Synthesis and properties of p（NIPA-co-NVP）/clay hydrogels by radiation polymerization

In this study, hydrogels of P（NIPA-co-NVP）/clay were synthesized by γ-ray radiation. Different thermo-sensitive hydrogels were made under different experimental conditions such as dose, monomer ratio, and content of clay. X-ray diffraction shows that the layer distance between Na-clays is changed from 1.6 to 2.7 nm because Na-clay pieces can be intercalated or exfoliated by HTMAB, and that between P（NIPA-co-NVP）/clay pieces is 3.4 nm. The swelling property tests show that the LCST of P（NIPA-co-NVP） is higher than PNIPA. With the increase of NVP content, LCST is higher. As the ratio of NIPA/NVP is 95/5, hydrogel shows the best swelling property and LCST is 37℃. LCST of P（NIPA-co-NVP）/clay hydrogel is not changed, but the strength and swelling properties are better.     

PVA/PVP/ws-chitosan水凝胶伤口敷料的辐射制备及性能表征

采用γ射线辐射法制备了聚乙烯醇(PVA)/聚乙烯基吡咯烷酮(PVP)脉溶性壳聚糖(ws-chitosan)共混水凝胶.研究了辐射剂量、ws-chitosan含量及增塑剂(聚乙二醇(PEG)或甘油)对水凝胶性能的影响.实验发现,随着辐射剂量的增大,凝胶分数增大,并在剂量大于27 kGy时达到饱和;ws-chitosan含量增大及加入增塑剂PEG或甘油后,水凝胶的凝胶分数和强度都会减小,而相应的溶胀度会显著增大.通过高级流变仪(ARES)对水凝胶弹性模量的测试显示,随吸收剂量的增加,凝胶强度会相应增大,但在27 kGy以上出现饱和.     

IPN’s of acrylic acid and N-isopropylacrylamide by gamma and electron beam irradiation

Interpenetrating networks (IPN) of temperature sensitive N-isopropylacrylamide (NIPAAm) and pH sensitive acrylic acid (AAc) monomer were prepared in two consecutive steps. Hydrogels of AAc were synthesized by gamma radiation from a ⁶⁰Co gamma source and an electron beam from a Van de Graaff accelerator. A second hydrogel of NIPAAm was synthesized within the first AAc hydrogel by polymerization and cross-linking with a redox initiator and cross-linking agent. The thermal and pH sensitivity of the hydrogels were determined by measuring the swelling, and the morphology and composition by SEM.     

Vitamin C hinders radiation cross-linking in aqueous poly(vinyl alcohol) solutions

Poly(vinyl alcohol) (PVA) is a promising semi-crystalline material for biomedical applications. It is soluble in water and can be formed into hydrogels by freezing and thawing or crystallizing from an aqueous theta solution such as that of polyethylene glycol (PEG). Radiation cross-linking caused by sterilization or high dose irradiation of concentrated PVA solutions could compromise some properties of these hydrogels. Therefore, we hypothesized that radiation cross-linking of PVA solutions and PVA-PEG theta gels could be prevented by using the antioxidant vitamin C as an anticross-linking agent. Our hypothesis tested positive. Vitamin C concentrations of 0.75 and 4.5 mol/mol of PVA repeating unit could prevent cross-linking in 17.5 wt/v% PVA solutions made with PVA molecular weight of 115,000 g/mol irradiated to 25 and 100 kGy, respectively. Vitamin C also prevented cross-linking in 25 kGy irradiated PVA-PEG theta gels containing up to 5 wt% PEG and decreased the viscosity of those up to 39 wt%.     

辐射合成法合成明胶类水凝胶及其性能研究

采用辐射法合成了明胶/羧甲基纤维素钠（CMC-Na）/聚乙烯吡咯烷酮（PVP）水凝胶,利用索氏提取器、紫外-可见分光光度计以及原子光谱仪分别对其溶胀性、pH值敏感性、凝胶含量及其对Cr（Ⅵ）的吸附性能进行了测试分析。在剂量率约为83 Gy/min,吸收剂量为15、25、35和45 kGy条件下,明胶/CMC-Na/PVP质量比为4∶1∶2、4∶1∶5和2∶1∶5的明胶/CMC-Na/PVP水溶液经辐照均能交联合成水凝胶。在高纯水中,该类水凝胶溶胀率分布于11～56之间;在pH=1的高氯酸溶液中,所有凝胶的溶胀率较之水溶液中均有所下降,说明这类水凝胶对pH值敏感。不同原料比例生成的水凝胶,其溶胀率并未随吸收剂量的增大而呈现出明显的增加。比例为4∶1∶5的水凝胶溶胀性能最为优良,其溶胀率最大值为56。合成的明胶/CMC-Na/PVP水凝胶可在1个月内完全腐化分解,说明在PVP中添加明胶和CMC-Na后,引入了天然高分子材料优良的降解性能,加速了凝胶分解,缩短了降解时间。同时,发现该类凝胶具有极强的吸Cr（Ⅵ）能力,可达0.539 g/g。     

