Gradient copolymers

Hotnopolytners Block Copolymers Statistical Copolymers Gradient Copolymers Graft Copolymers... 

Xu C, Wu T, Batteas JD, Drain CM, Beers KL, Easolka MJ (2006) Surface-grafted block copolymer gradients effect of block length on solvent response. Appl Surf Sci 252 2529-2534... 

Fig. 12 Surface expression of block segments in block copolymer gradient libraries after treatment to two solvents. See text for details a illustration of surface expression of PnBMA black) and PDMAEMA blue) block copolymer brush segments after water and hexane treatments b water contact angle data from three PnBMA-b-PDMAEMA block copolymer gradient libraries after hexane filled symbols) and water open symbols) treatments. (Derived from [58] with permission)...

The ability to synthesize a wide variety of architectures such as telechelic, block copolymers, graft copolymers, gradient copolymers, nanogels, stars, and dendritic structures. " - ... 

Contrary to statistical and block copolymers, gradient copolymers exhibit a composition gradient along their chain. The properties of gradient copolymers are expected to be intermediate between those of block and statistical copolymers. In particular, their kinetics of aggregation and exchange can be faster than in the case of block... 

The method has severe limitations for systems where gradients on near-atomic scale are important (as in the protein folding process or in bilayer membranes that contain only two molecules in a separated phase), but is extremely powerful for (co)polymer mixtures and solutions [147, 148, 149]. As an example Fig. 6 gives a snapshot in the process of self-organisation of a polypropylene oxide-ethylene oxide copolymer PL64 in aqueous solution on its way from a completely homogeneous initial distribution to a hexagonal structure. 

Copolymers produced by living polymerization processes differ from those produced by conventional polymerization in one important aspect. Living polymerization processes produce gradient or tapered copolymers. Such copolymers are known from anionic living polymerization. 

Table 9.22 Statistical/Gradient Copolymers Synthesized by RAFT Polymerization...

Seymour and coworkers (27,28,29,30) actually used these composition gradients to prepare block copolymers by swelling particles containing occluded (i.e., living) macroradicals with a second monomer. Such block copolymers were prepared from occluded vinylacetate, methyl methacrylate, and acrylonitrile macroradicals, and the yield of block copolymers was studied as a function of the solubility and rate of diffusion of the swelling monomer in the particles. 

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