Styrene-terminated polypropylene

Doi et al. 84) have synthesized a new type of diblock copolymer of propylene and styrene by the coupling reaction between the iodine-terminated polypropylene (4) and monofunctional living polystyrene anion (11) in toluene at 50 °C, as represented by Eq. (47). 

The metaUation reaction of p-MS-terminated polypropylene (PP-t-p-MS) (I in Scheme 11) was carried out under heterogeneous reaction conditions by suspending the powder form of PP in s-BuLi/TMEDA/cyclohexane solution. To examine the efficiency of the reaction, some of the metallated polymer (II) was terminated with Cl-Si(CH3)3 and examined by H NMR measurement, showing about 85% conversion. Most of the Hthiated PP-t-p-MS (II) was used to prepare diblock copolymers. By mixing polymer powder with styrene monomer in cyclohexane solvent, the living anionic polymerization took place to produce PP-6-PS diblock copolymer (III). After the reaction, the product was vigorously extracted by refluxing THF to... 

In a recent development, a new process of preparing borane-terminated isotactic polypropylene (z -PPs) via an in situ chain-transfer reaction was achieved by a styrene/hydrogen consecutive chain-transfer reagent, which avoids the use of a B—H containing chain-transfer agent.74 This has resulted in the utilization of milder polymerization conditions due to the use of the alkylaluminoxane cocatalyst (MAO) (50) (Fig. 33), which cannot normally be used in the presence of a B—H chain-transferring... 

The concept of PO macroinitiators centers on the introduction of an initiation moiety into an olefinic polymer chain for polymerization. The most effective route for preparing PO macroinitiators is by employing functional polyolefins containing hydroxyl groups or other reactive groups. These functional POs are prepared by copolymerization of olefins with functional monomers and post-polymerization reaction, as mentioned above. In the case where an initiation moiety was at the chain-end of the polyolefins, a block type copolymer is produced. It has been reported that thiol-terminated PP was used as polymeric chain transfer agent in styrene and styrene/acrylonitrile polymerization to form polypropylene-b/odc-polystyrene (PP-b-PS) and polypropylene-btock-poly(styrene-co-acrylonitrile) (PP-b-SAN) block copolymer [19]. On the other hand, polymer hybrids with block and graft structures can be produced if initiation moieties are in the polymer chain. 

Polymethylmethacrylate Polystyrene Polyvinyl alcohol Polypropylene Polyacrylonitrile Polyvinyl chloride Nitrocellulose Polyethylene Polytetrafluorethylene Poly a methyl styrene Hydroxy-terminated polybutadiene filled with ammonium perchlorate Hydroxy-terminated polybutadiene filled with potassium chloride Nylon 66... 

One can also make combined acrylic/urethane (hybrid) aqueous dispersions (33). Acrylic monomers are emulsion polymerized in the presence of an aqueous dispersion of a hydroxy-terminated polyurethane. The polyurethane stabilizes the aqueous dispersion, minimizing need for surfactant. Coalescence requires balance of the Tg of both the urethane and acrylic parts of the system. Compositions based on an IPDl/polypropylene glycol/DMPA urethane with styrene/methyl methacry-late/butyl acrylate are reported to form films at low temperatures. 

When an equimolar mixture of styrene and MA, at 50-70°C, is injected into polyethylene, polypropylene, polystyrene, and others, at a temperature of 120°C, preferably at 150-200°C, polymerization is initiated and the growing chains terminate by insertion into the polymer.It is claimed that activated complexes initiate the polymerization, but this is doubtful, since the styrene-MA complex fails to exist at the 120-150°C polymerization temperature (see Sec. 10.2.15). In most cases, due to temperature and dilution effects, the pendent alternating units are very short, i.e., 2-10 alternating units. Low-density polyethylene because of the tertiary carbon atoms at branch points grafts much easier than high-density polyethylene, under comparable conditions. 

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