树枝状大分子
1.Dendrimers are repeatedly branched molecules. The huge number of papers on dendritic architectures such as dendrimers, dendronized, hyperbranched and brush-polymers has generated a vast variety of inconsistent terms and definitions making a clear and concise unfolding of this topic highly difficult. The purpose of this section is to provide the vocabulary required for the description of chemical and physical phenomena as well as application aspects associated with the research in the area of dendritic molecules.
Dendritic molecules are repeatedly branched species that are characterized by their structure perfection. The latter is based on the evaluation of both symmetry and polydispersity. The area of dendritic molecules can roughly be divided into the low-molecular weight and the high-molecular weight species. The first category includes dendrimers and dendrons whereas the second encompasses dendronized polymers, hyperbranched polymers, and brush-polymers (also called bottle-brushes).
The name comes from the Greek "δενδρον"/dendron, meaning "tree". Synonymous terms are arborols and cascade-molecules. Dendrimer is an internationally accepted term. Dendrimers and dendrons are repeatedly branched, monodisperse, and usually highly symmetric compounds. There is no apparent difference in defining dendrimer and dendron. A dendron usually contains a single chemically addressable group that is called the focal point. Because of the lack of the molar mass distribution high-molar-mass dendrimers and dendrons are macromolecules but not polymers.
The first dendrimers were synthesized divergently by Vögtle in 1978[1], by Denkewalter and coworkers at Allied Corporation as polylysine dendrimers in 1981[2], by Tomalia at Dow Chemical in 1983[3] and in 1985[4], and by Newkome in 1985[5]. In 1990 a convergent synthesis was introduced by Mingjun Liu[6]. Dendrimers then experienced an explosion of scientific interest because of their unique molecular architecture (Fig 1). This resulted in over 5,000 scientific papers and patents published by the end of 2005.
【ref.1 http://en.wikipedia.org/wiki/Dendrimer】
2.“dendrimer”这个词来自希腊的“dendros”，意思是树和枝，树上的分枝长到一定长度后又分成两个分枝，如此重复进行，直到长得如此稠密以致于长成象球形一样的树丛。在dendrimer中，分枝是内部连结的高分子聚合键，每一个键又会产生新键，全部会向一个焦点聚合或向一个核聚合。
在dendrimer上形成大量键端球形突起物，象毛线球上的绒毛。在合成过程中，能设计这些键端去执行特殊的化学功能，例如，键端可带电，其目的是完全发挥dendrimer的高分子电解质的功能。另一个特点，在合成过程中，也能控制dendrimer外部尺寸和内部的构。这使得有可能创造与外部不同性质的内腔和通道，并打开dendrimer作为载体或作为受邀分子晶核的大门。在这一能力中，dendrimer除了为纳米技术建造纳米块外，还起催化作用。【ref.2 http://blog.mdbchina.com/hahalu/post_180105/】