异丙醇镧引发对二氧环己酮开环聚合

脂肪族聚酯聚对二氧环己酮(PPDO)以其优异的生物降解性、生物相容性、生物可吸收性以及优异的柔韧性,成功应用于医用材料和环境材料领域。目前已有的PDO引发体系如辛酸亚锡,存在聚合速率慢、单体转化率不高等缺点。有机稀土类引发剂是目前倍受关注的一类活性很高的配位聚合引发剂,已经被成功应用于聚乳酸、聚己内酯等脂肪族聚酯的开环聚合中,具有反应速率快、单体转化率高、聚合物分子量分布窄等优点。本文将稀土类引发剂异丙醇镧(La(O^iPr)3)应用到PDO的开环聚合中,取得了较好的结果。     

聚十二烷二元酸丁二酯及其共聚酯的结晶行为研究

聚十二烷二元酸丁二酯是长碳链脂肪族聚酯中的一种新的聚合物材料．近年来，随着对环境问题的日益重视，利用脂肪族聚酯容易水解的特性，开发生物降解脂肪族聚酯材料的研究得到广泛开展．目前脂肪族二元酸酯的研究大多是围绕聚丁二酸酯、聚乙二酸酯及其共聚酯这一类降解速度较快的材料进行的．虽然这些聚酯已有部分商品化，但远远不能满足对特定降解速率材料的需求．长碳链脂肪族聚酯由于其具有类似PE的结构特征，又兼具聚酯的结构特征，有望在可降解包装材料、书籍装订、服装用热熔胶等方面获得广泛的应用．     

可生物降解抗污材料

研究和开发抗生物污染材料,降低蛋白质的非特异性吸附和微生物的附着生长,不仅可以大大提高仪器的灵敏度,降低植入材料在愈合过程中的副作用,如炎症和血栓等,还可以节省很多航海时所需的能源和动力。目前抗污染材料多为亲水性的聚乙烯醇、聚(N-乙烯基吡咯烷酮)、聚(2-口恶唑啉)、聚乙二醇和两性离子聚合物。虽然这些材料抗污染能力强,但是分子链大多为聚丙烯酸酯或聚丙烯酰胺,不具有可生物降解性。可生物降解抗污材料可通过将抗污功能分子引入到可生物降解的基质分子(如脂肪族聚酯、聚碳酸酯、聚多肽和多糖等)中得到。本文综述了可生物降解抗污材料的研究进展,首先介绍了生物污染的危害,抗生物污染材料的分类、特征和存在的问题。重点综述了可生物降解抗污材料的研究现状,从亲水性聚合物(如聚乙二醇、两性离子聚合物)和抗污剂具体阐述了可降解抗污材料的抗污机理、合成、结构和性能,并对可生物降解抗污材料的未来发展进行了展望。     

由脂肪族二酰胺二醇合成聚酯酰胺及表征

利用脂肪族二元酸酯与乙醇胺反应容易获得的对称二酰胺二醇,经缩聚合成聚酯酰胺预聚体,并针对端羧基和端羟基同时扩链来提高分子量,获得可生物降解的聚酯酰胺.首先将N,N′-二(2-羟乙基)草酰胺(HEOA)或N,N′-二(2-羟乙基)己二酰胺(HEHA)与己二酸和丁二醇缩聚,制备同时带有端羧基及端羟基的脂肪族聚酯酰胺预聚体,通过1,4-双(2-噁唑啉)苯及己二酰双己内酰胺混合扩链剂扩链,获得高分子量脂肪族聚酯酰胺,并通过红外、1H-NMR、DSC及TGA对其结构和热性能进行了表征.结果表明,预聚体在制备过程发生了一定的酯-酰胺交换反应;扩链后聚合物的熔点、熔融焓和热稳定性有所下降;但热稳定性仍接近或略高于聚己二酸丁二酯.     

