A sample of copolymer of styrene and l,4-divinyl-2,3,5,6-tetrachlorobenzene was prepared and fractionated. Using the fractionated copolymers, effects of chain branching on the intrinsic viscosity and sedimentation coefficient were studied experimentally. It was found that in both theta and good solvents, the intrinsic viscosity of the branched polymers obeyed a new semiempirical relationship, [1/]b=g0 · 6 [17]i. Here [1/h is the intrinsic viscosity of a linear polymer having the same molecular weight as the branched one and g is the contraction factor which is defined as the ratio of the mean-square radii of gyration between the branched and linear polymers, i.e., g=(S 2 )b/(S 2 )1. It was also found that the sedimentation coefficient in theta solvent agreed with the theoretical value obtained by Kurata and Fukatsu. The degree of branching estimated from the intrinsic viscosity or sedimentation coefficient was in close agreement with the value estimated from consideration of the copolymerization kinetics.KEY WORDS Branched Polymer / Polystyrene / Degree of Chain Branching / Intrinsic Viscosity / Sedimentation Coefficient / MeanSquare Radius of Gyration / Theta Solvent / Zimm-Stockmayer Theory / Kurata-Fukatsu Theory / In this series of papers, we report the results of a systematic study which has been performed to develop a quick and simple method of estimating the degree of long-chain branching in a polymer molecule.According to Zimm and Stockmayer, 1 the effect of chain branching on the molecular dimension in solution is expressed aswhere

Human amniotic epithelial (hAE) and mesenchymal (hAM) cells are believed to have the potential to differentiate into various functional cells, such as neurons, hepatocytes, cardiomyocytes, and pancreatic beta cells. However, cell transplantation has been performed by injection of cell suspensions, and thus it is difficult to control shape, size, location, and functions of differentiated cells. To overcome these problems, we developed a novel temperature-responsive culture surface coated with elastic protein-based polymer. By reducing the temperature using a polyvinylidene difluoride (PVDF) membrane, the primary hAE and hAM cell sheet can detach from the coated surface. The recovered cell sheet can be transferred and can re-adhere and re-proliferate on another surface. This represents the first report of harvesting of primary hAE and hAM cell sheets using the novel temperature- responsive polymer. These findings suggest that this new technique of cell sheet detachment from noncytotoxic, highly biocompatible protein-based polymer-coated surfaces may be useful in tissue engineering, as well as in the investigation of hAE and hAM cell sheets for transplantation.

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An iterative computer method was proposed for estimating the degree of branching and molecular weight distribution simultaneously from a pair of measurements on intrinsic viscosity and gel-permeation chromatography. The validity of the method as applied to randomly branched polymers was tested by using both fractionated and unfractionated samples of branched polystyrenes. It was experimentally concluded that the average number of branch points per unit molecular weight, A, can be determined by this method with accuracy of about 15%, and the weight-average molecular weight with accuracy of about 10%.