Two Organic Phase Suspension Polymerization for Novel Hypercrosslinked Resin Bead by Polycondensation of CMB

The suspension polymerization with two organic phases was adopted to prepare spherical hyper- crosslinked resin by self-polycondensation of 4,4＇-bis-（chloromethyl）- 1, 1＇-biphenyl （CMB）. The chemical structure,morphology and pore characteristics of the novel spherical resin were characterized with Fourier transform infrared spectroscopy （FTIR）, micrograph and Brunauer-Emmett-Teller （BET）. It is found that the suspension system and stirring speed impose a great influence upon the regularity and size distribution of hypercrosslinked beads. To prepare CMB resin beads with diameter of about 300 μm, the optimal condition is as follows： stirring speed 300 r·min^-1, and the volume ratio of the two organic phases （nitrobenzene/dimethyl silicon oil） 1 ： 5. After the self-polycondensation and sqccedent post-crosslinking of CMB monomer, the spherical adsorbent presents high spec~al surface area （1190 m^2· g^-1） and abundant pore~volume （0.714 cm^3· g^-1）, and could be potentially applied qn the adsorption of various organic molecules and synthesis of porous ion exchanger.     

离子液体聚合物CO_2吸附性能研究

为提高离子液体吸附CO_2的性能,通过自由基聚合制备了季铵盐类离子液体聚合物,采用两步种子溶胀法使该聚合物形成多孔结构,并通过扫描电子显微镜和差热-热重分析法对其形貌和热稳定性进行表征。研究了4种溶胀剂制备的多孔聚合物吸附CO_2的性能,试验结果表明:制备的多孔聚合物具有发达的微孔结构,孔径在0.4~0.8 nm内连续分布,且较集中于0.5~0.6 nm,达到38%以上;溶胀剂的种类对孔径分布及累计孔容有显著的影响,可归因于溶胀剂与聚合物的溶解度差异,采用混合溶胀剂得到的孔径分布更加均匀,而采用环乙烷溶胀剂得到的累计孔容明显减少;多孔聚合物的CO_2吸附量主要受累计孔容的影响,累计孔容相当的聚合物吸附CO_2的量也近似,在273 K、0.101 MPa条件下,约为1.1%。     

Gelchromatographie,die möglichkeiten verschiedener trennmaterialien

Organic and inorganic materials are applicable to gel chromatography. In this paper the widely used highly crosslinked Styragel serves as a standard to test the separating power of porous glasses, silica, and aluminum compounds. Very high molecular polymers require gels with large pore sizes as separating materials. For this purpose inorganic gels are especially suited because of their strong mechanical stability. Polymers of low molecular weight can be separated by organic and inorganic gels with roughly the same efficiency. For these polymers one can select the gel material according to its chemical inertness. Then a reasonably pure physical separation process is possible.     

Chemische Methoden zur Analyse von Netzwerken

The chemical investigation of the network structure of crosslinked polymers requires the defined splitting of the polymer chains by inequivocal reactions. From nature and amount of the reaction products conclusions can be drawn on the network structure. The present possibilities and limits of the chemical analysis of crosslinked polymers are discussed on some examples of crosslinking polyreactions and subsequent crosslinking of macromolecules.     

Synthesis and characterization of new injectable and degradable dextran-based hydrogels

Injectable and degradable hydrogels are very interesting networks for drug delivery and cell transplantation applications since they can be administered in the human body in a minimally invasive way. In most cases, the crosslinking reaction occurs by photopolymerisation or free radical polymerisation; however, the use of chemical initiators may promote cell death. In the current work, injectable and degradable dextran-based hydrogels were prepared without the use of initiators. Dextran, a natural glucose-containing polysaccharide, was oxidized with sodium periodate (dexOx) and the derivatives characterized by NMR and FTIR spectroscopy's as well as by colorimetric techniques. The oxidized derivatives were crosslinked with adipic acid dihydrazide (AAD), forming a gel within 2-4 min. The obtained hydrogels were characterized by their mechanical properties, swelling and degradation behavior under physiologic conditions. In addition, the hydrogel interior morphology as well as porous structure was evaluated by scanning electron microscopy (SEM) and mercury intrusion porosimetry (MIP). MIP analysis showed that dexOx hydrogels crosslinked with 10% of AAD were macroporous with pore sizes ranging from 0.32 to 0.08 μm. As expected, the average pore size increased during hydrogel degradation as confirmed by SEM and MIP studies.     

