纳米材料掺杂聚合物整体柱的构筑及在前处理领域的应用

Fabrication of nanomaterials incorporated polymericmonoliths and application in sample pretreatment

聚合物整体柱是由单体、交联剂、引发剂和致孔剂在模具中通过原位聚合而成的棒状整体。与传统的填充式固相萃取柱相比,聚合物整体柱吸附剂凭借制备简单、柱压低、传质快及pH使用范围宽泛等优点已广泛应用于食品分析、生物医药和环境卫生等领域的前处理中。然而,通常由于聚合方式难以控制,聚合物整体柱在制备过程中容易产生颗粒堆积、孔道不均匀从而导致孔隙率低和比表面积有限等问题。近年来,将纳米材料掺杂至聚合物整体柱以获得有序结构分布、良好吸附效率以及优越选择性能的新型吸附剂成为研究热点。纳米材料种类繁多,尺寸小,利用其表面丰富的活性基团、作用位点和超大的比表面积等优势,通过简单掺杂、共聚合和原位修饰等方法合成纳米掺杂聚合物整体柱,不仅能够改善其微观结构、柱床机械强度和稳定性,同时可以显著提高掺杂聚合物整体柱吸附剂的萃取性能和选择性。该文综述了碳材料、金属和金属氧化物、金属有机骨架、共价有机骨架和无机纳米粒子等不同纳米材料掺杂的聚合物整体柱、常用的构筑方法以及该类吸附剂在固相萃取、固相微萃取、搅拌棒吸附萃取和在线固相萃取等样品前处理领域的应用,并展望这一研究的发展趋势和应用前景,以期为前处理领域的研究提供参考。

Polymeric monolithic columns are fabricated by in situ polymerization of the corresponding monomer,crosslinkers,porogenic solvents and radical initiators within a mold.Compared with the conventional packed solid phase extraction adsorbents,polymeric monolithic columns with a continuous porous structure process distinctive advantages of rapid mass transfer and excellent permeability,which facilitates the extraction of trace amounts of the target from the matrix even at high flow velocities.Besides,these materials can be easily fabricated in situ within various cartridges,avoiding a further packing step associated with packed particulate adsorbents.Additionally,the abundant monomer availability,flexible porous structure,and wide applicable pH range make monoliths versatile for use in separation science.Thus,polymeric monolithic columns have been increasingly applied as efficient and promising extraction media for sample pretreatment food,pharmaceutical,biological and environmental analyses.However,these materials usually have the difficulty in morphology control and their interconnected porous micro-globular structure,which may result in low porosity,limited specific surface area and poor efficiency.In addition,polymeric monoliths suffer from the swelling in organic solvents,thus decreasing the service life and precision while increasing the cost consumption.Recently,the development of nanomaterial-incorporated polymeric monoliths with an improved ordered structure,enhanced adsorption efficiency and outstanding selectivity has attracted considerable attention.Nanoparticles are considered as particulates within the size range of 1-100 nm in at least one dimension,which endows them with unique optical,electrical and magnetic properties.These materials have a large surface area,excellent thermal and chemical stabilities,remarkable versatility,as well as a wide variety of active functional groups on their surface.With the aim of exploiting these advantages,researchers have shown great interest in applying nanomaterial-incorporated polymeric monoliths to separation science.Accordingly,significant progress has been achieved in this field.Nanomaterials can be entrapped via the direct synthesis of a polymerization solution that contains well dispersed nanomaterials in porogens.In addition,nanoparticles can be incorporated into the monolithic matrix by copolymerization and post-polymerization modification via specific interactions.Therefore,nanomaterial-incorporated polymeric monoliths combined the different shapes,chemical properties,and physical properties of the polymers with those of the nanoparticles.The presence of nanoparticles can improve the structural rigidity as well as the thermal and chemical stabilities of monolithic adsorbents.Besides,nanoparticles are capable of increasing the specific surface area and providing multiple active sites,which leads to enhanced extraction performance and selectivity of polymeric monolithic materials.In recent years,diverse types of nanomaterials,such as carbonaceous nanoparticles,metallic materials and metal oxides,metal-organic frameworks,covalent organic frameworks and inorganic nanoparticles have been extensively explored as hybrid adsorbents in the modes of solid phase extraction,solid phase microextraction,stir bar sorption extraction and on-line solid phase extraction.This review specifically summarizes the fabrication methods for nanomaterial incorporated polymeric monoliths and their application to the field of sample pretreatment.The existing challenges and future possible perspectives in the field are also discussed.