Photo‐Induced Hydrogel Formation Based on g‐C3N4 Nanosheets with Self‐Cross‐Linked 3D Framework for UV Protection Application

Composite hydrogels of graphitic carbon nitride nanosheets (CNNS) and polyacrylamide (PAM) with superior UV absorption and visible transparence capabilities are reported. CNNS is employed not only as a photocatalytic initiator to trigger the polymerization of acrylamide, but also as a cross‐linker to 3D connected PAM chains via hydrogen bonds. The obtained CNNS/PAM hydrogels are highly moldable for preparing various forms, and have good mechanical properties, self‐healing ability, and photo‐stability. Furthermore, the composite hydrogels have a wide spectral range for UV absorption compared to conventional UV protective materials. Besides the complete screening of UVB (280–315 nm) in sun radiation, the CNNS/PAM hydrogel film can also filter >95% UVA radiation (315–400 nm) by regulating the coating thickness, meanwhile retaining a high visible transmittance. Therefore, the CNNS/PAM hydrogels have potential applications for shielding UV radiation. Additionally, this strategy provides a common and facile route to fabricate functional composite hydrogels via photo‐induced polymerization.     

原位螯合制备含镁聚磷酸铵的工艺研究

采用一步投料法,将磷铵、尿素和硫酸镁充分混合后粉碎,再加入反应器中原位螯合制备含镁元素的水溶性聚磷酸铵（APP）肥料。研究镁添加量、尿素/磷铵物质的量比、反应温度、反应器搅拌转速对产品聚合度及聚合度分布的影响。结果表明：当镁添加量＜5%（质量分数）时,可以促进磷铵与尿素的聚合反应,提高产品聚合度;增加尿素比例、提高反应温度,可显著提高产品聚合度;随着反应器搅拌转速增加,含镁APP产品聚合度增加,而纯APP产品聚合度降低。各实验因素对APP聚合度的影响由大到小顺序为尿素/磷铵物质的量比、反应温度、搅拌转速、镁添加量。     

Preparation of thermoresponsive poly(N-vinylcaprolactam-co-2-methoxyethyl acrylate) nanogels via inverse miniemulsion polymerization

Stimuli-responsive polymeric nanogels hold great potential in biological applications. In this work, thermoresponsive polymeric nanogels were conveniently prepared through inverse miniemulsion polymerization of two monomers with a good biocompatibility, N-vinylcaprolactam and 2-methoxyethyl acrylate. A macromolecular crosslinker, poly(ethylene glycol) dimethacrylate (PEGDMA), was used to achieve a better thermoresponsiveness, compared with low-molecular-weight crosslinkers. The prepared poly(N-vinylcaprolactam-co-2-methoxyethyl acrylate) (poly(NVCL-co-MEA)) nanogels could be well redispersed in aqueous systems, displaying a reversible thermoresponsive transition behavior. The influences of the synthesis parameters including the emulsifier content, PEGDMA content, and monomer composition on the particle properties of poly(NVCL-co-MEA) nanogels both in inverse emulsions and in aqueous dispersions were systematically investigated. Furthermore, the impacts of the monomer composition and PEGDMA content on the thermoresponsiveness of poly(NVCL-co-MEA) nanogels were also studied. Promisingly, the introduction of MEA monomeric units to the copolymer chains only slightly reduced the thermoresponsiveness of poly(NVCL-co-MEA) nanogels. This feature allows to improve the biocompatibility of polymeric nanogels by using MEA as the comonomer without need to compromise the thermoresponsiveness of nanogels. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 48237.     