脂肪族聚酯及共聚酯的生物降解性研究

以酯交换法或直接缩聚法合成了一系列脂肪族聚酯，经二异氰酸酯(HDI)扩链得到含氨酯键的聚酯及共聚酯，用DSC、X射线衍射等分析表征了聚酯及共聚物的结构和性能。用土埋试验、CO2释放试验和黑曲霉降解试验着重研究了这些聚合物的生物降解性，详细讨论了聚酯结构、组成及聚酯分子量对生物降解性的影响。     

脂肪族聚酯-酰胺的研究进展

脂肪族聚酯-酰胺（polyester-amides）合了聚酯和聚酰胺的优点,如具有优良的物理力学性能和加工性能等等。因此,对脂肪族聚酯-酰胺的研究成为近年来的研究热点。本文从脂肪族聚酯-酰胺的模型化合物（以双酰胺-二醇单体为例）的研究进展入手,分析了模型化合物的结构特点,以及模型化合物与相应聚合物之间的联系,从而为进一步研究聚合物打下一定的基础。本文还综述了脂肪族聚酯-酰胺的分类,各类脂肪族聚酯-酰胺的合成方法,以及脂肪族聚酯一酰胺在可生物降解材料和热塑性弹性体等领域的应用。     

开环可控聚合制备脂肪族聚酯的最新研究进展

近年来,作为生物降解高分子材料,脂肪族聚酯由于良好的生物降解性及生物相容性受到人们的广泛关注。脂肪族聚酯在环境友好材料和生物医用材料领域都具有极大的应用价值,目前,部分聚酯材料已经商品化。与此同时,脂肪族聚酯的合成方法尤其是活性开环聚合也成为学术界及工业领域的研究热点。采用开环聚合法得到的聚合产物化学组成精确、分子量分...     

三亚甲基碳酸酯基响应性脂肪族聚碳酸酯的研究进展

脂肪族聚碳酸酯是一类可生物降解、生物相容性的材料,在生物医药方面引起广泛关注。两亲性脂肪族聚碳酸酯聚合物中,聚碳酸酯部分凭借其疏水性能处于胶束内核部位,且该部分通过物理包覆、化学键合等方式使聚合物与药物相结合,提升了响应环境下药物运输与释放的方式与能力。因此,本工作对近年来响应性脂肪族聚碳酸酯的研究进展进行了综述,主要阐述了具有外环境刺激响应(pH、光、温度和氧化还原)脂肪族聚碳酸酯的合成、响应原理、在药物传递和释放方面的应用。     

生物降解高分子材料聚丁二酸丁二醇酯的改性研究进展

生物降解高分子材料被公认为是聚丙烯、聚乙烯等传统高分子材料造成"白色污染"的问题的重要解决方法之一。聚丁二酸丁二醇酯是重要的可生物降解的脂肪族聚酯之一,因与传统的聚丙烯、聚乙烯高分子材料具有相近的物理和力学性能,从而引起科学与工业界的广泛重视。然而,与大多数脂肪族聚酯一样,PBS材料也存在着加工、种类少、性能应用上的缺点。因此,对其通过改性拓宽用途范围的研究报道也随之增多。本文从化学、物理等改性的手段方法为着眼点,分类阐述了近些年来生物降解高分子材料聚丁二酸丁二醇酯改性研究现状与进展。     

新型官能团化聚己内酯的研究进展

聚己内酯(PCL)是一种具有良好药物透过性的可生物降解的脂肪族聚酯,是一类优良的药物载体.由于其结晶性强,亲水性差,生物降解速度慢,限制了其在组织工程等生物医用领域更广泛的临床应用.在PCL主链上引入功能性官能团既可有效地降低其结晶性、改善其亲水性、调控其降解速率,同时又可通过反应性官能团进行进一步的化学改性或生物活性化修饰,已成为生物可降解材料新的研究热点.本文综述了含侧基官能团己内酯单体的合成及其聚合反应,简要介绍了侧基官能团对聚己内酯性能的影响.     

RADIATION CROSSLINKING OF BIODEGRADABLE POLY(BUTYLENE SUCCINATE) AT HIGH TEMPERATURE

Poly(butylene succinate), (PBS) with different molecular weight was γ-irradiated at different temperatures and various doses. PBS with high molecular weight and smaller peak area of crystal melting gave the highest gel content at the same temperatures and dose. A two-step irradiation (irradiation in molten state after irradiation at room temperature) gave the highest gel content in different conditions. This is due to the formation of network structure by pre-irradiation at room temperature that leads to less degradation. PBS prepared by two step irradiation was effective for improvement of heat stability because of high gel content formation. Unirradiated PBS sheets broke immediately at 110°, while the irradiated sample (gel fraction, 50%) by a two step-method, did not break even up to 200 minutes at 130°C. The PBS sheets are biodegradable even after crosslinking.     

