Preparation and structure of crosslinked poly(methyl methacrylate-co-1,3-bis-(methacryloxymethyl)-1,1,3,3-tetramethyl disiloxane)

Summary An investigation is presented of the swelling, thermal and morphological characteristics of copolymers of methyl methacrylate and 1,3-bis-(methacryloxymethyl)-1,1,3,3-tetramethyl disiloxane. These materials were prepared by copolymerization/ crosslinking of the two monomers by gamma irradiation. Studies were performed on copolymers with mole fraction of the silicon-containing monomer ranging from 0.09 to 0.42.     

HEMA/NVP共聚水凝胶的合成与性能

以甲基丙烯酸2-羟乙酯(HEMA)和N-乙烯基吡咯烷酮(NVP)为原料,偶氮二异丁腈为引发剂,二甲基丙烯酸乙二醇酯(EGDMA)为交联剂,采用溶液聚合法合成HEMA／NVP共聚水凝胶。对其进行了红外光谱分析,考察了交联剂用量(EGDMA)和NVP用量等对该水凝胶材料性能的影响,研究表明该水凝胶具有良好的力学性能与合适的含水量,是一种性能良好的人工角膜材料。     

自硫化型丙烯酸酯橡胶的合成

在负离子型乳化剂的存在下,实现了丙烯酸（或甲基丙烯酸）／内烯酸乙酯／烯丙基缩水甘油醚（或甲基丙烯酸缩水甘油酯）的三元乳液共聚合,制得了主链上既带有羧基又带有环氧基的自交联型丙烯酸酯橡胶。用ＩＲ、＾１Ｈ－ＮＭＲ表征了共聚物的结构,用盐酸－丙酮法测定了共聚物中环氧基保留率。考察了多种金属离子、络合剂ＥＤＴＡ用量、交联点单体配体对共聚物凝胶质量分数的影响。     

Evaluation of the diethylene glycol bis(allyl carbonate)/acrylic acid copolymer behavior by solid‐state 13C‐NMR

The dynamic behavior of diethylene glycol bis(allyl carbonate) (CR‐39)/acrylic acid (AA) copolymers was evaluated by ¹³C high‐resolution solid‐state nuclear magnetic resonance (NMR). The NMR data showed that the copolymerization of CR‐39 and AA generated copolymers with different molecular behaviors as a function of AA content, which promoted changes in the crosslinking of CR‐39 chains and in the intramolecular forces. The copolymerization process influenced the sequence distribution and domain formation of the monomers, which is a consequence of the dispersion of comonomers along the macromolecular chains. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 740–745, 2005     

Cyclization in vinyl-divinyl copolymerization

It was found by analysis of the composition and n.m.r. behaviour of low-conversion soluble copolymers of styrene (S) with 5–60 wt% of ethylene dimethacrylate (EDMA) that cyclization strongly predominates in crosslinking copolymerization. The results suggest that, especially at a higher content of the divinyl component, compact structures are formed with the character of microgel-like particles. At a higher EDMA content, this component is incorporated into the copolymer only as a unit with a pendant double bond and the content of crosslinks (EDMA units with both vinyls reacted) does not further increase with increasing EDMA content. The pendant vinyls in the particle cores are already so immobilized or sterically hindered that they are unable to react even with small molecules of the monomer. Procedures for the determination of copolymerization parameters for pairs of mono- and divinyl monomers, usually neglecting cyclization, were revised. An analysis of the theoretical model of crosslinking copolymerization with weak cyclization and experimental results obtained with the S-EDMA system with prevailing cyclization show that the copolymerization parameters need not be too much distorted, if they have been determined from the content of the mono- and divinylic components of the copolymer.     

Redox-active liquid-crystalline ionomers: 1. Synthesis and rheology

Liquid-crystalline (LC) copolymers with redox-active groups were prepared by copolymerization of mesogenic and ferrocene-containing monomers (up to 10%). In these copolymers the ferrocene groups can be oxidized reversibly to prepare ionomers, while retaining the LC phase. It is thus possible to vary the amount of ionic groups in the ionomers by a redox reaction. The oxidized (charged) polymers show a strong excess X-ray scattering at small angles. This is typical for ionomers and is assigned to the scattering of ionic aggregates. Dynamic mechanical measurements show that these aggregates are effective as crosslinking points. Thus an oxidation-reduction reaction can be used to transfer an uncrosslinked polymer (reduced ferrocene groups, uncharged) reversibly into an oxidized polymer that acts like a weakly crosslinked gel.     

