ABSTRACT:The action of two complementary chain extenders is studied in model systems as well as in poly (ethylene terephthalate) (PET ) and nylon-6. Chain extenders are low molecular weight compounds that can be used to increase the molecular weight of polymers in a short time. The reaction must preferably be fast enough to execute this step in an extruder. 1,3-Phenylene bis(2-oxazoline-2) (PBO ) and isophthaloyl biscaprolactamate (IBC ) are used in this study. Bisoxazolines react quickly with carboxylic acids. With model compounds it is shown that, under processing conditions, high conversions can be reached. However, the conversion is not complete. The high rate and the absence of volatile reactants are the most important characteristics of this reaction. Bislactamates are suitable coupling agents for hydroxy and amino functional polymers. The path of this coupling reaction depends on the type of nucleophile and on the reaction temperature. Under mild conditions the elimination of caprolactam is the main reaction. Under more severe conditions the ring opening mechanism may also be operative. The increase of the viscosity is studied with one as well as with a mixture of the two chain extenders. The effect is larger when both types of chain extenders are used simultaneously.

SummaryIf living poly(vinyl ethers) are terminated with a large excess of methanol, containing aqueous ammonia, well-defined products are obtained. If only a slight excess of methanol is used, aldehydes and coupling products are formed. Sowever, termination with an excess of a hydroxy terminated polymer is cumbersome. According to a given reaction scheme, the termination with methanol in the presence of an anhydrous organic base, should give better results. With two equivalents of triethylamine with respect to the initiator only two equivalents of methanol are needed to give a clean reaction. With this recipe block copolymers of poly(vinyl ether) and poly(ethylene glycol) are prepared.

Combination of hexa(chloromethyl)melamine (HCMM) and zinc chloride was found to be a multifunctional initiator system for the living cationic polymerization of isobutyl vinyl ether. HCMM was synthesized by reaction of hexa(methoxymethyl)melamine and boron trichloride. Characterization of the polymers by means of GPC and 1H NMR showed that initiation was rapid and quantitative and that the initiator is hexafunctional, leading to six‐armed star‐shaped polymers.

No abstract