Styrene — divinylbenzene copolymers,IV. Porosity changes during chloromethylation

The change in the porosity of styrene-divinylbenzene (S-DVB) copolymers during the chloromethylation reaction was investigated using apparent densities and equilibrium swelling in toluene. Maximum porosity of S-DVB copolymers does not change appreciably with the chloromethylation reaction. Only a slight decrease in the maximum porosity was observed in rigid networks, probably due to the partial destruction of the pore structure. However, with the substitution by chloromethyl groups, the degree of swelling decreases, which results in an increase in the stability of the porous structure in chloromethylated copolymers.     

Synthese von bipolaren Ionenaustauscherharzen

Synthesis of Bipolar Ion Exchange Resins Syntheses of weakly acid/strongly basic and weakly acid/weakly basic bipolar ion exchange resins with varying acid and basic capacities via subsequent introduction of the exchange active groups in suitable crosslinked skeletal polymers are described. Methylacrylate-styrene-divinylbenzene polymers of varying composition which can be quantitatively chloromethylated and subsequently fully aminated (trimethylamine) and partially saponified in one process step were used as starting polymers for weakly acid/strongly basic resins. The reverse route saponification of the ester groups first, followed by chloromethylation of the aromatic parts of the matrix and animation turned out to the possible, if at all, only for bipolar resins of strongly predominant basic character. The capacity parameters can be controlled through the composition of the matrix. Polymethylacrylates crosslinked with divinylbenzene served as polymer basis of the weakly acid/weakly basic bipolar ion exchange resins. The functionalization was achieved by partial aminolysis with polyamines (dimethylaminopropylamine, ethylenediamine, diethylenetriamine) and saponification with lyes. The number of basic and acid groups which can be introduced is governed primarily by the conditions of the aminolysis. The capacity parameters are controllable within a broad range by the procedures.     

Graft polymerization of propylene sulfide on crosslinked polystyrene

Sulfur containing graft polymers that may be of interest as polymeric transfer agents were synthesized. Graft polymerization of propylene sulfide on crosslinked polystyrene beads was investigated; both crosslinked polystyrene and its chloromethylated derivative were grafted. Crosslinked polystyrene was metallated by BuLi–TMEDA and was used to initiate anionic graft polymerization of propylene sulfide. Graft polymers of high polypropylene sulfide content corresponding to 10 mmol s/g were obtained. The grafted polypropylene sulfide was evenly distributed across the bead cross section. No change in bead surface characteristics was observed. Grafting on chloromethylated polystyrene beads was achieved by reaction between the chloromethylene groups with sulfide groups of performed polypropylene sulfide, and with terminal sodium thiolate groups of living polypropylene sulfide.     

Modeling changes of fractal pore structures in coal pyrolysis

Coal pyrolysis processes are numerically investigated in mathematically produced coal pore models which simulate real coal pores in the parameters of the porosity and fractal dimension. The simulations include FG-DVC chemical reaction model, gas molecular diffusion in pores, energy conservation model and coal swelling model. Numerical results are verified by experimental results qualitatively, and they revealed that both the porosity and volatile contents of the parent coal can affect the fractal dimension of the final char pores after pyrolysis linearly. A formula to predict the fractal dimension of char pores from its parent coal properties is obtained by curve fitting in numerous results.     

Swelling of porous ethylvinylbenzene–divinylbenzene copolymers and the stability of the pore structure

A series of porous ethylvinylbenzene–divinylbenzene (EVB–DVB) copolymers with DVB contents ranging from 22.0 to 98.4% were prepared using various amounts of toluene as the inert diluent, and studies were made on the copolymers as to their swelling properties, the stability of their pore structure, and the relationship between swelling in nonsolvents and variations in their pore structure. The swelling experiments showed that the ethanol regains of the copolymers were closely related to the course of phase separation, and the increases in both the DVB content and the volume fraction of monomers in the organic phase resulted in enhanced capacity of the highly crosslinked copolymers to keep swelling in solvents having extremely small affinity for these copolymers. The variations in pore structure, sometimes quite considerable, for copolymers pretreated with different solvents were observed even at DVB content up to 98.4% and further studies showed that a consistent relationship existed between pore volume variation and volume swelling ratio in ethanol for toluene modified copolymers.     

