隆羧酸硅基酯的合成及其可降解性质的研究进展

综述了聚羧酸硅基酯的合成方法和降解性质。用于合成聚羧酸硅基酯的方法主要有AA／BB型硅基转移酯基交换法、AB型硅基转移酯基交换法、AB型硅氢化反应以及交叉去氢偶联反应。对上述方法的特点进行了总结和比较。详细介绍了该类聚合物的降解机理以及影响降解速率的因素，并对其在生物医学以及环境科学领域的应用进行了展望。     

可降解聚硅基酯的合成及与苯乙烯的交联反应

采用二元羧酸与二元氯硅烷缩聚制备聚硅基酯的方法,将富马酸二叔丁基酯与1,3-二氯-四甲基二硅氧烷反应合成了黏性液态的不饱和聚(富马酸-四甲基二硅氧烷硅基酯);以偶氮二异丁腈作为引发剂,将该聚硅基酯与苯乙烯进行交联反应,黏性液态的聚硅基酯交联后转变成固态。通过傅里叶变换红外光谱、差示扫描量热法和热重法对聚硅基酯及其与苯乙烯的交联产物进行了分析,结果表明交联后的产物比未交联聚硅基酯的玻璃化转变温度明显升高,热稳定性增强。     

可降解材料聚(己二酸二甲基硅基酯)的合成及表征

以己二酸和二甲基-二乙酰氧基硅烷为单体,采用熔融缩聚法合成了聚(己二酸二甲基硅基酯),并通过1H-核磁共振、差示扫描量热法、热重分析、凝胶渗透色谱对聚合物进行了表征。结果表明,聚(己二酸二甲基硅基酯)的重均分子量为4 021,分子量分布指数为2.10,玻璃化转变温度为-42.186℃,热稳定性较好,其在四氢呋喃水溶液中不稳定,随着放置时间的延长,降解速率变缓。     

硅脲与醇和羧酸的反应

介绍了硅烷化试剂Ｎ、Ｎ’－双三甲基硅脲的合成反应机理,研究了它与５种醇和７种羧酸的反应。结果表明,以二氯甲烷为溶剂,在室温或４０℃下,Ｎ,Ｎ’－双三甲基硅脲可与醇或羧酸平稳反应,三甲基硅烷基醚的收率在９０％以上,三甲基硅烷基酯的收率在８０％以上。     

超高强混凝土中各组分与聚羧酸系超塑化剂之间的相互作用(英文)

超高强混凝土(ultra-high strength concrete,UHSC)的水灰比小于0.25,含有大量的硅灰等微细组分,这有利于颗粒的最优紧密堆积。硅灰的表面化学效应以及较大的表面积使其成为UHSC中最难被分散的组分。由甲基丙烯酸、甲基丙烯酸酯及甲代烯丙基磺酸合成的聚羧酸系超塑化剂能使水泥颗粒被有效润湿,然而烯丙醚-马来酸酐合成的聚羧酸系超塑化剂可以很好地分散硅灰。这2种不同的聚羧酸系超塑化剂的复合可以使其拥有不同的分子结构,从而赋予超高强混凝土很好的流动性。当只加入1种聚羧酸系超塑化剂时其掺量为1%(质量分数,下同),而当加入这种复合聚羧酸系超塑化剂时掺量为0.5%就足够了。这2种类型的聚羧酸系超塑化剂的协同效应是由于它们的选择性吸附:甲基丙烯酸盐基的聚羧酸系超塑化剂主要吸附在水泥颗粒表面,而烯丙醚基聚羧酸系超塑化剂主要吸附在硅灰颗粒表面。实验表明:小分子量的有机酸阴离子(如:柠檬酸盐、葡萄糖酸盐及酒石酸盐中的阴离子)与聚羧酸系超塑化剂之间具有潜在的协同作用。只需加入0.1%的这些阴离子即可显著提高烯丙醚基聚羧酸系超塑化剂的作用效果。这些阴离子可以起到一种辅助作用,它们同时吸附在水泥颗粒表面以及硅灰颗粒表面。水泥颗粒的表面首先由这些阴离子所占据,而硅灰颗粒表面吸附了烯丙醚基聚羧酸系超塑化剂和这些阴离子。这些阴离子起到了一种很强的静电分散效应,使烯丙醚基聚羧酸系超塑化剂的空间位阻效应得到加强。虽然聚羧酸系超塑化剂阴离子具有缓凝作用,但是使用这种复合聚羧酸系仍能制备出高早强混凝土。     

含膦基抗泥保坍型聚羧酸减水剂的合成及性能研究

通过两步连续酯化的方法制备了含膦基聚羧酸减水剂,通过红外光谱对合成的含膦基聚羧酸减水剂的分子结构进行表征,并对其进行水泥净浆流动度、胶砂扩展度以及混凝土性能测试。     

有机硅化合物在合成中的应用

有机硅化学的研究方向主要有两个方面,一是有机硅化合物的制备及结构的研究,二是有机硅化合物作为合成试剂与保护基在合成中的应用.文章以有机硅化合物中研究得较为活跃的反应和试剂为基础,重点从这两个方面介绍有机硅化合物在合成中的应用.包括有机硅化合物的合成,叠氮基、硅氰基和杂环的引入,羧酸酯的合成与碳氧键的断裂,羟基、羰基、羧基、巯基、炔基和氨基的保护以及硅叶立德的应用.     

