Solution copolymerizations initial experiments

Unfortunately there seems to be no supplementary evidence on copolymerization initiated by phosphines. In a typical experiment, a solution of acrylonitrile in petroleum ether is treated with a little triethyl phosphine. A greenish-brown product settles on the walls of the flask. It is soluble in acetone, furfural, methyl ethyl ketone and DMF. Polymer precipitated from acetone by toluene is of low molecular weight and contains perhaps 0.5% combined phosphorus. In similar experiments it is possible to obtain pale yellow polymers with number average molecular weights of around 30,000 and with about one atom of P per polymer chain. On the basis of these results Horner and coworkers proposed the scheme (72) ... 

Solution Copolymerizations. Our primary objective in this preliminary study was to gain a qualitative understanding of the copolymerization behavior of VEC with various types of unsaturated monomers. Particularly, we wanted to determine if VEC could be incorporated into a variety of polymer types of interest to the coatings industry. Since VEC is used to provide cyclic carbonate functionality for subsequent reaction or crosslinking, limited amounts of VEC are used in the copolymerizations. A semi-batch process was used in the copolymerization experiments to approach starved-feed conditions. Starved-feed conditions can result in copolymers with more uniform composition since the conversion is kept high in the reactor. While there are a large number of variables to consider, we elected to focus on monomer composition, polymerization temperature, and initiator level. 

Table III lists the initial solution copolymerization experiments conducted using vinyl ester monomers. Since our main objective is the synthesis of polymers for durable coatings, these experiments were conducted using more hindered vinyl monomers which are reported to have better durability than vinyl acetate.

No triester of levoglucosan was found92 that polymerized at temperatures much below 0°. At —78°, the triacetate complexed with phosphorus pentafluoride, and, at high concentration, precipitated from solution.91 The tris(monofluoroacetate) failed to polymerize under a variety of conditions.91 The trinitrate polymerized at 0°, but the product was not fully characterized.92 Polymerization of the triacetate proceeded to reasonable conversions with a number of catalysts at 0°, but the viscosity and the stereoregularity of these polymers were low.92 In a simple, copolymerization experiment, it was demonstrated that the low polymerizability of levoglucosan triacetate was due not only to a failure to initiate but also to sluggish propagation.92... 

An immobilized Ru-PyBOx catalyst 56 was synthesized by thermally induced radical copolymerization and used to catalyze the flow cyclopropanation reaction between styrene and ethyldiazoacetate (Scheme 4.79), building on initial work performed in batch [179]. For the flow example, a range of experiments using the starting materials in CH2C12 solution, neat or in scC02 were assessed and the results are summarized in Table 4.2 [180],... 

The copolymerizations were carried out under argon using a 1 L Biichi A6 Type I autoclave equipped with an additional external cooling system. For the standard experiments, the reactor was evacuated at 95 C for 1 h and subsequently charged with a solution of norbornene in toluene, 190 mL toluene solvent, 500 mg MAO in 10 mL toluene (from Witco/Crompton), and ethylene at different pressures. Norbornene was dried over triisobutylaluminum and subsequently distilled before use. Polymerizations were initiated by injection of a toluenic metallocene solution into the reaction vessel... 

In order to produce an asymmetric inductive reaction on the interface of chiral materials, we have conducted the same type of experiments with an optically active surface active agent. Using soybean lecithin ([a] d 7.8°) (XXXVI), styrene was emulsified into the aqueous solution of maleic acid and potassium persulfate was added as radical initiator the copolymerization was carried out at 40°C [22]. 

All attempts to copolymerize 1 with other vinyl monomers were unsuccessful until Salamone and coworkers obtained a 1,2-addition copolymer 4 of 1 (R = H] and 4-vinylbenzenesulfonate, 20, obtained by spontaneous polymerization oi the two monomers as a melt or in concentrated aqueous solution [61]. Vinyl-type copolymers of 1 and 20, and 1 and 21 were also obtained by initiation with radicals (e.g. from ACVA), light or y-radiation. These experiments are summarized in Table 6.3.1. Copolymerization of 1 (R = H) with AMPS 21 is complicated when carried out as a spontaneous (i.e. absence of an initiator) process in water, methanol, or iV,iV-dimethylformamide (DMF). Two homopolymers derived from 1 (R = H), the 1,2-addition polymer, 2 (R = H), and the polyionene, 7. are obtained along with poly AMPS. Similar attempts to form copolymer from 1 (R = H) and vinylsulfonate have been unsuccessful. In fact, the latter monomei resisted all conditions of polymerization and 1 (R = H) formed the ionene 7 from a melt or in dilute aqueous solution (< 1.0 m) and yielded 2(R = H) in concentrated aqueous solution. Table 6.3.1. Recall that this behavior duplicates that reported for 1 (R = H) by Ringsdorf and others. Ringsdorf attributed the change in structure of homopolymer to micellization of 1 (R = H) in concentrated aqueous solution. 

---