13C-NMR study of crosslinking and long-chain branching in linear polyethylene induced by 60Co gamma ray irradiation at different temperatures

H-type crosslinking and Y-type long-chain branching have been examined for linear polyethylene samples irradiate at different temperatures with ⁶⁰Co gamma rays in vacuum by solution-state ¹³C-NMR spectroscopy. In this study, relatively low molecular weight samples were irradiated with doses less than a gel dose in both solid and molten states. Resonance lines associated with H-links and Y-branches have clearly been observed for each irradiated sample and their radiation yields significantly depend on the irradiation temperature and the morphology of the samples. In particular, the G-value for the production of Y-branches is higher than that for H-links at lower temperatures, while the latter is superior to the former at higher temperatures. This may be due to the decrease in the concentration of the primary radicals, which are formed by main-chain scissions and associated with the production of Y-branches, by the recombination with small fragments at higher temperatures. The radiation yields of methyl branches and double bonds are also briefly discussed.     

Ultraviolet‐induced crosslinking of poly(butylene succinate) and its thermal property,dynamic mechanical property,and biodegradability

Crosslinking is an effective way to improve polymer properties. This paper focuses on ultraviolet‐induced crosslinking of poly(butylene succinate) (PBS) in the presence of a photoinitiator and a crosslinking agent at ambient temperature. The effects of the concentration of photoinitiator, the crosslinking agent content, and the irradiation time on the crosslink behavior were investigated. To obtain an appropriate gel fraction in different irradiation times, 3.0 wt% of photoinitiator and 10.0 wt% of crosslinking agent were proved to be the optimum choice. Furthermore, properties such as thermal properties, dynamic mechanical property, and enzymatic degradation of PBS before and after crosslinking were examined. Differential scanning calorimetry (DSC) analysis revealed that glass transition temperature (T_g) increased with increase in gel fraction, while melting temperature (T_m) and the degree of crystallinity decreased. This may be caused by the reduced molecular chain mobility and inhibited molecular motion for crystallization in crosslinked samples. The crosslinked polymer also showed improved thermal stability and dynamic mechanical property. In addition, the introduction of crosslinking retarded the enzymatic degradation rate of PBS, but it was still biodegradable. The improved properties of crosslinked PBS will extend the application of PBS. Copyright © 2009 John Wiley & Sons, Ltd.     

THE EFFECT OF IRRADIATION ON THE POLYETHERKETONE WITH CARDO GROUP

The effects of irradiation on the polyetherketone with cardo group (PEK-C) were studied. It was found that PEK-C can be crosslinked by irradiation under vacuum, while degradation reaction occurred in PEK-C at room temperature in the presence of air. Moreover. it was also found that Ts value of the crosslinked PEK-C at high temperature is higher than that at room temperature in the case of the same gel content, whose value is about 8℃higher than that of unirradiated PEK-C. The gelation dose of PEK-C at 300℃under vacuum is 1.5×10~4 Gy, which is about hundred times smaller than that at room temperature.     

热致型光敏液晶高分子在液晶场中光交联反应的研究

研究了具有肉桂酸酯侧链基的热致型液晶高分子的光交联行为．结果表明，在２０ｍｉｎ紫外光照射的条件下，形成液晶相的液晶高分子膜的光交联凝胶百分率要明显高于尚未形成液晶相的同种高分子膜．对形成液晶相的高分子膜，在环境温度低于液晶各向同性温度Ｔ时，温度对光交联凝胶百分率的影响甚微．这表明，由于液晶高分子中致介单元的聚集和有序排列形成的微区结构也影响了大分子链侧基肉桂酸酯的聚集状态．从而使其光化学性质发生变化．     

射频磁控溅射制备纳米TiO2薄膜的光电化学行为

在室温下采用射频磁控溅射法制备了纳米晶粒的TiO2薄膜,用循环伏安法研究了ITO/TiO2薄膜电极的光电化学行为,并测量了相应TiO2薄膜的亲水性与光催化能力.结果表明,在室温下制备的TiO2薄膜为无定形结构,当退火温度超过400 ℃时转化为锐钛矿结构.在400 ℃下退火的TiO2薄膜具有良好的亲水性和光催化能力. TiO2薄膜电极用254 nm的紫外光照射一定时间后会产生新的氧化峰,且随着光照时间的增加,峰电流也增加.初步认为用紫外光照射一定时间后, TiO2薄膜的循环伏安图的氧化峰属于光生的Ti3＋,而光致亲水性可能与Ti3＋的生成有关.     

