Cryo‐preservation for the repeated use of a PDMS prepolymer

Leftover uncured polydimethylsiloxane (PDMS) polymer is generally discarded. In an effort to minimize this waste, we have developed a method for cryo‐preserving PDMS prepolymer involving a simple storage technique for the preservation and repeated use over 1 month. Aliquots of the uncured PDMS prepolymer were stored at ?20 or ?80°C, then conveniently and easily thawed at body temperature (37°C). Proposed cryo‐preservation was successfully evaluated using diverse biological and physical tests. This method of cryo‐preserving PDMS reduces both the material waste and labor of soft lithography process and may enable soft lithography to be environmentally friendly relative to previous methods. The method may be popularly accepted for application to a variety of common microdevice fabrication procedures. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40378.     

Preparation and characterization of polysiloxane‐acrylate latexes with MPS‐PDMS oligomer as macromonomer

The latexes of polysiloxane and acrylate with methacryloxypropyl trimethoxysilane (MPS)–polydimethylsiloxane (PDMS) oligomer as macromonomer and Gemini surfactant as coemulsifier were prepared by emulsion copolymerization and characterized by ¹H‐nmr, gel‐permeation chromatography (GPC), FTIR, x‐ray photoelectron spectroscopy (XPS), and atomic force microscopy (AFM). First, the oligomer of MPS‐PDMS (Si? O? Si chain length = 24) were synthesized by the hydrolysis of MPS and the ring‐opening polymerization of octamethyl tetracyclosiloxane (D₄), the ¹H‐NMR and FTIR spectra indicated that when the reaction time was prolonged to 2 h, more than 90% of ? Si (OCH₃)₃ groups were hydrolyzed; Then, the emulsion polymerization was performed with the oligomer as macromonomer and Gemini Surfactant as coemulsifier, the result of FTIR indicated that almost all the macromonomer had been exhausted because there was no C?C characteristic peaks in the spectrum. XPS investigation of the latexes showed that with the increase of siloxane content, more and more polysiloxane occupied the outer layer of the membrane, which agreed well with the conclusion of contact angle and AFM measurements. With Gemini surfactant as coemulsifier in the system, the PDMS content in the system could reach to 50%, which was far higher than the other reported value. © 2009 Wiley Periodicals, Inc. Journal of Applied Polymer Science, 2009     

Self‐diffusion measurements of organic molecules in PDMS and water in sodium alginate membranes

The self‐diffusion of some organic molecules in silicone rubber and of water and water–ethanol mixtures in sodium alginate membranes was investigated to obtain information on the transport behavior in these systems. The temperature dependence of self‐diffusion was examined by the pulsed field gradient NMR technique. The experimental data confirm the homogeneous amorphous nature of PDMS and the affinity of silicone rubber to apolar solvents. The interrelations between solvent and polymer structures of the sodium alginate membrane varying the temperature have been obtained using differential scanning calorimetric. The results have been compared with the trend of self‐diffusion coefficients, and structure modifications of the membranes have been evidenced. The overall results confirm the potentialities of the technique used in measuring transport parameter in polymeric membranes. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 1119–1128, 1999     

Investigation of the effects of NAA‐type zeolite on PDMS composites

The aim of this article was to investigate the effect of a NaA‐type zeolite on a polydimethylsiloxane (PDMS)–zeolite composite. The obtained results show that the introduction of a NaA‐type zeolite into polysiloxane matrices results in a change of the equilibrium degree of swelling (DSe) of composites in toluene, their hardness, and their thermal stability. With increase in the zeolite, the time required to achieve the DSe is reduced, DSe decreases, and hardness increases. A double effect of the zeolite concentration on the change of the composite characteristics was noted. At zeolite concentrations of up to 20%, there is a drastic change of the DSe and hardness with zeolite concentration, while this effect is considerably less pronounced at higher concentrations. The results obtained show that a NaA‐type zeolite plays the role of a reinforcing filler. A new mechanism of bonding the zeolite into the composite was suggested. According to this model, there is a possibility that bonds are established between the polymer and the zeolite via interaction of the π‐bond of terminal vinyl groups of PDMS with the Na cation of the zeolite. With increase in the zeolite concentration in the composite, the total number of established polymer–zeolite bonds increases, but the density of the interaction decreases. This explains the change in the characteristics of the composite with the change of zeolite concentration. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 1171–1176, 2000     