The study of modified poly(styrene-co-divinylbenzene) by inverse gaschromatographic analysis

For modified poly(styrene-co-divinylbenzene) the changes in supermolecular structure resulting from diluting the monomers during copolymerization with various amounts of inert diluents were studied. It has been found that the copolymers, obtained in the presence of substantial amounts of diluent, have a looser structure than those obtained with less diluent, as suggested by both the swelling measurements and the results of the inverse gas chromatographic (IGC) analysis. By this latter method it was found that the looser the copolymer structure, the broader was the range of adsorption-absorption nonequilibrium region and the lower was the heat of adsorption of normal aliphatic alcohols by the copolymers. Since the copolymers had the same crosslinking degree, no difference in their apparent glass transition temperatures were detected.     

硅烷交联聚氯乙烯的制备和性能

对由悬浮共聚合成的氯乙烯／乙烯基三乙氧基硅烷共聚树脂的水解交联行为和交联聚氯乙烯的性能进行了研究。结果发现，通过聚合过程添加pH调节剂可得到凝胶含量很低的氯乙烯／乙烯基三乙氧基硅烷共聚树脂；该类共聚树脂加工后有一定程度交联发生，凝胶含量随共聚树脂中乙烯基三乙氧基硅烷含量增加而增加；当加工样品在水中浸渍后凝胶含量又有较大幅度提高，说明水解交联的发生；交联后PVC高温力学性能和耐热变形性提高。     

Die polymerisation der lactame XI. Die copolymerisation von 6-caprolactam mit 12-laurolactam

The course of the incorporation of 6-caprolactam and 12-laurolactam into polymer chains during the hydrolytic, cationic and anionic copolymerization for an equimolar ratio of the monomers was studied. During the hydrolytic copolymerization 6-caprolactam is incorporated more rapidly at 260, 230 or 200°C at the beginning of the polymerization process; the differences between incorporation rates of the lactams into the copolymer increase with decreasing temperature. During the cationic copolymerization the incorporation of 12-laurolactam is more rapid by orders of magnitude for the above temperatures at the beginning of the process. Changes in the composition of cationic copolymers as compared to the hydrolytic copolymers are independent of the temperature during the copolymerization. The anionic copolymerization is characterized by a more rapid incorporation of 6-caprolactam into the polymer chain. The differences in the polymerization activity of the two lactams decrease with increasing temperature of the anionic copolymerization. The described course of incorporation of individual monomers, with the various mechanisms of the polymerization, also corresponds to melting points of copolymers in accordance with their composition.     

Random copolymers of propylene with 1,5-hexadiene containing only cyclopentane units in main chain and tailoring structure and mechanical properties of the copolymers

In the presence of [Ph₃C][B(C₆F₅)₄] and Triisobutylaluminium, dimethyl pyridylamidohafnium complex exhibited remarkable catalytic activity in the copolymerization of propylene with 1,5-hexadiene, affording high molecular weight copolymers with unimodal molecular weight distributions. More noticeably, the resultant copolymers contain absolutely cyclo-group in the polymer chains without pendent vinyl groups and crosslinking. The solid state structures and properties of the homogeneous copolymers were studied by examining melting behavior, wide-angle X-ray scattering, and tensile deformation. Chain microstructures were analyzed by ¹³C NMR spectra, and further confirmed by the measurement of reactivity ratios of the two monomers. These copolymers display a random distribution of the comonomer, and crystallinity decreases with increasing comonomer content. The copolymers contain variable amounts of comonomeric units, showing desired physical properties ranging from thermoplastic to elastoplastomeric to elastomeric.     