PLA/PBAu嵌段共聚物合成工艺优化及降解性能

以端羟基聚乳酸（PLA）、聚己二酸-丁二醇-尿素（PBAu）为预聚物,六亚甲基二异氰酸酯（HDI）为扩链剂,制备出一种新型PLA/PBAu嵌段共聚物。研究了扩链剂用量、扩链温度以及催化剂用量对PLA/PBAu嵌段共聚物分子量的影响,确定了合成PLA/PBAu嵌段共聚物的最佳工艺条件。采用核磁共振、凝胶渗透色谱、差示扫描量热仪、扫描电镜等对共聚物薄膜结构及性能进行表征。结果表明：成功合成了PLA/PBAu嵌段共聚物,分子量可达10×10⁴,玻璃化转变温度约为41℃;并且随着PBAu含量的增加,共聚物的结晶度逐渐增加。以NaOH溶液为模拟液进行加速降解实验发现,当PBAu含量为30%时,可以显著提高嵌段共聚物的降解速率,并且通过调节PLA、PBAu预聚物的含量,可以控制嵌段共聚物的降解速率。     

聚芳双硫醚/膨胀石墨/碳纤维纳米复合材料双极板的研制

以环状芳香双硫醚低聚物(COBDS)、膨胀石墨(EG)及碳纤维(CF)为原料,通过原位开环聚合制备出纳米复合材料双极板,并研究了这种复合材料的密度、电导率、弯曲强度、微观形态等特性.结果表明,这种纳米复合材料双极板具有密度小、导电性良好、弯曲强度较高以及气密性良好等优点.     

种子乳液聚合法制备纳米SiO_2/苯丙复合乳液

采用种子乳液聚合工艺,用经硅烷偶联剂改性后的纳米SiO2原位合成了纳米SiO2/苯丙复合乳液。通过正交实验确定了最佳原料配比和聚合工艺条件,并对复合乳液性能进行了分析与表征。结果表明,当功能单体的用量为单体总量的5%、阴离子乳化剂十二烷基硫酸钠(SDS)与非离子乳化剂辛基苯基聚氧乙烯醚(OP-10)质量比为1颐1、复合乳化剂总量3%、纳米SiO2含量为单体总量的1.5%、聚合温度为80℃时,可制备具有良好综合性能的复合乳液,其涂膜耐水性、硬度、附着力等均优于普通苯丙乳液。该复合乳液乳胶粒粒度呈单峰分布,平均粒径为101nm,具有核/壳结构。     

(甲基)丙烯酸烷基酯的负离子聚合Ⅰ.聚合特点及适用的单官能团引发剂体系

综合分析了近年来有关(甲基)丙烯酸烷基酯负离子聚合所取得的成就,包括该类单体对负离子聚合的重要意义、聚合难点和解决办法.介绍了聚合特点和单官能团引发剂体系.     

有机硅阴离子氨基乳液稳定性探讨

用乳液聚合的方法合成了有机硅阴离子氨基乳液,对影响乳液稳定性的诸多因素如反应时间、温度、中和剂及乳液非挥发物含量在不同存放条例下随时间的变化值等进行了探讨。结果表明,在80℃下反应6h可获得稳定的阴离子乳液;在酸性条件下存放,该乳液的非挥发物含量随时间逐渐递增,约30天后稳定;用20%三乙醇胺溶液中和后存放,乳液的非挥发物含量在前10天内逐渐增加,然后趋于稳定。     

微乳液聚合研究进展

概述了微乳液的性质,并对国内外正相微乳液聚合、反相微乳液聚合、双连续微乳液聚合的研究进行了简要综述。     

聚丙烯酸钠高吸水性树脂的制备及性能研究

以环己烷为连续相 ,Span - 6 0为悬浮稳定剂 ,过硫酸钾为引发剂 ,N ,N′ 亚甲基双丙烯酰胺为交联剂 ,对反相悬浮聚合制备聚丙烯酸钠高吸水性树脂进行了研究。结果表明 ,影响合成树脂吸水率最主要的因素是交联剂质量分数 ,当交联剂质量分数为 0 .0 15 %时合成树脂的吸水率出现极大值 ,而且当反应温度控制在 6 5℃、引发剂质量分数为 0 .18%时所得树脂的吸水率可达 5 0 0g/g。对合成树脂吸水、保水性能的进一步测试发现 ,树脂在吸水的初始阶段吸水速率较快 ,随着吸水时间的延长逐步下降 ,当树脂吸水饱和后水分损失则很慢 ,在 84℃下 2 .5h仅损失 17%。