Light‐emitting polymers containing 2,3,4,5‐tetraphenylthiophenyl moiety and different pendent groups

By appropriate chemical reaction, different substituents can be selectively attached to the four phenyl rings present in 2,3,4,5‐tetraphenylthiophene (TP) to prepare monomers, namely 2,5‐bis(4‐bromophenyl)‐3,4‐diphenylthiophene (BTP), 2,5‐bis(4‐bromophenyl)‐3,4‐bis[4‐(nonan‐1‐one)phenyl] thiophene (BTP‐N2) and 2,5‐bis(4‐bromophenyl)‐3,4‐bis[4‐(2‐heptyl‐4‐phenylquinoline)phenyl]thiophene (BTP‐Qu2). Three light‐emitting polymers, PTP, PTP‐N2 and PTP‐Qu2, with the common TP backbone were prepared by zero‐valent nickel‐catalyzed polymerization of BTP, BTP‐N2 and BTP‐Qu2 monomers, respectively. The substituent on the 3,4‐phenyl rings of the TP framework has a profound effect on the polymer properties. Without any 3,4‐substituent, the rigid PTP polymer has low solubility in organic solvents. With the flexible nonanoyl substituent, the corresponding polymer, PTP‐N2, has improved solubility but low quantum efficiency (Φ_F) due to the carbonyl group which enhances intersystem crossing. With both flexible chain and bulky 4‐phenylquinoline (PQ) ring substituents, PTP‐Qu2 has good solubility and an enhanced Φ_F since the introduction of both flexible chain and bulky PQ ring substituents prevents close chain packing. All three polymers exhibit similar emission spectra despite the distinct difference in the absorption pattern of PTP‐Qu2 compared with those of PTP and PTP‐N2. In the case of PTP‐Qu2, there is energy transfer from the PQ pendent ring to the TP backbone and results in emission similar to PTP and PTP‐N2. The TP backbone common in all the three polymers is responsible for the emission from the corresponding excited states. The electrochemical properties of PTP‐Qu2 were also investigated. Copyright © 2005 Society of Chemical Industry     

乙醇/水及乙酸/水体系的渗透汽化分离

以乙醇/水及乙酸/水体系为研究对象,研究了渗透汽化过程中料液浓度、温度因素对分离效果的影响;结合乙醇、乙酸对聚二甲基硅氧烷(PDMS)膜的溶胀特性差别,分析并讨论了两者在渗透汽化过程中可能的分离机理. 研究表明,PDMS膜能够优先透醇,但乙酸分子的缔合物以及羧基与疏水PDMS膜高分子链的强相互作用降低了其在膜中的扩散速率,使低温时乙酸/水体系优先透水,只有当温度在60℃以上时才表现出优先透酸,且分离效果较差.     

响应面优化法在PDMS/PVDF膜制膜条件优化中的应用

用响应面优化法优化了乙烯基封端PDMS/PVDF渗透汽化透醇膜的制膜条件,研究了硅橡胶浓度、B/A质量比、交联温度和交联时间对膜性能的影响,拟合了分离因子、渗透通量与四因素之间的回归方程,并用方差分析法考察了四因素的主效应、二次效应以及相互作用效应对复合膜的分离因子与渗透通量的影响。研究发现,硅橡胶浓度对膜的分离因子与渗透通量的影响最为显著,交联时间对分离因子几乎没有影响。通过对回归方程的优化分析得知,在料液乙醇浓度为10%(wt),操作温度40℃条件下,当硅橡胶浓度为93%(wt),B/A质量比为0.08,交联温度为100℃,交联时间为13.83 h时,膜的综合分离性能达到最佳,此时分离因子与渗透通量预测值分别为9.47、77.57 g(m2 h)1,渗透侧乙醇浓度达到51.3%(wt)。回归方程的验证实验结果表明,回归方程的估计值与实验值较为吻合,可用于乙烯基封端的PDMS/PVDF复合膜的渗透汽化性能的预测与优化。     

