min）;而容性耦合CF₄射频等离子体处理后,试样表面出现的硅氟结构与感性耦合处理后相似,但只发现一种碳氟官能团（C-CF_n）,而且F-Si的含量一直大于F-C的含量,引入的F元素含量最高也只有14.01%（对应处理时间为20 min）。以上数据说明容性耦合CF₄等离子体处理过程中,CF₄等离子体中的阳离子通过高频自偏电场的加速后,对试样表面的轰击、溅射或刻蚀作用大大加强,在试样表面通过断键作用产生活性基点并形成硅氟结构的作用和对碳氟官能团的剥离作用强于感性耦合CF₄等离子体工艺。比较两种不同耦合方式CF₄射频等离子体改性硅橡胶试样,射频容性耦合等离子体改性硅橡胶试样表面双疏性能明显优于射频感性耦合工艺:在容性耦合CF₄等离子体200 W直接处理5 min的工艺条件下,得到最佳表面疏水疏油性能,对应静态接触角测量值从原始未改性试样的100.7°、61.6°分别提高到150.2°、123.6°。总之,虽然两种不同耦合方式CF₄射频等离子体处理工艺有所区别,但都是通过增加表面含氟非极性官能团含量和表面粗糙度两个因素,降低硅橡胶表面能,提高试样表面与水和油的静态接触角的大小（即表面双疏性能）。射频容性耦合CF₄等离子体对硅橡胶双疏改性效果优于射频感性耦合工艺,主要是由于载有试样的高频电极较高自偏压的存在,CF₄等离子体中阳离子经加速后轰击试样表面,增强了对硅橡胶试样表面的溅射、刻蚀和断键作用,同时满足了增加表面含氟非极性官能团含量和表面粗糙度两个提高表面双疏性能的因素,并且证实增加表面粗糙度对双疏性能的提高程度强于含氟官能团引入的贡献。更多还原

【Abstract】 Silicone rubber（SIR） samples are modified by CF₄ radio frequency（RF） capacitively coupled plasma（CCP） and inductively coupled plasma（ICP）, respectively.Surface morphology,functional groups,and hydrophobic and oleophobic properties of the CF₄ plasma modified SIR samples are characterized by using atomic force microscopy（AFM）,attenuated total reflectance Fourier transform infrared（ATR-FTIR） spectroscopy,X-ray photoelectron spectroscopy（XPS） and static contact angle（SCA） measurement.Surface root-mean-square（RMS） roughness（R_q） of the SIR samples, which were modified by CF₄ RE CCP and ICP at power of 200 W and gas flux of 20 sccm for treatment of 5 min,respectively,increases from 42.460 nm for original surface to 134.425 and 46.613 nm.It is concluded that the amendment in surface morphology by CF₄ CCP process is better than that by CF₄ ICP process because the positive ions of CF₄ CCP have more kinetic energy than CF4 ICP to ablate or etch the SIR samples’ surfaces owing to the higher self-bias existing in the sample holder.The peak ratios of Si-O-Si/Si-（CH₃）₂,-CH₃/Si-（CH₃）₂,and C-H/Si-（CH₃）₂ in ATR-FTIR spectra of SIR samples modified by CF₄ CCP at RE power of 200 W for 20 min treatment decrease from 0.914,0.414,and 0.081 for original surface to 0.796,0.131,and 0.029,respectively;And if the samples are treated by Ar CCP at RE power of 100 W for 5 min treatment before the same treatment of CF₄ CCP,those peak ratios decrease to 0.795,0.226,and 0.060. XPS were analyzed by deconvolution method and some conclusions are listed as follows:there are fluorocarbon groups such as C-F₂,C-CF_n,and CF-CF_n, and fluosilicic structures such as -[-SiFCH₃-O-SiFCH₃-]_n-,-[-SiF₂-O-SiF₂-]_n-, and -[-SiFCH₃-O- SiF₂-]_n- on the surfaces of SIR samples modified by CF₄ ICP,and the percentage concentration of F-Si increases and gradually preponderates over that of F-C with the increase of treatment time,moreover, the maximum of F content reaches 20.05%at the treatment time of 10 min. Compared CF₄ CCP process with CF₄ ICP process,although there are similar fluosilicic structures on the surfaces of SIR sample modified by the two types of processes,there is only one type of fluorocarbon groups----C-CF_n discovered on the modified surfaces.In addition,the percentage concentration of F-Si is always exceeding in that of F-C,and the maximum of F content is only 14.01%at 20 min treatment.According to the data above,it is concluded that the treatment process of CF₄ CCP overruns that of CF₄ ICP in the ablation of fluorocarbon groups and formation of fluosilicic structures.CF₄ CCP treatment process predominates over CF₄ ICP treatment process in improving the hydrophobic and oleophobic properties of SIR surfaces.The static contact angle for H₂O and CH₂I₂ were improved from 100.7°and 61.6°for original sample to 150.2°and 123.6°under the condition of optimal technological parameter which is CF₄ CCP at RF power of 200 W for 5 min treatment.In conclusion,although there are differences in treatment process between the two types of CF₄ coupled plasmas,the decrease of surface energy and increase of the static contact angle for H₂O and CH₂I₂ are both decided by increasing the fluoric groups and surface roughness according to the two types of processes.The main reason,for which the modified effects of hydrophobic and oleophobic properties of CF₄ RF CCP are better than that of CF₄ RF ICP, lies in self-bias existing in the sample holder so that the positive ions of CF₄ plasma can be accelerated and acquire higher kinetic energy to bombard,to ablate,and to etch the samples’ surfaces,meanwhile,meet the need to increase the fluoric groups and surface roughness which influence the hydrophobic and oleophobic properties of SIR samples.Moreover,it is proved that the degree of hydrophobic and oleophobic properties improved through the increase of surface roughness is better than that through the introduction of fluoric groups.更多还原