Tailored polymers, controlling synthesis

Undoubtedly the future development of polymer characterization will depend on the demand from the synthesis and application area. Requirements on more tailored properties will increase the need of more complex polymers as well as more precisely controlled synthesis, which in turn need high precision characterization. High resolution, selectivity, sensitivity, quantitativeness and speed would remain as the key words in the future development in chromatography characterization of complex polymers. 

The purpose of this review is to show how anionic polymerization techniques have successfully contributed to the synthesis of a great variety of tailor-made polymer species Homopolymers of controlled molecular weight, co-functional polymers including macromonomers, cyclic macromolecules, star-shaped polymers and model networks, block copolymers and graft copolymers. 

A promising strategy towards stable and catalyticaUy active metal colloids is their preparation inside the core of micelles formed by amphiphilic block copolymers. This strategy offers a number of advantages (i) micelles represent a nano-structured environment which can be exactly tailored by block copolymer synthesis (ii) polymers act as effective steric stabilizer ]36] (iii) metal leaching might be avoided (iv) micelles allow control over particle size, size distribution and particle solubility [37] and (v) micelles are also supposed to effect catalytic activity and selectivity [38]. 

Successive addition of monomers to the end of macromolecular initiator is the usual technique for the synthesis of tailored blockcopolymers. Anionic polymerization of pivalolactone, a-pyrrolidone— and the NCA of T-methyl-D-glutamate -2 was started from the end group of a prepolymer consisting carboxylate group or acyl lactam group or amino group. Living polymer of C-capro-lactone was expected to be formed by the initiated polymerization from polymer carbanion under kinetic controlled condition. 

Fortunately, much work has still to be developed, and especially a better knowledge of the synthesis of tailor-made polymers with well-defined architecture in order to improve the properties by a better control of the regioselectivity and of the tacticity. Even if much work on the reactivity has been extensively carried out by Tedder and Walton, methods are searched for a better orientation of the sense of addition, since most fluoroalkenes are unsymmetrical. 

A wide variety of polymeric membranes with different barrier properties is already available, many of them in various formats and with various dedicated specifications. The ongoing development in the field is very dynamic and focused on further increasing barrier selectivities (if possible at maximum transmembrane fluxes) and/ or improving membrane stability in order to broaden the applicability. This tailoring of membrane performance is done via various routes controlled macro-molecular synthesis (with a focus on functional polymeric architectures), development of advanced polymer blends or mixed-matrix materials, preparation of novel composite membranes and selective surface modification are the most important trends. Advanced functional polymer membranes such as stimuli-responsive [54] or molecularly imprinted polymer (MIP) membranes [55] are examples of the development of another dimension in that field. On that basis, it is expected that polymeric membranes will play a major role in process intensification in many different fields. 

The monomers obtained can be polymerized by themselves or copolymerized with other monomers. The co-polymerization route is effective for the synthesis of tailor-made polymer supports with precise control over functionality and other polymer characteristics, but it is laborious and requires specialized skills in polymer synthesis. 

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