用辐射技术制备丙烯酰胺与丙烯酸钠共聚物水凝胶——超级吸水材料

本文描述了丙烯酰胺—丙烯酸钠水溶液辐射共聚—交联制备共聚物水凝胶的研究。在共聚体系中加入少量非离子型表面活性剂,可把单体浓度由通常的20％上下提高到50％,聚合转化率和共聚物的特性粘数也都有相当程度的提高。这一体系经辐射共聚—交联后,可得到溶胀比>1,000的共聚物水凝胶——超级吸水材料。这种共聚物水凝胶的溶胀比不仅受吸收剂量即交联密度的制约,而且与共聚物中羧钠基的含量有密切关系。     

聚硅氧烷改性氧化石墨烯的辐射制备及其在导热硅橡胶中的应用研究

将氧化石墨烯和乙烯基三乙氧硅烷（TEVS）混合液进行γ射线辐照处理,制备聚硅氧烷功能化的改性氧化石墨烯（GO-Si）,并通过红外光谱（FT-IR）、拉曼光谱（Raman）表征分析GO-Si的结构。在辐照时,随着吸收剂量增加,聚硅氧烷的接枝量也随之增加;由于TEVS的接枝聚合,GO-Si表面的聚硅氧烷含量明显提高。将GO-Si和羟基硅油共混,制备室温固化的硅橡胶/改性氧化石墨烯复合材料（SR/GO-Si）,与未改性氧化石墨烯（GO）相比,GO-Si与硅橡胶基体相容性更好,分散更加均匀。对SR/GO-Si和纯SR的力学性能、导热性能和辐照效应进行对比分析,结果表明,GO-Si的引入可以明显提高复合材料的综合性能,导热系数从0.13 W•m^-1•K^-1提高至1.1 W•m^-1•K^-1,拉伸强度提高了149%。在90 kGy辐照条件下,GO-Si的引入对复合材料的辐照效应起到积极作用,提高了拉伸强度和硬度,SR/GO-Si有望在低剂量辐射环境下作为电子封装热界面材料使用。     

Synthesis, characterization and adsorption study of the uranyl ions by hydrogels based on polyethylene glycol and methacrylic acid copolymers

The water swelling polymeric hydrogels were obtained by γ-initiated radiation copolymerization of polyethylene glycol (PEG) with methacrylic acid (MAA) and three-ethylene glycol dimethacrylate (TEGDMA) as cross-linking agent. The main regularities of PEG-MAA network formation, deformation properties, structure and thermal characteristics depending on copolymer composition, molecular weight of PEG have been studied. The sorption of uranyl ions by PEG-MAA hydrogels in comparison with homopolymer PMAA was investigated. The effect of uranyl ions concentration on sorption efficiency of hydrogels was shown. The ability to regeneration in desorption process was demonstrated for PEG-MAA hydrogels in comparison with PMAA gel.     

Effect of maleic acid content on the thermal stability, swelling behaviour and network structure of gelatin-based hydrogels prepared by gamma irradiation

The highly swelling Poly (acrylamide/maleic acid/gelatin) P(AAm/MA/G) hydrogels were prepared by gamma-irradiation at low dose rate (0.94 kGy/h) and moderate dose rate (3.84 kGy/h). The hydrogels were confirmed by FTIR. The effect of copolymer composition, dose and dose rate on the swelling behaviour was discussed. Increasing of MA content and G in the initial mixture leads to an increase in the amount of MA and G in the gel system and decrease in the gelation %. The swelling behaviours of the hydrogel prepared at moderate dose rate increased with increasing MA mole content in the gel system but, there is no systematic dependence of swelling on MA content was observed for the hydrogels obtained at low dose rate. Pore structure of the hydrogels was monitored by using scanning electron microscopy. Thermogravimetric analysis (TGA) and the rate of the thermal decomposition of P(AAm/MA/G) hydrogels has been evaluated to give a better understanding of the thermal stability of polymers, The X-ray data of P(AAm/MA/G) hydrogels was discussed to investigate some features namely the degree of ordering and crystallite size.     

