Characterization of copolymers

The characterization of copolymers must distinguish copolymers from polymer blends and the various types of copolymers from each other (97,98). In addition, the exact molecular stmcture, architecture, purity, supermolecular stmcture, and sequence distribution must be determined. 

High-performance size exclusion chromatography is used for the characterization of copolymers, as well as for biopolymers (3). The packings for analyses of water-soluble polymers mainly consist of 5- to 10-/Am particles derived from deactivated silica or hydrophilic polymeric supports. For the investigation of organosoluble polymers, cross-linked polystyrene beads are still the column packing of choice. 

NMR spectroscopy has made possible the characterization of copolymers in terms of their monomer sequence distribution. The area has been reviewed by Randall,100 Bovey,139 Tonelli,101 Hatada140 and others. Information on monomer sequence distribution is substantially more powerful than simple composition data with respect to model discrimination,25,49 Although many authors have used the distribution of triad fractions to confirm the adequacy or otherwise of various models, only a few25 58,141 have used dyad or triad fractions to calculate reactivity ratios directly. 

A careful characterization of copolymers is quite time consuming and a combination of methods as discussed in Section 6.1 might be considered. In practice the situation is often complicated by an amphiphilic character of the copolymers, which leads additionally to micelle formation. 

A combination of infrared spectroscopy with size exclusion chromatography has a wide application range in the characterization of copolymers, adhesives, impurity profiling in polymers and branching in polyolefines [60-65]. Commonly, the solvent used as a mobile phase absorbs strongly in the... 

In the characterization of copolymers one distinguishes between qualitative analysis, designed to test whether the material is a genuine copolymer or only a physical mixture of homopolymers, and quantitative analysis of the weight fraction of the incorporated comonomers. 

G.R. Meira, J.R. Vega, Characterization of copolymers by size exclusion chromatography, in Handbook of Size Exclusion Chromatography and RelatedTechniques, vol. 91 (Chromatographic Sciences Series), C.-s. Wu, ed., Marcel Dekker, Inc., New York, 2004, p. 139. 

Table 15. Preparation and characterization of copolymers of bismaleimide blend ...

It is the combination of different techniques which is important in the characterization of copolymers for their different heterogeneities. ... 

Glockner, G., van den Berg, J. H. M., Meijerink, N. L., Scholte, T. G. Characterization of copolymers chromatographic cross-fractionation analysis of styrene-acrylonitrile copolymers , in Kleintjens, L., Lemstra, P. (ed) Integration of Fundamental Polymer Science and Technology , Elsevier Applied Science Publ., Barking, UK (1986), p. 85... 

This review demonstrated that research on diallyldimethylammoium chloride and its polymers have contributed to the general understanding of the polymerization of ionic monomers, the development of methods for the molecular characterization possibilities of cationic polyelectrolytes, and the understanding regarding polyelectrolyte behavior. However, in comparison to the industrial importance of diallyldimethylammonium chloride polymers, the level of fundamental knowledge is far from adequate. In particular, copolymerization processes with monomers other than acrylamide, the characterization of copolymers related to their chain architecture and charge distribution, the dependence of... 

Physical Methods for the Characterization of Copolymers Produced from Epoxides or Oxetane and Carbon Dioxide... 

In this chapter, some of the essential aspects of the synthesis and characterization of copolymers derived from the coupling of C02 with various monomers, namely, epoxides, oxetanes, and aziridines, have been reviewed. In addition, the use of carbon disulfide as a resource for copolymer production was introduced, and the present understanding of the mechanistic aspects of processes involving cyclic ethers and C02 catalyzed by well-defined metal systems has been emphasized. This knowledge has led to the development of catalytic systems capable of controlling not only the product selectivity but also the regio- and stereoregularities of the resultant copolymers. 

Sometimes in practice, we may have no choice of solvent for a given polymer. For example, poly(l,4-phenyleneterephthalamide) (PPTA or Kevlar) is only soluble in very strong acids which are viscous. In such cases, ultracentrifugation instead of filtration has to be used to remove dust particles from the solution [14-16,25]. As for copolymers, the selection of proper solvents is even more difficult, because at least two solvents which satisfy the above mentioned three criteria are needed. For this reason, reported characterization of copolymers is quite limited [26-29]. 

The first volume concentrates on separation techniques. H. Pasch summarizes the recent successes of multi-dimensional chromatography in the characterization of copolymers. Both, chain length distribution and the compositional heterogeneity of copolymers are accessible. Capillary electrophoresis is widely and successfully utilized for the characterization of biopolymers, particular of DNA. It is only recently that the technique has been applied to the characterization of water soluble synthetic macromolecules. This contribution of Grosche and Engelhardt focuses on the analysis of polyelectrolytes by capillary electophore-sis. The last contribution of the first volume by Coelfen and Antonietti summarizes the achievements and pitfalls of field flow fractionation techniques. The major drawbacks in the instrumentation have been overcome in recentyears and the triple F techniques are currently advancing to a powerful competitor to size exclusion chromatography. 

Glukhikh V, Graillat C, Pichot C (1987) Inverse emulsion polymerization of acrylamide. II. Synthesis and characterization of copolymers with methacrylic acid. J Polym Sci Polym Chem Ed 25(4) 1127-1161... 