Effect of vinyl acetate content and electron beam irradiation on the flame retardancy, mechanical and thermal properties of intumescent flame retardant ethylene-vinyl acetate copolymer

Ethylene vinyl acetate copolymer (EVA) flame retarded by ammonium polyphosphate (APP) and pentaerythritol (PER) was cross-linked by electron beam irradiation. The effects of vinyl acetate content and electron beam irradiation on the flame retardancy, mechanical and thermal properties of EVA composites were investigated. The volatilized products of EVA/APP/PER composites were characterized by thermogravimetric analysis/infrared spectrometry. As VA content increased, the volatilized products increased in the second decomposition step, but decreased in the third decomposition step. For all samples, the increase of irradiation dose could improve both the gel content and the Limit Oxygen Index (LOI, the minimum oxygen concentration by volume for maintaining the burning of a material) values of irradiated composites. The mechanical and thermal properties of the irradiated EVA composites were also evidently improved at appropriate irradiation dose as compared with those of unirradiated EVA composites, whereas these properties decrease at higher irradiation dose because of the electron beam irradiation-induced oxidative degradation or chain scission.     

辐照交联聚甲基乙烯基硅氧烷的ESR谱研究

本文研究了GY-131医用级聚甲基乙烯基硅氧烷(PMVS)在辐照交联中的自由基产生和衰减的ESR潜,以及SiO₂填料对交联的影响。     

Effect of gamma irradiation on ethylene–octene copolymers

Two ethylene–octene copolymers (POE) were irradiated with ⁶⁰Co gamma radiation and influence of irradiation atmosphere, absorbed dose and heat treatment of samples on the crosslinking were studied. Thermal properties and crystalline morphology of non-irradiated and irradiated POE were determined by using differential scanning calorimetry (DSC) and wide-angle X-ray diffraction (WAXS), respectively. The Charlesby–Pinner equation was used to describe the relationship between absorbed dose and sol fraction. The gel fraction of irradiated POE was lower and decreased with the increase of octene content when irradiated in oxygen, compared to irradiation in nitrogen atmosphere. The gel fraction increased significantly with the increasing of absorbed dose for the two copolymers. Heat treatment of samples prohibited the crosslinking of irradiated POE. The DSC results indicated that a subtle change of thermal properties of POE was observed before and after gamma irradiation at low dose. No change was found from the WAXS spectra of non-irradiated and irradiated POE. For heat-treating samples, the Charlesby–Pinner equation can not fit perfectly with the relationship between the sol fraction and absorbed dose, but it fits well with the crosslinking reaction of POE pellets.     

ESR study on free radicals trapped in crosslinked polytetrafluoroethylene (PTFE)

Free radicals in crosslinked PTFE which formed by ⁶⁰Co γ-rays irradiaion at 77 K and at room temperature were studied by electron spin resonance (ESR) spectroscopy. The crosslinked PTFE specimens with different crosslinking density were prepared by electron beam irradiation in the molten state. The ESR spectra observed in the irradiated crosslinked PTFE are much different from those in non-crosslinked PTFE (virgin); a broad singlet component increases with increasing the crosslinking density, G-value of radicals is much higher in crosslinked PTFE than in non-crosslinked one. Free radicals related to the broad component are trapped in the non-crystalline region of crosslinked PTFE and rather stable at room temperature, whereas radicals trapped in amorphous non-crosslinked PTFE are unstable at room temperature. It is thought that most of free radicals trapped in the crosslinked PTFE are formed in the crosslinked amorphous region. The trapped radicals decays around 383 K (110°C) due to the molecular motion of -relaxation.