线性PBS基脂肪族聚酯的合成和降解研究

为了探讨线性PBS基脂肪族共聚酯的结构和降解之间的关系,首先合成了线性PBS基脂肪族共聚酯,即聚丁二酸丁二醇酯-共-聚己二酸丁二醇酯P(BS-co-BA),聚丁二酸丁二醇酯-共-癸二酸丁二醇酯P(BS-co-BSe),并将线性PBS基脂肪族共聚酯及PBS在土壤悬浮液中进行降解,通过GPC、熔点测定仪对线性PBS基脂肪族共聚酯的分子量和熔点进行了测定;通过测定降解过程中失重率和降解前后聚酯薄膜表面形貌来对共聚酯降解程度进行表征。结果表明:随着二元酸碳链的增长,分子对称性降低,降解性能增大。通过观察分子量,熔点及降解失重率的测定结果,得出分子量越大,降解越不容易进行;熔点越小,降解性能越好。     

蔗糖酯改性水泥基复合材料的合成和性能表征

合成了一种新的单体蔗糖酯,并通过化学接枝将其引入聚羧酸减水剂主链上合成蔗糖酯改性的聚羧酸减水剂,通过蔗糖酯的引入,改善了传统聚羧酸减水剂适应性差、试块后期强度不足的问题。通过自由基聚合反应,考察了不同反应条件对产物性能的影响,得出其最佳合成条件为:甲代烯丙基聚氧乙烯醚、丙烯酸、甲基丙烯酸蔗糖酯的量比为1∶4∶1.0,反应时间为5h,反应温度为50℃,引发剂质量分数为4%。后期混凝土性能测试表明,蔗糖酯改性减水剂的水泥净浆流动度相比于未改性聚羧酸减水剂的水泥样品有很大提高;抗压强度和抗折强度测试表明,蔗糖酯改性减水剂可以有效提高水泥试块的后期抗压、抗折强度;扫描电镜(SEM)分析测试表明,蔗糖酯改性聚羧酸减水剂有利于针状钙矾石的生成,从而提高水泥基体后期强度。     

超支化聚合物的研究及应用

以二异丙醇胺（DIPA）及酸酐为原料合成了含有一个羧基、两个羟基的AB2型单体,采用AB2型单体自缩聚的方法合成了超支化聚酰胺酯,然后用甲基丙烯酸对超支化聚酰胺酯的端基功能改性。然后将超支化单体与马来酸酐、甲基丙烯酸共聚合成阻垢分散剂。     

Crosslinking of poly(silyl ester)s containing fumaryloxyl units in the main chain and characteristics of the crosslinked products

Two unsaturated poly(silyl ester)s that contained innoxious fumaryloxyl units in the main chain were prepared by the polycondensation reaction of 1,5‐dichloro‐1,1,5,5‐tetramethyl‐3,3‐diphenyltrisiloxane or 1,3‐dichlorotetramethyldisiloxane with di‐tert‐butyl fumarate under nitrogen at 100°C for 1–3 days. To investigate the crosslinking reaction of the unsaturated poly(silyl ester)s, the two unsaturated poly(silyl ester)s were crosslinked in the presence of 2,2′‐azobisisobutyronitrile as a radical initiator. After the crosslinking, the unsaturated poly(silyl ester)s, which were viscous liquids, turned into solid products. The characterization of the two poly(silyl ester)s and the crosslinked products included infrared spectroscopy, ¹H‐NMR spectroscopy, differential scanning calorimetry, and thermogravimetric analysis. Comparisons were made between the linear poly(silyl ester)s and the crosslinked poly(silyl ester)s. After the crosslinking, the important resonance signal for ethenylene (C?C) disappeared, and this showed that the crosslinking reaction was carried out progressively. The glass‐transition temperatures of the crosslinked poly(silyl ester)s were higher than those of the uncross‐ linked poly(silyl ester)s, and the thermal stability of the crosslinked poly(silyl ester)s was better than that of uncrosslinked poly(silyl ester)s. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 1221–1225, 2007     

Facile method towards functionalization of partially fluorinated polyarylethers via sequential post-polymerization modification