Sorption and diffusion of volatile organic compounds in fluoroalkyl methacrylate‐grafted PDMS membrane

Pervaporation is known as an excellent method for the purification of contaminated water, the extraction of aroma compounds, etc., and has been widely studied. The prediction of permeation is important for treatment, extraction, and quantitative analysis. To predict permeation, a solution–diffusion mechanism is proposed. The octanol–water partition coefficient (Pow) has been generally used in expressing hydrophobicity. The hydrophobicity, Pow, is closely related to the solubility of organic compounds. Also, the molecular volume is closely related to the diffusion of organic compounds. In this study, we improved polydimethylsiloxane (PDMS) membranes by plasma grafting of fluoroalkyl methacrylates (FALMA) to enhance the affinity of PDMS to volatile organic compounds (VOCs). Furthermore, we investigated the pervaporation through the plasma‐grafted PDMS membrane and the PDMS membrane and the solution–diffusion mechanism of various VOCs. The permselectivity of tetrachloroethylene (PCE) and toluene determined by the sorption and the diffusion characteristics permeating in the membrane was high. Because the molecular volume of the VOCs is greated than that of water and the permeates quickly penetrate in rubbery membranes like PDMS, permselectivity was not affected by the diffussivity. Solubility significantly affected the permselectibity during pervaporation through a hydrophobic rubbery membrane. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 75: 773–783, 2000     

Effects of Light‐Induced Regularity on the Physical Properties of Multiphase Polymers

A method that combines UV irradiation and pausing was developed to manipulate the regularity and the length scales of the morphology generated by phase separation in full‐interpenetrating polymer networks of polystyrene and poly(methyl methacrylate). Upon increasing the pause time of photopolymerization and photo‐crosslink processes, the morphology gradually changes from hexagonal‐like packing to random structures. The width of the loss tan δ obtained for these phase‐separated materials changes with the morphological regularity, suggesting a potential technique for fabrication of mechanical bandgap materials.

     

PDMS渗透汽化膜分离水中有机物的研究进展

渗透汽化(PV)膜分离技术是一种新型膜分离技术,适用于分离恒沸点混合物、近沸点溶液、热敏感性混合物、有机-有机混合物以及水溶液中少量有机物。PV分离水溶液中有机物的工业应用还处于初步阶段,文中从硅橡胶渗透汽化优先透有机物膜的制备条件、工艺应用参数及膜寿命等方面进行综述。膜生产放大和膜寿命是影响该技术推广的重要因素,可以从膜制备和应用工艺方面进行改进。     

Design of a Rubbery Carboxymethyl Cellulose/Polyacrylic Acid Hydrogel via Visible‐Light‐Triggered Polymerization

Hydrogels, as soft and wet materials, have attracted great attention in the field of functional biomaterials. Most recently, the designed hydrogels, according to the energy dissipation principle, overcome the low mechanical strength, poor toughness, and limited recoverability of common hydrogels and show excellent mechanical properties. However, most of these novel designed hydrogels are lacking of instantaneous recovery and antifatigue properties. In this study, a mesoscopic inhomogeneous hydrogel consisting of carboxymethyl cellulose and polyacrylic acid is synthesized through a facile, one‐pot, visible‐light‐triggered polymerization. The prepared hydrogel can be stretched over 700% with fracture strength as high as 850 kPa, and shows a high elastic modulus (180 kPa). The microgel aggregated structure endows an efficient energy dissipation mechanism to the hydrogel. After the internal network structure stabilizing, the hydrogel exhibits a recovery time within 10 ms and over 92% resilience during impact and cyclic tensile tests, respectively. The hydrogel with such excellent mechanical properties can extend its application in biomaterial fields.

