Molecular weight by Gel permeation chromatography

Polymer films were dissolved in appropriate solvents for determination of molecular weight by gel permeation chromatography (GPC). GPC molecular weights are referenced to polystyrene standards, which are suitable for determining relative changes in molecular weights. 

The prepolymer used in later syntheses was based on monomers with x=2. The number average molecular weight by gel permeation chromatography (GPC) using polystyrene reference was 20,000 and by NMR was 18,000. ( 9) TTiis prepolymer is designated 7-Fox20K. MDI (Kodak) was distilled under reduced pressure and stored in refrigerator before use. IPDI, BDM, tetrahydrofuran (THF), N,N-dimethyl-acetamide (DMAc) and methanol were purchased from Aldrich and used as received. 

This chapter contains one of the more diverse assortments of topics of any chapter in the volume. In it we discuss the viscosity of polymer solutions, especially the intrinsic viscosity the diffusion and sedimentation behavior of polymers, including the equilibrium between the two and the analysis of polymers by gel permeation chromatography (GPC). At first glance these seem to be rather unrelated topics, but features they all share are a dependence on the spatial extension of the molecules in solution and applicability to molecular weight determination. 

Fig. 3. Molecular weight distribution curves as determined by gel-permeation chromatography. A represents i9f2v (9-phthahc resins B, highest molecular...

In Table 1 some of the properties of raw synthetic hj -l,4-polyisoprene (Goodyear s Natsyn) and natural mbber (Hevea) are presented along with references that contain additional thermal, optical, electrical, and mechanical property data. Some properties of synthetic /n j -l,4-polyisoprene (Kuraray TP-301) are also given. Molecular weights and mol wt distribution are determined by gel-permeation chromatography (gpc) (11). 

In the preparation of commercial DGEBPA, an excess of epichl orohydrin is used in order to minimize polymeriza tion of the reactants to higher molecular-weight species. Nevertheless, the typical viscous final product usually contains ca 80% by weight of the monomeric (n = 0) DGEBPA as deterrnined by gel-permeation chromatography (gpc). The manufacture of Hquid epoxy resins in a batch process has been described in some detail (9). 

The packing material for liquid chromatography is produced from styrene and divinylbenzene dissolved in 50 to 300% by weight of organic solvent to both monomers. The constitution of divinylbenzene in the monomer mixture is not less than 60% by weight. In gel-permeation chromatography, the exclusive molecular weight is not less than 1 X 10 in terms of standard polystyrene (79). 

Measurement by gel permeation chromatography in 0.2 M phosphate buffer pH 7.0 with polystyrenesulfate or polyethylene glycols ([5] in the case of aureobasidium sp. A-91) as molecular weight standards. Data processing as de.scribed in Ref. [II]. 

Nonionic surfactants, including EO-PO block copolymers, may be readily separated from anionic surfactants by a simple batch ion exchange method [21] analytical separation of EO-PO copolymers from other nonionic surfactants is possible by thin-layer chromatography (TLC) [22,23] and paper chromatography [24], and EO-PO copolymers may themselves be separated into narrow molecular weight fractions on a preparative scale by gel permeation chromatography (GPC) [25]. 

In a very recent study, it has been demonstrated116 that zinc 5,15-bis(3,5-di-tert-butylphenyl)-porphyrin (13) without any activating halogen atoms at the chromophore can be directly linked in a very simple oxidative coupling reaction with silver(I) hexafluorophosphate to a mixture of porphyrin dimers, trimers and tetramers. The separation of the product mixture was achieved by gel-permeation chromatography based on the molecular weights of the oligomers. The dimer when re-exposed to the same reaction conditions yielded 25% of the tetramer.116... 

By gel permeation chromatography. Molecular weight prior to compounding was 97,100 3800. 

Terry, S. L. and Rodriguez, F., Measurement of functional group and molecular weight interrelation by gel-permeation chromatography/infra-red, ].Polym. Sci. 21C, 191, 1968. 

Mori, S., Determination of the composition and molecular-weight distribution of a poly(vinyl chloride-vinyl acetate) co-polymer by gel permeation chromatography and infrared spectroscopy, ]. Chromatogr., 157, 75, 1978. 

Molecular weights were measured by gel permeation chromatography on a Perkin-Elmer Series 10 Liquid Chromatograph using tetrahydro-furan as solvent and refractive index as the detection mode. Standards were polystyrene, and reported molecular weights for the poly-siloxanes do not include a correction. 

---