Synthesis and properties of new copolymers containing hindered amine

Eight new copolymers containing hindered amine (HA) were synthesized by copolymerization of vinyl monomers [styrene (St), methyl methacrylate (MMA)] with new functional monomers produced by reaction of 4-amino-2,2,6,6-tetramethylpiperidine (ATMP) and epoxy compounds containing double bond, and mixture copolymerization of vinyl monomers (St and MMA) with a mixture of ATMP and above epoxy compounds. The structure of these new copolymers were characterized by IR, NMR, and elemental analysis. The properties of these new copolymers were described and their photoprotecting effectiveness examined. Experimental results indicate that they possess high photoprotecting effectiveness comparable to or higher than that of a commercial polymeric HALS “PDS.” © 1996 John Wiley & Sons, Inc.     

Synthesis of superabsorbent copolymers as water manageable materials

Strongly water‐absorbing polymers based on the monomers acrylamide, potassium acrylate and magnesium methacrylate were prepared by copolymerization using ammonium persulfate as initiator and N,N‐methylene‐bisacrylamide (MBA) as crosslinking agent. The copolymers are synthesized by varying monomer, crosslinker and initiator concentrations. The experimental results shows that superabsorbents (SAPs) have good absorbency both in water and NaCl solutions. The copolymers are characterized by IR spectroscopy. Water retention in soil is enhanced by use of these superabsorbents. The SAPs use for the growth of sunflower plants is also investigated. The water retention capacity of the SAPs was carried out at 60 °C and 100 °C. Copyright © 2003 Society of Chemical Industry     

Properties of n‐butyl methacrylate copolymer latex films derived from crosslinked latex particles

Films obtained from copolymer latexes of n‐butyl methacrylate (BMA) with a series of crosslinking monomers [i.e., a macromonomer crosslinker (Mac), ethylene glycol dimethacrylate (EGDMA), and aliphatic urethane acrylate] exhibited differences in their tensile properties and swelling behaviors. For P(BMA‐co‐EGDMA) copolymer, a dependence on the initiator type was obtained. It is postulated that the network microstructures for the various copolymers evolved as the result of the copolymerization reactions between the monomer pairs during the synthesis in the miniemulsion free‐radical copolymerization. These network microstructures are, therefore, hypothesized to influence the mechanical properties of the resultant films. Copolymers prepared with Mac were tough in comparison with copolymers made with EGDMA. The presence of longer linear or lightly crosslinked poly(n‐butyl methacrylate) (PBMA) chains and the looseness of the crosslinked network structures in the PBMA‐co‐Mac copolymers appear to be the factors responsible for the differences. All of the copolymer films disintegrated into swollen individual microgels when they were immersed in tetrahydrofuran. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 42–49, 2003     

Ring‐opening copolymerization and properties of polycarbonate copolymers

A series of polycarbonate copolymers were synthesized by the ring‐opening bulk polymerization of 2‐phenyl‐5,5‐bis(hydroxymethyl) trimethylene carbonate (PTC) and 5,5‐dimethyl trimethylene carbonate (DTC) with tin(II) 2‐ethylhexanoate and aluminum isopropoxide as initiators. The copolymers obtained were characterized by ¹H‐NMR, Fourier transform infrared, and ultraviolet. The influence of the molar ratio of the monomers, the initiators, and their concentrations, the reaction time, and the reaction temperature on the copolymerization was also studied. The copolymerization of monomers DTC and PTC was a nonideal copolymerization, and the copolymerization reactivity ratio of the monomer DTC was higher than that of PTC in the copolymerization process. In vitro release profiles of fluorouracil from the copolymers showed that the copolymer had a steady drug‐release rate and good controlled‐release property. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2008     

Miniemulsion copolymerization of n‐butyl methacrylate with crosslinking monomers

Miniemulsion copolymerization of n‐butyl methacrylate and crosslinking monomers such as a macromonomer crosslinker (Mac), ethylene glycol dimethacrylate (EGDMA), or an aliphatic urethane acrylate macromonomer (AUA) was utilized to obtain crosslinked latex particles. The crosslinking monomers were added at 0.2 mol %, on the basis of the amount of n‐butyl methacrylate utilized in a polymerization. The development of the gel content during the copolymerization reaction differs depending on the type of the crosslinking monomer. In addition to the crosslinking reactions between the n‐butyl methacrylate and the crosslinking monomers, other kinetic events, such as microphase separation, may have occurred, giving rise to different particle morphologies, dependent on the type of initiator used (i.e., oil‐soluble or water‐soluble). © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 1721–1730, 2001     