PIXE investigation of in vitro release of chloramphenicol across polyvinyl alcohol/acrylamide hydrogel

Hydrogels based on polyvinyl alcohol and different amounts of acrylamide monomer were prepared by thermal cross-linking in the solid state. The hydrogels were investigated for drug delivery system applications. Chloramphenicol was adopted as a model drug to study its release behavior. Particle induced X-ray emission was utilized to study the drug release behavior across the hydrogels and a comparison study with ultraviolet measurements was performed. Fourier Transform Infrared measurements were carried out for molecular characterization. The releasing behavior of the drug exhibits a decrease and a subsequent increase in the release rate, as the acrylamide monomer increases. Characterization of the hydrogels has shown a competitive behavior between crosslinking with AAm acrylamide monomer or oligomerized version, depending on the amount added to prepare the hydrogels.     

Relaxation behaviour of radiochemically aged EPDM elastomers

EPDM-type elastomers (70% ethylene; 28% propylene; diene monomer: 2% norbornene) were characterised before and after irradiation using differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA). Three formulations were studied: pure elastomer, cross-linked elastomer with dicumyl peroxide and protected with a phenolic-type antioxidant agent. Two irradiation methods were used: γ radiation, under oxygen, at a fixed dose rate of 1 kGy/h, for total integrated doses ranging from 50 to 450 kGy and electron irradiation, under inert atmosphere, at a dose rate of 500 kGy/h, for doses of 100 and 500 kGy. For both types of irradiation, for the three EPDM formulations and for any total integrated dose, DSC and DMA show that a cross-linking phenomenon predominates. Cross-linking increases with the total integrated dose. It is also observed that cross-linking is stronger with the γ irradiation than with the electron irradiation, which confirms the influence of the oxidising atmosphere.     

层状壳聚糖水凝胶的制备与性能

通过两步低温辐射和冷冻/解冻循环相结合的方法制备聚乙烯醇/聚氧乙烯(PVA/PEO)为基层,聚乙烯醇/壳聚糖(PVA/CS)为上层抗菌功能层的层状壳聚糖水凝胶。通过对吸收剂量、电子束流、聚合物溶液浓度等的研究确定最佳制备工艺,并通过溶胀性能、力学性能、抗菌性能及红外光谱和扫描电镜表征所得层状水凝胶的结构与性能。结果表明,该方法制备的层状壳聚糖水凝胶具有明显的层状结构,层间结合紧密,壳聚糖结构未改变;层状水凝胶的溶胀性能随着壳聚糖含量增大而逐渐增大,60%CS含量平衡溶胀度达到2 200%;层状水凝胶力学强度随着壳聚糖含量增加而先增大后减小,40%CS含量下层状水凝胶从PVA/PEO凝胶的0.35MPa提高到0.47 MPa;抗菌性能测试表明层状水凝胶对大肠杆菌和金黄色葡萄球菌均具有明显的抑菌效果,抑菌性能随着壳聚糖含量的提高而增大。     

γ辐照联合热交联聚碳硅烷先驱丝热解制备高强度氮化硅陶瓷纤维

在空气气氛中采用γ射线辐照处理聚碳硅烷(PCS)先驱丝,辐照先驱丝经Ar中热交联、NH3中热解氨化、N2中高温氮化处理制备了氮化硅陶瓷纤维。研究了热交联处理对辐照先驱丝化学结构、凝胶含量、氨化陶瓷产率、抗拉强度、微观形貌及氧含量的影响。结果表明:热交联处理生成了Si—CH2—Si和Si—O—Si桥连结构,桥连结构使PCS先驱丝实现凝胶化;热交联处理不仅大幅提高了辐照PCS先驱丝的氨化陶瓷产率,还提高了热解所得氮化硅陶瓷纤维的抗拉强度,而且还降低了陶瓷纤维的氧含量;吸收剂量为1.0MGy的辐照丝经热交联处理后,其热解所得氮化硅陶瓷纤维抗拉强度达2.05GPa,氧质量分数仅为9.5%。     

γ共辐射接枝丙烯酸改善聚醚砜粉体亲水性的研究

利用γ射线共照射技术在聚醚砜（Polyethersulfone,PES）粉体上按枝了丙烯酸。研究了丙烯酸单体体积分数、接枝溶液pH值、吸收剂量、阻聚剂（Cu^2＋）浓度等对接枝率的影响规律。通过与称重法相结合,得到了利用红外光谱对接枝率进行定量分析的工作曲线。研究结果表明,当吸收剂量为25kGy、单体体积分数为30％、阻聚剂用量为0．004mol／L时,可以获得最高的接枝率。接枝溶液中盐酸的添加有利于提高接枝率。提高接枝率有助于改善PES的亲水性。     

