RAFT 聚合技术
RAFT 下腹部隐痛的原因聚合技术首先由当值Rizzardo 等在第37 届国际高分子大会上公布。该过程是一个可逆反应, 称为可逆加成- 裂解链转移过程(Reversible Addition-Fragmentation chain Transfer),也就是RAFT。RAFT体系适用的单体种类多富有哲理的句子,聚合所需温度较低,可制备较高分子量的窄分布聚合物。因此,具有广阔的应用前景。
RAFT technology团结的句子
CSIRO and DuPont have developed an innovative technology known as RAFT (for Reversible Addition Fragmentation chain Transfer), which allows for the synthesis of specially designed polymeric materials with enhanced properties. CSIRO has licend this technology to Strem to make available to you for rearch purpos.
RAFT technology is a sophisticated form of controlled free radical polymerization. Often known as 'living polymerization' (it can be stopped and restarted at anytime) this technology enables the synthesis of tailored polymers with unprecedented control over composition and architecture.
Polymers may be synthesized more readily, using RAFT technology,
• With predetermined molecular weight and narrow molecular weight distributions over a wide range of monomers and reaction
conditions,
• With reactive terminal groups that can be purpoly manipulated, including further polymerization,鞋子用英语怎么说
• With complex architecture, including A B diblock, A B A triblock, graft, star; gradient and branched polymers (e Fig I),
• That are bad on scaleable manufacturing process utilizing conventional processing equipment.
RAFT technology can be ud with a wide range of monomers and monomer mixtures, and can be ud in all modes of free radical polymerization, including solution, emulsion and suspension polymerizations. This allows for an unlimited array of tailored compositions and complex architectures under standard conditions.
The RAFT process
Implementing the RAFT process can be as simple as introducing a suitable chain transfer agent, known as a RAFT Agent (e Fig 2), into conventional free radical polymerization, while employing plant and equipment. The RAFT Agents allow for the preparation of polymers with low polydispersity, well-defined microstructure and predetermined molecular weight.
As the newly formed polymer is terminated by an active RAFT group, thereby rendering it a RAFT Agent in its own right, it is capolymerization reactions or can be subjected to othe
r chemical manipulations (e Fig 3). Incorporation of the RAFT Agent in the need for its removal, thereby simplifying the isolation and friendly process that does not require expensive and contaminat Further detailed information on RAFT technology may be found in the following references:
• Living Free-Radical Polymerization by Reversible Addition-Fragmentation Chain Transfer:The RAFT Process.J. Chiefari, et al, Macromolecules, 1998,31,5559-5562.
• Living Radical Polymerization by the RAFT Process. G. Moad, E. Rizzardo, S. H.Thang, Aust. J. Chem. 2005,58, 379-410.
• Living Radical Polymerization by the RAFT Process -A First Update.G. Moad, E. Rizzardo, S. H.Thang, Aust. J. Chem. 2006,59, 669-692.
*Content reproduced with permission of CSIRO.
The RAFT process is typically started by a parate,commercially available, free radical initiator. The RAFT Agent is rapidly incorporated into the growing polymer and facilitates further growth of the polymer by incorporating monomer, one unit at a time. Incorporation of the RAFT Agent into the final polymer results in a cleaner and more versatile product.无所不有
Overall, RAFT polymerization results in:
•Polymers with contro lled molecular weight
•Narrow distribution of molecular weight, i.e. low polydispersity
青春期心理健康•The ability to incorporate, in a defined quence, one or more type of monomers in the polymer chain
•The RAFT group being retained in the final polymer, and仓鼠能吃什么
•The opportunity for further chemical manipulation of the RAFT group, including further polymerization or removal