A novel partially fluorinated arylene vinylene ether (FAVE) polymer containing ester groups was synthesized, which was used to prepare three reactive FAVE polymers containing carboxylic acid groups, alcohol groups, and acid chloride groups, respectively. Post-polymerization modifications of the FAVE polymer's carboxylic acid groups (via a DCC coupling procedure with the desired alcohol), alcohol groups (via DCC coupling or an acid chloride esterification procedure with the desired carboxylic acid or acid chloride), and acid chloride groups (via an optimized nucleophilic substitution reaction with the desired alcohol or amine) were successfully performed. Several examples have been successfully prepared to demonstrate the versatility of these developed modification methods. FAVE polymers have been prepared with NHS active ester groups, Disperse Red 1 chromophores, benzyl bromide groups, aryl trifluorovinyl ether groups, ATRP initiator groups, vinyl groups, propargyl groups, Disperse Orange 3 chromophores, and benzaldehyde groups. In most cases, analytical data are consistent with a quantitative conversion of the reactive or functional groups. It is demonstrated that no degradation of the FAVE polymer matrix occurs after multistep post-polymerization modification reactions.     

NMR based determination of minute acid functionality: end-groups in PET

Conditions are determined for the carbodiimide-mediated room temperature esterification of the carboxylic acid end-groups of poly(ethylene terephthalate) with hexafluoroisopropanol. The hexafluoroisopropyl ester is quantified with ¹⁹F NMR, using α,α,α-trifluorotoluene as a secondary standard. This provides a technique for accurate determination of minute amounts of carboxylic acid functionality in small samples of polymers, and potentially in animal and plant based foods.     

Poly(silyl ester)s: A new route of synthesis via the condensation of Di‐tert‐butyl ester of dicarboxylic acid with dichlorosilane

Poly(silyl ester)s were synthesized by a new route via the condensation of di‐tert‐butyl ester of dicarboxylic acid with dichlorosilane by the elimination of tert‐butyl chloride as a driving force. Three new poly(silyl ester)s with molecular weights typically ranging from 2000 to 5000 amu were produced by the condensation of di‐tert‐butyl adipate with 1,5‐dichloro‐1,1,5,5‐tetramethyl‐3,3‐diphenyl trisiloxane and di‐tert‐butyl fumarate with 1,5‐dichloro‐1,1,5,5‐tetramethyl‐3,3‐diphenyl trisiloxane or 1,3‐dichlorotetramethyl disiloxane. Each polymer was characterized with infrared, ¹H‐NMR, and ¹³C‐NMR spectroscopy, gel permeation chromatography, differential scanning calorimetry, and thermogravimetric analysis. This new approach showed several advantages. First, it did not require a catalyst or solvent. Second, the tert‐butyl chloride byproduct was volatile and was easily eliminated. Third, there was no reaction between the growing poly(silyl ester)s and the condensation byproduct, tert‐butyl chloride. Fourth, the monomers could be readily purified. Finally, the polymerization could be performed at relatively low temperatures and in a short time. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 1378–1384, 2006     

Synthesis and characterization of hyperbranched poly(silyl ester)s

Hyperbranched poly(silyl ester)s were synthesized via the A₂ + B₄ route by the polycondensation reaction. The solid poly(silyl ester) was obtained by the reaction of di‐tert‐butyl adipate and 1,3‐tetramethyl‐1,3‐bis‐β(methyl‐dicholorosilyl)ethyl disiloxane. The oligomers with tert‐butyl terminal groups were obtained via the A₂ + B₂ route by the reaction of 1,5‐dichloro‐1,1,5,5‐tetramethyl‐3,3‐diphenyl‐trisi1oxane with excess amount of di‐tert‐butyl adipate. The viscous fluid and soft solid poly(silyl ester)s were obtained by the reaction of the oligomers as big monomers with 1,3‐tetramethyl‐1,3‐bis‐β(methyl‐dicholorosilyl)ethyl disiloxane. The polymers were characterized by ¹H NMR, IR, and UV spectroscopies, differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). The ¹H NMR and IR analysis proved the existence of the branched structures in the polymers. The glass transition temperatures (T_g's) of the viscous fluid and soft solid polymers were below room temperature. The T_g of the solid poly(silyl ester) was not found below room temperature but a temperature for the transition in the liquid crystalline phase was found at 42°C. Thermal decomposition of the soft solid and solid poly(silyl ester)s started at about 130°C and for the others it started at about 200°C. The obtained hyperbranched polymers did not decompose completely at 700°C. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 3430–3436, 2006     

Paper wet performance and ester crosslinking of wood pulp cellulose by poly(carboxylic acid)s