Phosphazene cyclomatrix network polymers: Some aspects of the synthesis,characterization, and flame‐retardant mechanisms of polymer

Novel phosphazene cyclomatrix network polymers were synthesized via nucleophilic displacement of activated nitro groups of tri(4‐nitrophenoxy)tri(phenoxy)cyclotriphosphazene and hexa(p‐nitrophenoxy)cyclotriphosphazene with the hydroxyls of bisphenol A. Both the monomers and polymers were characterized by Fourier transform infrared (FTIR) and ¹H‐NMR spectroscopy, and their structures were identified. The thermal and flame‐retardant properties of the polymers were investigated with thermogravimetric analysis in air, pyrolysis, and combustion experiments. Both solid and gaseous degradation products were collected in a pyrolysis process and analyzed with FTIR spectroscopy, gas chromatography/mass spectrometry, and scanning electron microscopy. The results demonstrated that the cyclomatrix phosphazene polymer would have excellent thermal stability and flame‐retardant properties if it could form a crosslinked phosphorous oxynitride structure during pyrolysis or combustion. A flame‐retardant mechanism of “intumescent” was proposed to elucidate the pyrolysis and combustion process. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 95: 880–889, 2005     

Zur Adsorption von Dämpfen chlorierter C2-Kohlenwasserstoffe an Adsorberpolymeren und Aktivkohlen

Adsorption of Vapors of Chlorinated C₂-Hydrocarbons on Polymeric Adsorbents and Activated Carbons The adsorption (isotherms, kinetics, dynamics) of vapors of chlorinated ethanes and ethylenes from inert gas onto the novel crosslinked polymeric adsorbent Wofatit Y 77 was studied in comparison to traditional polymeric adsorbent Wofatit EP 61 and activated carbons B 23 and R 23 at 20°C. The crosslinked microporous polymeric adsorbent Wofatit Y 77 adsorbs the greatest amount. But the adsorption velocity is slightly lower than at activated carbons and the macroporous polymeric adsorbent Wofatit EP 61, respectively. The obtained steep adsorption breakthrough curves were evaluated according to the model of adsorption zone. Furthermore, the breakthrough curves were predicted from data of equilibrium and kinetics due to the equilibrium model and the model of film and pore diffusion by Rosen.     

氯甲氧基丁烷的制备及初步应用

用正丁醇、多聚甲醛及干燥的氯化氢气体为主要原料,合成氯甲基化试剂———氯甲氧基丁烷(CMB)。采用傅里叶变换红外光谱(FTIR)与核磁共振氢谱(1HNMR)对产物进行了表征。考察了溶剂用量、物料摩尔比、反应温度及反应时间对CMB收率的影响。获得的最佳反应条件为:溶剂1,2-二氯乙烷50 mL,n(正丁醇)∶n(多聚甲醛)=3∶2,温度为0～5℃,反应时间为7 h;在该条件下,氯甲氧基丁烷的收率可达92%。用制备的氯甲氧基丁烷氯甲基化交联度为10%的白球得到氯甲基化聚苯乙烯微球,并用佛尔哈德滴定法测得其中氯的质量分数为13%。     

一种新型常温微量氯气吸附剂热动力学研究

用一次等量浸渍法制备氯气吸附剂。在反应温度为常温、空速小于或等于1 000 h-1、进口氯气体积分数小于或等于400×10-6、出口氯气体积分数小于或等于0.1×10-6的条件下,吸附氯容量大于或等于11%。通过分析实验测得了热力学和动力学参数,结果表明,该吸附剂吸附氯气过程满足热力学的Fueundlich方程和动力学的Dubbin-Radushkevich方程,同时得出了有关吸附剂的反应机理。     

化学干法热解制备污泥吸附剂及其工艺优化

针对传统化学活化法制备污泥吸附剂存在的问题,提出了采用化学干法热解技术制备污泥吸附剂工艺;以氯化锌为活化剂,以碘吸附值为工艺评价指标,采用响应面分析法研究了干法热解技术制备污泥吸附剂的工艺条件,结果表明：在热解时间和热解温度之间存在交互作用,当热解温度增加的时候,热解时间可以适当缩短,获得了污泥吸附剂的最佳制备工艺条件。即：热解温度为389.40 ℃,热解时间为83.64 min,氯化锌含量为21.40%;进行比较研究后发现,与传统化学活化法相比,化学干法热解技术制备污泥吸附剂的热解温度较低,热解时间较短,在此条件下制备的污泥吸附剂的比表面积增加了20.13%;污泥吸附剂的分析结果表明污泥吸附剂以中孔吸附为主,BJH孔径分布较宽,最高峰在4.2 nm左右,SBET为135.74 m2/g。     

Styrene-divinylbenzene copolymers,V. Inhomogeneity in the structure and the average degree of swelling

The compositional inhomogeneity and the average degree of swelling of heterogeneous styrene-divinylbenzene (S-DVB) copolymers were investigated using two morphological features of porous copolymers. At a fixed volume fraction of a nonsolvating diluent, the extent of inhomogeneous crosslinking increases with increasing DVB concentration. In addition, the crosslinking density of less crosslinked regions of the network decreases as the DVB concentration increases. The experimental results can be explained by the microgel-model of the network formation. The average degree of volume swelling can be predicted from the composition of the starting monomer mixture and from the porosity of the final copolymer dried from water. Depending on these parameters, the changes in the value of v₂, the volume fraction of copolymer in the swollen gel, and the conditions for the pore stability are discussed.     

