From new initiating systems for atom transfer radical polymerization to block copolymers

Atom transfer radical polymerization (ATRP) is an especially powerful controlled radical polymerization (CRP) technique which provides control over topology, composition, microstructure, and functionality of polymeric materials. Block copolymers prepared by ATRP have a bright future as new polymeric materials for many different applications. This is because properties of block copolymers may be predicted and designed for a particular application by choosing suitable building blocks (monomers). ATRP was proven to be very successful in the preparation of many well-defined block copolymers (Chapter 1).; However, despite the potential commercial application of numerous block copolymers synthesized by the ATRP process, their production on an industrial scale has been rather limited. It can be attributed mostly to special handling procedures which are required in order to remove all oxygen and oxidants from the polymerization systems and high catalyst concentrations required by normal ATRP process, which increases the expenses associated with catalyst removal from the final polymer (Chapter 1).; The main goal of the research presented here is to alleviate these problems, simplify preparation of block copolymers and as a result bring the industrial application of ATRP closer to reality. For this purpose new initiating systems for ATRP were developed. In Chapter 2, technique based on activator generated by electron transfer for ATRP (AGET ATRP) is described. The discovery of this method enabled preparation of pure block copolymers starting from an oxidatively stable catalyst in the presence of reducing agent that is unable to initiate new chains. This is in contrast to previously used simultaneous reveres and normal initiation (SR&NI) ATRP, where the synthesis of pure blocks was not possible due to the use of radical initiator.; Furthermore, new initiating systems were discovered which allow a decrease in the amount of catalyst by more than three orders of magnitude, so that removal or recycling of the ATRP catalyst would be unwarranted for most industrial applications. A new method based on activators regenerated by electron transfer (ARGET) is described in Chapter 3, and a second one based on initiators for continuous activator regeneration (ICAR) is presented in Chapter 4. Lowering the concentration of the catalysts in these two techniques not only led to a 'greener' polymerization process, but opened the door for new material synthesis with ATRP. Reduced catalyst-based side reactions allowed synthesis of high molecular weight polymers and polymers with high chain-end functionality, which further simplified preparation of block copolymers (Chapter 5). The combination of new methods with normal ATRP were used in the preparation of block copolymers for special application such as polymeric coating for a coronary stent used in angioplasty (Chapter 6). In the last part of the thesis (Chapter 7), ATRP was combined with ring opening polymerization (ROP) in order to further extend the spectrum of properties of block copolymers.