Hydrogels based on graft copolymers of collagen synthesis

Graft copolymerization of 2-hydroxyethyl methacrylate in combination with hydrophobic monomers onto soluble collagen was employed in the synthesis of hydrogels. The hydrogels were formed by simultaneous graft copolymerization and crosslinking. In order to study the effect of various crosslinking agents on the water retention character of the hydrogels, three different crosslinking agents, namely, N,N′-methylene bis acrylamide, 1,4-butanediol dimethacrylate, and hexamethylene urethanediacrylate were used. Hexamethylene urethanediacrylate crosslinked systems require a minimum amount of crosslinking agent to attain maximum water content in comparison to the other systems.     

Free radical copolymerization of allyloxyphenylsiloxanes with some vinyl monomers

Two p-allyloxyphenyldisiloxane compounds, 1-(p-allyloxyphenyl)-1,1,3,3,3-pentamethyldisiloxane (mono-APDS) and 1,3-bis(p-allyloxyphenyl)-1,1,3,3-tetramethyldisiloxane (bis-APDS), were synthesized to study their radical copolymerizations with some vinyl monomers (styrene, methyl methacrylate, N-phenylmaleimide and maleic anhydride). The reactivities of allyl groups in mono-APDS and bis-APDS were found to be almost the same in styrene and methyl methacrylate copolymerization, as evidenced by their composition curves, and increase with the electron-accepting ability of comonomers. In the case of electron-poor monomers, such as N-phenylmaleimide and maleic anhydride, the second allyl group of bis-APDS readily took part in the crosslinking. Differential scanning calorimetry and thermogravimetry revealed that the increase of APDS contents in those copolymers led to lower glass transition temperature (T_g) and higher thermal degradation temperature.     

Principles and limits of polymer latex tailoring

The preparation of a synthetic latex is a very complex process that is affected by the monomers selected, surfactants, initiators and the polymerization process. The semi-continuous process is the most frequent as it enables the control of the polymerization heat removal as well as the control of the composition of the copolymers comprising several types of monomer units. Some aspects of copolymerization in emulsion and particle growth in the case of the semi-continuous process are discussed. Copolymers usually comprise 4–5 comonomers, some of them with functional groups. Functional groups serve as loci for crosslinking, improve colloid stability, increase polarity, improve adhesion, cause alkali-solubility and/or alkali-swellability. High value polymer latices with special particle morphology, composition and other characteristics can be tailor-made by using special polymerization recipes that are still mostly empirical.     

氟烯烃共聚合的研究进展

概述了氟烯烃共聚物树脂的发展,总结了氟烯烃与其他单体共聚合的相关研究。大多数情况下,氟烯烃单体的共聚反应得到的是随机共聚物。虽然聚合反应涉及的含氟单体和共聚单体种类很多,但最终聚合物按其性能和应用主要包括热塑性体、弹性体和热塑性弹性体3类。通过筛选一些特定功能性的单体参与聚合反应,可以使得含氟聚合物的某些性能如溶解性、交联固化性、附着力等得到补偿。此外,文中列出了一些氟烯烃单体的Q-e参数,并从理论上讨论了共聚物的结构;简述了吸电子氟烯烃单体与供电子全质子单体间的交替共聚行为,并列举了具体实例。     

偏光片用丙烯酸酯压敏胶粘接性能和老化性能研究

针对偏光片用压敏胶对耐老化性能的特殊要求,采用丙烯酸丁酯、丙烯酸异辛酯、甲基丙烯酸甲酯、甲基丙烯酸羟丙酯、丙烯酸等单体通过溶液聚合的方法,制得了不同的丙烯酸酯压敏胶（PSA）。讨论了引发剂、丙烯酸、交联方法等因素对PSA光学性能、粘接性能、热老化及湿热老化性能的影响。当BPO用量为单体总量的为0.6%,AA用量为0.5%,IPDI用量为固含量的3%时,制备的压敏胶具有适宜的粘接性能。湿热老化前后,PET基材压敏胶的剥离强度分别为7.76N/25mm、6.36N/25mm,具有较高剥离强度保持率。该压敏胶用于偏光片和玻璃板贴附时,显示出优良的湿热老化性能。