Poly(carboxylic acid)s have been used as crosslinking agents for wood pulp cellulose to increase the wet strength of paper. In this research, we evaluated the effects of two multifunctional carboxylic acids, i.e., 1,2,3,4-butanetetracarboxylic acid (BTCA) and poly(maleic acid) (PMA), on the wet strength retention, dimensional stability, wet stiffness, and folding endurance of the treated paper. We observed that the wet strength retention, dimensional stability, and wet stiffness of the treated sheets increase, whereas the folding endurance decreases as the poly(carboxylic acid) concentration applied to those sheets increases. We measured the ester carbonyl band absorbance in the spectra of the treated paper. The linear correlation between the ester carbonyl band absorbance and wet strength, dimensional stability, and wet stiffness indicates that the improvement in the wet performance of the treated paper is directly attributed to the ester crosslinking of the wood pulp cellulose by poly(carboxylic acid)s. The data presented in this article also indicate that FTIR spectroscopy can be used for predicting the performance of the paper crosslinked by poly(carboxylic acid)s. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 67: 649–658, 1998     

Infrared spectroscopy studies of the effects of the catalyst on the ester cross-linking of cellulose by poly(carboxylic acids)

The esterification of cellulose by a poly(carboxylic acid) proceeds in two steps: the formation of a 5-membered cyclic anhydride intermediate by the dehydration of two carboxyls, and the reaction between cellulose and the anhydride intermediate to form an ester. Sodium hypophosphite is the most effective catalyst for the esterification. The effect of sodium hypophosphite on the esterification of cotton cellulose was studied by Fourier transform infrared spectroscopy (FTIR). It was found that sodium hypophosphite accelerates both the formation of the cyclic anhydride intermediate and the reaction between the anhydride intermediate and cellulose. The chief role of sodium hypophosphite is possibly the acceleration of the esterification of cellulose by the anhydride intermediate. © 1993 John Wiley & Sons, Inc.     

Multiple hydrophilic polymer ultra-thin layers covalently anchored to polyethylene films

A novel procedure has been developed to covalently graft multiple hydrophilic polymer ultra-thin layers to functionalized polyethylene surface. Polyethylene films have been functionalized by two methods, chromic acid oxidation and maleic anhydride grafting, to produce surfaces containing reactive groups, carboxylic acid and anhydride, respectively. The reactive groups formed in the functionalization were used to anchor a poly(vinyl alcohol) (PVA) ultra-thin layer by thermal esterification. After anchoring PVA, a second ultra-thin layer, constituted of poly(acrylic acid) (PAA), was also anchored. The second layer was anchored by thermal esterification between PVA hydroxyl groups and PAA carboxylic acid groups. The procedure presented in this work allows the formation of an ultra-thin layer. The macromolecule anchoring reactions occur only at the interfaces, consequently, only the macromolecules in contact with the interface are anchored. The formation of the ultra-thin layer and the surface characteristics have been analyzed through XPS, ATR-FTIR, SEM, and AFM data.     

Biodegradation of poly(3‐hydroxybutyrate‐co‐4‐hydroxybutyrate) by a novel P3/4HB depolymerase purified from Agrobacterium sp. DSGZ

A poly(3‐hydroxybutyrate‐co‐4‐hydroxybutyrate) (P3/4HB)‐degrading strain, Agrobacterium sp. DSGZ, was isolated from sewage by poly(3‐hydroxybutyrate) (PHB) mineral agar plates. A novel P3/4HB depolymerase with a molecular weight of 34 kDa was purified through a novel single‐step affinity chromatography method from the culture supernatant of the strain by using P3/4HB powder as a substrate. The purified depolymerase showed optimum activity at pH 7.0 and 50°C, and was stable at the pH range of 6.0 to 9.0 and temperature below 50°C. Enzyme activity was strongly inhibited by phenylmethylsulfonyl fluoride (PMSF), ethylenediaminetetraacetic acid (EDTA), hydrophobic reagents, and some metal ions. The depolymerase degraded poly(3‐hydroxybutyrate) (PHB), poly(hydroxybutyrate‐co‐hydroxyvalerate) (PHBV), P3/4HB, and polycaprolactone (PCL), instead of polylactic acid (PLA) or poly(butylene succinate) (PBS). Meanwhile, the depolymerase showed high hydrolytic activity against short‐chain length esters, such as butyrate acid ester and caprylic acid ester. The main degradation products of the depolymerase were identified as hydroxybutyrate monomers and dimers, and the monomers were identified as 3‐hydroxybutyrate (3HB) monomers and 4‐hydroxybutyrate (4HB) monomers. The preparation procedure, crystallinity, and 4HB composition of the P3/4HB copolymer showed evident effect on degradation behavior, and change in crystallinity was the main factor affecting degradation. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 42805.