Blomquist, B., Helgee, B., Maurer, F.H.(2001) Synthesis and characterization of copolymers of methyl methacrylate and ll-(4-ethoxyazobenzene -4 -oxy) undecyl methacrylate . Marcromolecules Chem. Phys. 202,2742. 

Garcia-Rubio LH, MacGregor JF and Hamielec AE (1981) Size exclusion chromatography-characterization of copolymers. Polym Prepr Am Chem Soc, Div Polym Chem) 22(l) 292-3. 

Gradient high-performance liquid chromatography (HPLC) has been useful for the characterization of copolymers (14-19). In such experiments, careful choice of separation conditions is a conditio sine qua non. Otherwise, low resolution for the polymeric sample will obstruct the separation. However, the separation in HPLC, dominated by enthalpic interactions, perfectly complements the entropic nature of the SEC retention mechanism in the characterization of complex polymer formulations. 

Multiple detection applied to the SEC characterization of copolymers is attractive because it yields both CCD and MWD information. A dual detection system based on two concentration detectors, for example, RI and UV, is useful where narrow standards of the homopolymers are available and where both homopolymers obey universal calibration. However, in other copolymer systems the addition of a third detector, LALLS, can offer the advantage of on-line determination of molecular weight for each eluting species. The triple detection approach gave similar values to the dual detector approach for a model copolymer system (PS-PMMA) studied. It was also applicable to a more difficult copolymer system (PS-PEO), although it appeared that where one homopolymer was present in very small quantities, an average p value gave more consistent results than correction for pi across the distribution. 

R.A. (2007) Lipase-catalyzed copolymerization of co-pentadecalactone with p-dioxanone and characterization of copolymer thermal and crystalline properties. Biomacromolecules, 8 (7), 2262-2269. 

Scholsky, K. M., O Connor, C. S. Weiss, and V. J. Krukonis, 1987. Characterization of copolymers fractionated using supercritical fluids, J. Appl. Polym. Set. 33 2925. Schroeder, E. and K. F. Arndt. 1976a. Loslich Keitsverhalten von Makromolekiilen in Komprimierten gasen. I. Einfiihrung und MeCmethodik. Fa.serfor.schung und Tex-tiletechnik 27 135-139. 

The copolymerization of TXN and St was analysed in a number of papers 150,151 in terms of conventional reactivity ratios without paying attention to the proper characterization of copolymers and other factors discussed in this volume (cf. Chap. 15). Some additional information comes from the studies of similar systems, i.e. DXL-St copolymerization 152). Also in this case product characterization mainly involved solubility studies, although Yamashita et al. claimed that 1H-NMR spectra confirmed that the product is indeed a true copolymer. This claim was based on a rather limited analysis of H-NMR spectra, however, and was not confirmed by analysis of spectra of related models. Copolymerization conditions were as follows [DXL]0 = 0.7 - 3.7 mol l [St]0 = 4.5 — 2.7 mol l-1, [BF3 OEt2] = 2,5 10-2 mol 1 1, 25 °C, in toluene. After 2-8hrs, from 2% to 9% product with fr ] = 0.12 — 0.32 dl g-1 (viscosity determination conditions not specified) was obtained. 

Elemental composition and content of some specific elements is an important analytical tool for polymer characterization, mainly for the characterization of copolymers and polymer blends and the determination of molecular weight of homopolymers [2, 3]. 

Ali N, Suhaimi NS (2009) Performance evaluation of locally fabricated asymmetric nanofiltration membrane for Batik industry effluent. World Appl Sci J 5 46-52 Alias Z, Tan IKP (2005) Isolation of palm oil-utilising, polyhydroxyalkanoate (PHA)-producing bacteria by an enrichment technique. Bioresour Technol 96 1229-1234 Allen AD, Anderson WA, Ayorinde FO, Eribo BE (2010) Biosynthesis and characterization of copolymer poly(3HB-co-3HV) from saponified Jatropha curcas oil by Pseudomonas oleovorans. J Ind Microbiol Biotechnol 37 849-856 Allen AD, Anderson WA, Ayorinde F, Eribo BE (2011) Isolation and characterization of an extracellular thermoalkanophilic P(3HB-co-3HV) depolymerase from Streptomyces sp. INI. Int Biodeterior Biodegrad 65 777-785... 

Another more reeent approach to the chromatographic characterization of copolymers is the eoneept of invisibility , which assumes that chromatographic conditions exist under whieh heteropolymers may be separated according to the... 

In order to compare the results of critical chromatography with results of an independent method, SEC with coupled density (D) and refractive index (RI) detection was used, which has been shown to be very useful for the characterization of copolymers with respect to their chemical composition [39,40]. The MMD curve for one of the block copolymers and the mass distribution curves of the components are shown in Fig. 18. From these the overall chemical composition may be calculated. An excellent agreement between the results of critical chromatography and the SEC experiments was obtained. 

In Section 2.4 we consider copolymers. The determination, by MS techniques, of various quantities (such as copolymer composition, sequence distribution, composition heterogeneity, reactivity ratios, and bivariate distribution of chain compositions and chain lengths) are of major interest for the characterization of copolymers. 

Montaudo, G., Scamporrino, E., and Vitalini, D., Characterization of Copolymer Sequences by FAB-MS. I. Identification of Oligomers Produced in the Hydrolysis and Photolysis of Random Copolyamides Photolabile Units in the Main Chain, Macromolecules, 22, 623 (1989). 

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