Molecular weight determination by gel permeation chromatography

The dextran used in this work was the commercially available Dextran T-40 (Farmacia), produced by Leuconostoc mesenteroides B512 species. The average molecular weight determined by gel permeation chromatography was = 13,000, = 36,000. Dex-... 

Spatorico, A.L. and Coulter, B. (1973) Molecular-weight determinations by gel-permeation chromatography and viscometry. Journal of Polymer Science Part B-Polymer Physics, 11,1139-1150. 

Solubility tests carried out on the polymers revealed that all the LC poly (azomethine esters) were insoluble in common organic solvents such as chloroform, THF and acetone. This leads to the difficulty in their molecular weight determination by gel permeation chromatography (GPC). The inherent viscosities (r ii ) of the polymers 3 (a-d) were as given in Table 12.1. The low inherent viscosities may be attributed to the poor solubility of the polymers in the polymerization solution. Precipitate was also formed during the polymerization which hinders further propagation of the polymer chain and thus leads to lower molecular weight. 

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). 

Molecular Weight. Molecular weights were determined by gel permeation chromatography (GPC) on a chromatographic system consisting of a Perkin-Elmer Model 410 pump, a Waters Model 410 RI detector, and a Perkin-Elmer Model 3600... 

Molecular weights of the copolymers were determined by gel permeation chromatography (GPC) with four p-styragel (Haters) columns calibrated using polystyrene standards. Chloroform was used as the eluate at a flow rate 1.5 ml/min. An LKB-2140 Ultraviolet Photodiode Array detector was used to detect the polymer with a scan range from 190 to 370 nm. 

Both polymers 10 and 11 are soluble in common organic solvents, melt without decomposition, and can be drawn into the fibers. Molecular weights of the polymers 10 and 11, determined by gel permeation chromatography with tetrahydrofuran as the eluant after purification by reprecipitation from benzene-ethanol, showed a broad monomodal molecular weight distribution. The degree of polymerization depends on particle size of sodium metal. Polymers with molecular weights of 23,000-34,000 are always obtained, if fine sodium particles are used. 

The polymerization was carried out in THF under the conditions of high vacuum or argon atmosphere with a catalytic amount of alkyllithium as an initiator. Anionic polymerization of 3a with n-BuLi in THF followed by quenching with ethanol afforded polymer 6 in 56 % yield. The molecular weight distribution of the polymer was determined by gel permeation chromatography (GPC), calibrated by polystyrene standards, with chlorofrom as eluent Mn = 6.1xl0"4, Mw/Mn = 1.3. 

Materials. GMC and PCLS were synthesized by free radical solution polymerization initiated by benzoyl peroxide as described previously (5,6). Nearly mono and polydisperse polystyrenes were obtained from Pressure Chemical Co. and the National Bureau of Standards respectively. Molecular weight and polydispersity were determined by gel permeation chromatography (GPC) using a Water Model 244 GPC, equipped with a set (102-106 A) of —Styragel columns using THF as the elution solvent. The molecular parameters of the above three polymers are listed in Table I. The copolymer, poly(GMA-co-3-CLS), contained 53.5 mole % 3-CLS and 46.5 mole % GMA, as determined by chlorine elemental analysis. The structure of the copolymer is shown in Figure 1. 

Molecular weight and polydispersity were determined by gel permeation chromatography. The values reported are in terms of polystyrene equivalent molecular weights. 

Poly(acrylamide) and its acrylic acid copolymers were obtained from polymerization of the monomers in aqueous solution using ammonium persulfate/sodium bisulfite initiator following the procedure reported by Fong and Kowalski.5 Depending on the amount of initiator used, the average molecular weights of the polymers were between 6,000 to 50,000 as determined by gel permeation chromatography (GPC). Taurine (2-aminoethanesulfonic acid) and sodium formaldehyde bisulfite were purchased from Aldrich and used without purification. 

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