Tailoring, diblock copolymers

Finally, it has been stated that this new toughening technique can be safely extended to other fragile plastics, such as PVC and PS (38). This observation supports that a properly tailored diblock copolymer can help in generating materials with highly improved properties. Engineering polymer blends... 

The reported examples convincingly support that using a purposely tailored diblock copolymer is a powerful tool of generating new, or at least improved, multiphase polymeric materials. Quite interestingly, the interfacial activity of diblock copolymers is not exclusively confined to immiscible polymer blends but it can be fruitfully extended to dispersions of fine solid particles in either a liquid phase or a polymeric matrix, as illustrated hereafter. 

Dispersion of solid particles in a polymeric matrix is another target that can be reached successfully using a purposely tailored diblock copolymer. 

Finally, the main interest in CMRC hes in the potential to prepare novel materials, as illustrated by the synthesis of highly symmetrical ABA triblock copolymers from tailored diblock precursors. Following this convergent approach, PVAc-h-PAN-h-PVAc and PVAc-h-PNVP-b-PVAc triblocks were synthesized by CMRC from the parent PVAc-h-PAN-[Co] and PVAc-h-PNVP-[Co] diblocks [58, 59]. The specific midfunctional groups (alcohols) effectively promote the coupling reaction by the same mechanism [60]. 

Thermodynamically stable, bicontinuous microemulsions have recently been shown to be obtainable in symmetric ternary blends of two homopolymers and a diblock copolymer by formulating alloys with compositions near mean-field isotropic Lifshitz points. In the present paper, it is argued that practical apphcation of this design criterion could require use of homopolymers of unequal molec.wts. and block copolymers of different structure. The existence of, and explicit location of, mean-field isotropic Lifshitz points in ternary blends with homopolymer molec.wt. asymmetry and either AB diblock or ABA triblock copolymer structures were demonstrated. These calculations significantly expanded the parameter space for observing bicontinuous miCToemulsions and allowed for more flexibility in tailoring melt rheological properties and solid-state mechanical properties. 29 refs. 

Markedly, surface-initiated ATRP provides the opportunity to use a variety of functional monomers, to tailor the composition and thickness of the brushes, and to prepare multiple functional surfaces. For example, Zhang et al. prepared poly(methyl methacrylate) (PMMA), poly(acrylamide) (PAAM), and their diblock copolymer (PMMA/PAAM) on the surface of PET film by surface-initiated ATRP [59]. The results indicated that the surface properties of PET film were greatly improved by grafted polymer, the surface of PET film modified by PAAM was hydrophilic, and the surface of PET film modified by diblock copolymer was amphiphilic. This kind of modified PET film may be applied as biocompatible materials, amphiphilic functional film, or conductive film. 

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