Composition, copolymer, function

The structural complexity of synthetic polymers can be described using the concept of molecular heterogeneity (see Fig. 1) meaning the different aspects of molar mass distribution (MMD), distribution in chemical composition (CCD), functionality type distribution (FTD) and molecular architecture distribution (MAD). They can be superimposed one on another, i.e. bifunctional molecules can be linear or branched, linear molecules can be mono- or bifunctional, copolymers can be block or graft copolymers, etc. In order to characterize complex polymers it is necessary to know the molar mass distribution within each type of heterogeneity. 

On the basis of a systematic study of the emulsifying effect of block copolymers in PS-PI and in polystyrene-poly (methyl methacrylate) (PS-PMM) polyblends (3), it was possible to represent schematically the appearance of the films for different blend compositions as functions of molecular weight and composition of the block copolymer (Cop), as well as of molecular weight of the homopolymers (see Figure 2). Thus in a polyblend containing PS and PI of practically the same molecular weight — M2), the best... 

Molecular weight distribution information obtained by size-exclusion chromatography on its own is insufficient to characterize the properties of complex polymers, such as copolymers and block and graft polymers [23,514,524]. For these polymers the chemical composition and functionality type distributions are equally important. A major obstacle to the characterization of these materials is that their molecular properties are present as joint distributions. Unlike the mass distribution the composition and functionality distributions can only be determined by separation methods that employ interactions with the stationary phase. To fully characterize a complex polymer it is not unusual to use manual or automated tandem techniques where the sample is fractionated according to its chemical or end group composition for subsequent further separation by size-exclusion chromatography to establish their mass distribution. Chromatographic methods may also be combined with spectroscopic methods to determine microstructural information. 

Direct measurement of absorbance of different functional groups, measurement of end groups, analysis of specific interactions and monomer concentration can all be used to monitor quantitative copolymer composition. Copolymer composition is determined by using the absorbance intensity ratio of monomer specific vibrational modes of vibration. A number of copolymer systems have been investigated ... 

Composition and Functionality I Controlled Composition Statistical, Gradient, and Alternating Copolymers... 

Composition and Functionality Well-Definetl Block Copolymers... 

Composition and Functionality I Well-Defined Block Copolymers 459... 

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