120 u00b0 c preferably 0 u00b0 c to 100 u00b0 c or from ambient temperatures e g 15 u00b0 or 20 u00b0 c to 50 u00b0 60 u00b0 70 u00b0 or 80 u00b0 c the amount of chain terminator solvent compounds may vary depending on the polymer molecular weight from abut 1 part of the chain transfer agent up to about 300 parts of the chain transfer agent during the polymerization a chain transfer reaction takes place which involves the extraction of the hydrogen atom linked to the tertiary carbon atom a process which initiates a new polymer chain the global transfer constant c tr is defined as the ratio between the constants relative to the transfer reaction k tr 39 and the polymerization constant k p 39 this is expressed as c tr k tr 39 k p 39 which equals approximately 1 u00d7 10 4 preferred ratios of monomer to chain transfer agent range from bout 1 20 to about 1 200 with more preferred ratios ranging from about 1 25 to about 1 150 illustrative preferred ratios are 1 50 and 1 100 the polymerization products are isolated by known techniques for example the solvent may be partially or totally removed by distillation preferably under vacuum the crude material can be conveniently isolated by dilution with an appropriate solvent for example diethyl ether where desirable and or necessary for further utilization of the oligomerized products for effecting the graft conjugation with drugs and enzymes the polymer product is processed to produce one with a low level of polydispersion i e high level of narrow molecular weight distribution and one end mono functionality among the techniques for achieving this are gel permeation chromatography.