     

Synthesis of vinyl substitute poly(silphenylene‐siloxane) via silyl hydride‐dialkoxysilane process

The synthesis of vinyl‐substituted silphenylene‐siloxane polymer through B(C₆F₅)₃ catalyzed polycondensation of 1,4‐bis(dimethylsilyl)benzene and vinylmethyldimethoxysilane is described. ¹H‐NMR, ²⁹Si‐NMR, and UV spectroscopy indicate that the vinyl groups remain undamaged during the polycondensation reaction. No hydrosilylation side reaction is observed under the reaction conditions. The microstructure of the polymer is not perfectly alternating with a randomization of 20%. The temperature for 5% mass loss is 430°C in inert atmosphere and 417°C in oxidative atmosphere with a residue of 56% at 700°C. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Light‐weight polypropylene composites reinforced with whole chicken feathers

Light‐weight composites reinforced with whole chicken feathers have better flexural strength than composites reinforced with feather fibers (barbs) and nearly thrice higher tensile strength and seven times higher tensile modulus than composites reinforced with powdered chicken feather quill. Chicken feathers are not only inexpensive and abundantly available but also have unique properties such as low density and hollow centers that make them preferable as reinforcement materials, especially for light‐weight composites. However, the traditional methods of developing composites do not provide the flexibility of using feathers in their native form as reinforcement. So far, the components in feathers such as barbs or quills have been used separately and/or feathers have been mechanically processed to destroy their native form in order to use feathers as reinforcement in composites. A new method of making composites using nonwoven webs as matrix allows the incorporation of reinforcing materials in their native form such as whole chicken feathers to develop composites. This research shows that whole chicken feathers can be used as reinforcement in composites with better flexural, tensile, and acoustic properties than composites made from processed chicken feathers. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Visible Light‐Mediated Metal‐Free Synthesis of Vinyl Sulfones from Aryl Sulfinates

Visible light and eosin Y catalyze the synthesis of vinyl sulfones from aryl sulfinates and alkenes by a photoredox process. The reaction scope is broad in aryl sulfinates and alkenes and the general and simple procedure provides a metal‐free alternative for the synthesis of synthetically valuable vinyl sulfones.

     

UV‐Triggered Optical Response and Oxygen Scavenging Ability of a Water‐Soluble Poly(N,N‐dimethylacrylamide‐co‐2‐vinylbenzylanthraquinone) Copolymer

A vinyl‐modified anthraquinone (AQ) derivative (Vinyl‐AQ) is synthesized through a palladium‐mediated Suzuki coupling reaction between vinylphenylboronic acid and 2‐chloromethylanthraquinone and, subsequently, copolymerized with N,N‐dimethylacrylamide (DMAM) through free radical copolymerization in organic solvent. The chemical structure of the resulting water‐soluble copolymer, P(DMAM‐co‐AQ), is verified using techniques such as proton nuclear magnetic resonance, attenuated total reflection‐infrared spectroscopy, thermogravimetric analysis, and UV–vis spectroscopy. The evolution of the oxygen scavenging abilities of aqueous P(DMAM‐co‐AQ) solutions after UV irradiation is monitored as a function of UV irradiation time, concentration of AQ moieties, and pH. The copolymer is proved an effective UV‐triggered oxygen scavenger, leading to dissolved oxygen contents below 1 ppm for the optimized experimental conditions. This behavior is related with the appearance of novel chemical species with interesting optical properties, as suggested by the respective evolution of the UV–vis absorption and photoluminescence spectra after UV irradiation.     

PDMS企业级部署探讨

介绍了主流的三维工厂设计软件之一———PDMS的企业级部署,分析了高效完成PDMS的企业级部署,能够最大化发挥PDMS软件的优势,助力设计企业升级设计平台和提升设计效率。提出了对企业级部署工作的建议,供同行参考。