Linear poly , preparative procedures

Trilialophenols can be converted to poly(dihaloph.enylene oxide)s by a reaction that resembles radical-initiated displacement polymerization. In one procedure, either a copper or silver complex of the phenol is heated to produce a branched product (50). In another procedure, a catalytic quantity of an oxidizing agent and the dry sodium salt in dimethyl sulfoxide produces linear poly(2,6-dichloro-l,4-polyphenylene oxide) (51). The polymer can also be prepared by direct oxidation with a copper—amine catalyst, although branching in the ortho positions is indicated by chlorine analyses (52). 

Poly(iV-alllinear poly(isopropylenimine) (PiPI) back in 1974 based on the hydrolysis of poly(2,5-dimethyl-2-oxazoline), prepared by living CROP of the corresponding 2-oxazoline monomer. The PiPI is of interest as it is the simplest PAI with a chiral main-chain structure. Even though this specific example yielded a racemic PiPI, this synthetic procedure also provides access to a PiPI with controlled stereochemistry if... 

The conformational and dynamic properties of cyclic polymers have been the subject of considerable interest over a number of years [73] [74]. The new synthetic procedure developed for the preparation of per-deuterated cyclic and linear poly(dimethylsiloxane) (PDMS) polymers [12] [13] [14] now offers unique possibilities for neutron scattering studies. For the first time, it has allowed sufficient deuterated materials to be available for fractionation using our preparative GPC instrument. The resulting narrow fractions are ideally suited for both static and dynamic studies of cyclic and linear polymers. This range incorporates the critical molar mass for entanglement in PDMS. 

TPEs have also been prepared by grafting from linear maaoinitiators prepared by non-ATRP procedures including polyethylene, polyisobutylene, poly(epichlorohydtine-co-ethylene oxide) elastomer or natural rubber and/or a synthetic diene mbber backbones. 

The procedure described here is not limited to the preparation of polymers such as 2. Starting from the difunctional silane 3 we have synthesized a copolymer, poly(dimethyl-co-isocyanopropylmethyl-siloxane) > as well as a linear homopolymer, poly(isocyanopropyl-methylsiloxane) 8 (Scheme 2). Indeed, preparation of a monofunctional analogue of 2. and h creates the potential for end-capping with an isocyanide function any polymer containing other functional groups, thereby in principle permitting mixed ligand complexes of polymers to be accessed. 

Considerable research effort has been devoted in recent years to the use of chloral derivatives for the synthesis of linear heterocyclic polymers. Of these, the most common are aromatic polyimides [1-12], Many of these polymers have been synthesised from compounds like 4,4 -diaminobenzophenone, and other diamines, which, as demonstrated in the previous chapter, can be obtained from chloral. Polyimides prepared from these diamines were largely synthesised by the conventional two-step procedure [11, 12] involving mild reaction of the diamines with the bis(phthalic)anhydrides, isolation of poly(o-carboxy)amide (PCA) prepolymers, and then processing into products followed by thermal or chemical imidisation [13—16] (Scheme 3.1). Some properties of polyimides prepared from 4,4 -diaminobenzophenone are provided in Table 3.1. 

A procedure similar to that which we have already reported was employed [9,10]. This involves the preparation of a pre-polymer poly(amic acid) (PAA) solution in DMAc, followed by imidization in suspension in paraffin oil. A typical procedure for the preparation of linear functionalized spherical polyimide particulates was as follows. A round-bottomed 3-necked flask was flushed with N2 and charged with a diamine in DMAc. The diamine was completely dissolved in DMAc. While solution was mechanically stirred, finely ground pyromellitic dianhydride (PMDA) was added to the mixture on an ice bath in small portions, and then stirring continued overnight at room temperature. Paraffin oil with poly(maleic anhydride-co-octadec-l-ene)(l l) (O.Swt% in oil) as a suspension stabilizer was added to the flask. The PAA solution was suspended for 2hr at 60T) at the speed of 400rpm. After that, imidization was initiated by dropwise addition of a mixture of acetic anhydride (4.0 molar excess of PMDA used) and pyridine (3.5 molar excess of PMDA used). After 24hr, the polyimide particulates were filtered, washed with dichloromethane and then dried at 80 °C in a vacuum oven. 

Further investigations carried out by Chelushkin et al. [73] for various combinations of micelles formed in aqueous media by ionic amphiphilic diblock copolymers [PS-fc-P4VPQ, poly(styrene)-fetocA -poly(sodium acrylate) (PS- -PANa), and PS- -PMANa)] with oppositely charged linear PEs (polycarboxylates, polysulfonates, polyphosphates, and aromatic, aliphatic, and alicyclic quaternized polyamines) have demonstrated that the solubility of IPECs is decisively determined by (1) the aggregation state of the excess polymeric component (micelles versus individual polymeric coils) and (2) the procedure or method employed for the preparation of such macromolecular co-assemblies. 

Polyphosphinoboranes containing phosphorus and boron linked to each other in polymeric chains have remained elusive for a long time. Recently, catalytic dehydrogenation of the phosphine-borane adducts has been found to be effective to prepare the linear polymer. Thus, thermal treatment of PhPH2.BH3 in the presence of catalytic amounts of [(l,5-COD)Rh( j,-Cl)] affords the linear polymer poly(phenylphosphinoborane), [PhHPBH2]n (see Eq. 1.13) [28-30]. High polymers with of about 33,000 have been isolated by this procedure. 

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