利用60Coγ辐射聚合技术研制淀粉型农用高吸水材料

利用^60Coγ辐射聚合技术合成淀粉接枝丙烯酸盐高吸水材料。辐照剂量7kGy左右、交联剂用量0．01‰—1‰、水溶液的pH值为5—8、淀粉用量在10%—30%时制成吸水倍率可达600倍、性价比较高的农用高吸水材料。     

PNIPAM/蒙脱土复合水凝胶辐射合成与表征

采用辐射聚合方法合成了PNIPAM/蒙脱土(MMT)复合水凝胶;研究了蒙脱土对PNIPAM/MMT复合水凝胶溶胀性能和压缩性能的影响.结果表明,虽然MMT能提高复合水凝胶的初始溶胀速率和平衡溶胀率,但它不改变凝胶原有的环境响应性能和溶胀机理.PNIPAM水凝胶和PNIPAM/MMT复合水凝胶均具有温度敏感性,低临界溶解温度(LCST)均在32℃左右,溶胀机理均遵循Fickian扩散模式,即水分子的扩散成为水凝胶溶胀的决定过程.使用MMT能改善PNIPAM/MMT复合水凝胶的压缩性能;且复合水凝胶的压缩性能随MMT含量的增加而提高.     

聚二甲基硅氧烷在过氧化氢溶液中的伽玛辐射效应

研究了6%过氧化氢(H_2O_2)溶液中的聚二甲基硅氧烷(Polydimethylsiloxane,PDMS)橡胶材料的g辐射效应。首先利用拉伸实验测试了辐照前后PDMS橡胶材料力学性能的变化,然后利用甲苯平衡溶胀法,差示扫描量热分析和傅里叶变换衰减全反射红外光谱分析(Attenuated total reflection-Fourier transform infrared,ATR-FTIR)法对其辐照前后的化学结构变化进行了表征。结果表明,在H_2O_2溶液中辐照的PDMS仍发生以辐射交联为主的反应,且在相同的吸收剂量下,相较于空气中辐照的PDMS,在H_2O_2溶液中辐照的PDMS的断裂伸长率较高,弹性模量较小,交联密度较低。这可能是由于H_2O_2溶液在辐照过程中产生的氧化性活性物质能够捕获PDMS辐照生成的大分子活性自由基,从而降低了PDMS发生交联反应的概率。ATR-FTIR结果则进一步表明,随着吸收剂量的增加,PDMS表面出现一定程度的氧化,而相较于空气中辐照的样品,在H_2O_2溶液中辐照的样品表面氧化程度并未明显增强。     

4-[4-(丙烯酰氧基)苯基偶氮]苯磺酸光异构化反应及光聚合水凝胶制备

研究了水溶性偶氮苯单体4-[4-(丙烯酰氧基)苯基偶氮]苯磺酸(APABS)的光物理性质.考察了溶剂对其光异构化反应的影响,并将APABS和丙烯酸羟乙酯(HEA)组成共聚体系,在交联剂N,N-亚甲基双丙烯酰胺(MBAA)的存在下,通过光聚合方法制备水凝胶.利用扫描电子显微镜考察了聚合温度对水凝胶内部结构影响.     

辐射接枝NVP对聚L-乳酸分子量的影响

以甲醇为溶剂,采用辐射接枝法制备了聚L-乳酸(Poly-L-lactic acid,PLLA)/N-乙烯基吡咯烷酮(N-vinyl pyrrolidone,NVP)接枝共聚物。研究了醋酸(Acetic acid,HAc)浓度、单体浓度和剂量率对接枝共聚物分子量的影响,并采用傅立叶变换红外光谱(Fourier transform infrared spectrometer,FT-IR)、核磁共振氢谱(Nuclear magnetic resonance,1H-NMR)、热重分析法(Thermogravimetry analysis,TGA)对接枝共聚物进行了表征。结果表明,在相同吸收剂量下,接枝共聚物的分子量与反应介质中HAc浓度、单体浓度以及剂量率相关。当HAc浓度为0.05 mol/L,单体浓度为30%,剂量率为500 Gy/h时,接枝共聚物的分子量分别出现极大值。随着接枝率的增大,接枝共聚物的两个热失重阶段变得更为明显。