Synthesis and characterization of superabsorbent hydrogels composites based on polysuccinimide

A kind of novel superabsorbent hydrogel with high swelling ratio property that could be used for the development of water absorbing resin, soil water retention agent, and chemical sand‐fixing material was synthesized in this study. The hydrogels were prepared by the crosslinking reaction of polysuccinimide (PSI). The relationships between swelling ratio and volume of solvent as well as the concentration of crosslinking agent were investigated in detail. Several composites, such as starch, carrageenan, and polyacrylamide, were added into hydrogels to enhance the swelling ratio. It was found that the swelling ratio was significantly increased, which the maximum water absorbency was enhanced 2.46 times when the composite polyacrylamide (PAM) was added compared to the control. The effects of ionic strength and sensitivity of pH on hydrogels were also studied. The modified hydrogels products with swelling ratio less sensitivity to the salinity as well as relative high swelling ration in salinity system were also obtained by adding PAM. Through the Fourier transform infrared spectroscopy (FTIR) characterizations, the crosslinking reaction mechanism and the structure of composite were proposed. In addition, the transmission electron microscopy (TEM) examinations showed that some composite materials elevated the physical crosslinked and connected channels density substantially. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 550–557, 2006     

A novel injectable and in situ crosslinked hydrogel based on hyaluronic acid and α,β-polyaspartylhydrazide

A new injectable and in situ crosslinked hydrogel, based on a hyaluronic acid (HA) derivative and α,β-polyaspartylhydrazide (PAHy), was produced during the research. This biodegradable and high molecular weight hydrogel can be in situ crosslinked in 15 s by the condensation reaction between aldehyde and amine groups. The HA derivative carrying aldehyde (HAALD) was oxidized from HA by sodium periodate, while the synthesis of hydrogel was performed in a phosphate-buffered saline solution (PBS) using HAALD and PAHy without addition of crosslinker or catalyst. The pH and concentration of the reaction solution, considered as the important factors of the amine-aldehyde reaction, were changed to reveal the crosslinking rule. Thereafter, crosslinked hydrogels were characterized by gelation time, gel content, swelling ratio, and in vitro degradation. Furthermore, the modified polymers were characterized by Fourier transformed infrared (FTIR) spectroscopy to examine their structures. Results from scanning electron microscope (SEM) observations confirmed that a freeze-dried sample revealed a porous hydrogel structure with interconnected pores. The measurement of the cell adhesion confirmed the application potential of HAALD-PAHy hydrogels. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

多孔炭吸附剂的乙烯-乙烷选择性反转机制

烯烃是重要的化工原料,吸附分离技术可在温和工况下实现烯烃纯化,而吸附剂的烷烃选择性是实现高效化工分离过程的关键。基于分子模拟,提出调节孔道尺寸以控制多孔炭优先吸附乙烯或乙烷的选择性反转机制;控制活化条件,实验制备出不同孔径的多孔炭材料并验证了乙烯-乙烷选择性反转规律。结果表明,多孔炭的石墨化表面优先吸附乙烷;随着孔径尺寸的增大,可出现优先吸附乙烯的孔道区间;若孔径进一步增大,多孔炭可回归到优先吸附乙烷的石墨化表面吸附特征。选择性反转机制适用于不同形状的孔道结构。因此,可利用微孔孔道的限域作用放大多孔炭表面的烷烃选择性,并得到高性能的烷烃选择性吸附剂。     

提升生物质焦液相吸附容量的焦改性方法研究进展

生物质焦是生物质热化学转化过程中的副产品,是一种潜在的物理吸附剂,能够用作水处理吸附多种污染物。通过不同的改性方式,能够改变生物质焦的物理结构和化学特性,从而改变其对污染物的吸附脱除能力。本文在详细分析液相溶液吸附影响因素的基础上,总结了针对不同种类污染物,提升其吸附容量的有效生物质焦改性方法,包含热处理、添加试剂扩孔、超声波处理以及化学修饰和生物辅助等手段,并认为除孔隙特性外,生物质焦表面含氧官能团的化学特性同样对吸附起重要作用,如酸处理可增加焦表面酸性含氧官能团,并因阳离子交换作用而利于吸附金属离子;碱处理的焦表面因离域π电子密度提高,色散力增强,从而有利于吸附脱除酚酞、染料等有机污染物;而负载原子和化合物的焦能同时提升其对有机和金属污染物的脱除能力。此外,发现微生物作用下的生物吸附有助于脱除难降解的苯酚。该文为提升生物质焦吸附容量的改性方法选择提供了有效思路。