Hydroxy-terminated polystyrene

The simplest case of a polymer molecule which can undergo either cyclization or chain extension is that in which the groups are situated at each end of the polymer chain (which can react together). An example of this type of polymer is a,reacts with a difunctional isocyanate, and our first studies were carried out with this reaction system. Obviously, the chain extension reaction leads to an increased specific viscosity, and cyclization leads to the reverse. 

Reaction of hydroxy-terminated polystyrene with phosgene (38). 

II. B polyethylene glycol, ethylene oxide, polystyrene, diisocyanates (urethanes), polyvinylchloride, chloroprene, THF, diglycolide, dilac-tide, <5-valerolactone, substituted e-caprolactones, 4-vinyl anisole, styrene, methyl methacrylate, and vinyl acetate. In addition to these species, many copolymers have been prepared from oligomers of PCL. In particular, a variety of polyester-urethanes have been synthesized from hydroxy-terminated PCL, some of which have achieved commercial status (9). Graft copolymers with acrylic acid, acrylonitrile, and styrene have been prepared using PCL as the backbone polymer (60). 

The use of these initiators to polymerize LA814 and methylglycolide815 has been reported to proceed in a well-controlled fashion. Block copolymers such as PCL-b-PLA have also been prepared. Elimination of PrOH from the reaction of (270) with preformed hydroxyl terminated polymers, followed by lactone polymerization, yields diblocks of CL with polystyrene or polybutadiene.816 The preparation of an ABA triblock has also been reported (A = CL, B = LA) since propagating chains of PLA do not initiate CL ring opening, (270) was pretreated with hydroxy terminated (PCL-b-PLA)-OH 814... 

HMX HMX HMX HMX HMX HMX HMX HMX HMX HMX HMX HMX HNS NTO NTO/HMX NTO/HMX NTO/HMX PETN PETN PETN PETN PETN PETN PETN PETN PETN PETN RDX RDX RDX RDX RDX RDX RDX RDX RDX RDX RDX RDX RDX TATB/HMX Cariflex (thermoplastic elastomer) Hydroxy-terminated polybutadiene (polyurethane) Hydroxy-terminated polyester Kraton (block copolymer of styrene and ethylene-butylene) Nylon (polyamide) Polyester resin-styrene Polyethylene Polyurethane Poly(vinyl) alcohol Poly(vinyl) butyral resin Teflon (polytetrafluoroethylene) Viton (fluoroelastomer) Teflon (polytetrafluoroethylene) Cariflex (block copolymer of butadiene-styrene) Cariflex (block copolymer of butadiene-styrene) Estane (polyester polyurethane copolymer) Hytemp (thermoplastic elastomer) Butyl rubber with acetyl tributylcitrate Epoxy resin-diethylenetriamine Kraton (block copolymer of styrene and ethylene-butylene) Latex with bis-(2-ethylhexyl adipate) Nylon (polyamide) Polyester and styrene copolymer Poly(ethyl acrylate) with dibutyl phthalate Silicone rubber Viton (fluoroelastomer) Teflon (polytetrafluoroethylene) Epoxy ether Exon (polychlorotrifluoroethylene/vinylidine chloride) Hydroxy-terminated polybutadiene (polyurethane) Kel-F (polychlorotrifluoroethylene) Nylon (polyamide) Nylon and aluminium Nitro-fluoroalkyl epoxides Polyacrylate and paraffin Polyamide resin Polyisobutylene/Teflon (polytetrafluoroethylene) Polyester Polystyrene Teflon (polytetrafluoroethylene) Kraton (block copolymer of styrene and ethylene-butylene)... 

Chlorinated paraffins, which contain up to 60-70% chlorine, are low in cost and are used as secondary plasticizer in PVC wire and cable insulations. Perchlorobicyclopentadiene has little plasticizing action and is used in polyethylene. Some of the more expensive bromine-containing fire retardants which have been used in the ratio of 5 p.p.h. in polystyrene foam, may be reduced to 0.5 p.p.h. by adding synergists such as peroxides or nitroso compounds. The reaction-type retardants, such as chlorendic acid and anhydride, hydroxy-terminated phosphonated esters, and specific brominated aliphatic esters, are admixed to rigid and flexible polyurethane foams, reinforced polyesters, phenolics, and epoxy resins. 

A more recent report discussed a microwave-assisted tetronate synthesis entailing domino addition/Wittig olefinations of polymer-bound a-hydroxy esters with the cumulated phosphorus ylide Ph3P=C=C=0 [59]. The desired immobilized a-hydroxy esters can be obtained by microwave-mediated ring opening of the corresponding glycidyl esters by OH-, NH-, or SH-terminal polystyrenes of the Merri-... 

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... 

Isophthaloyl chloride has also been employed in block copolymer preparation. Poly(m-phenylene isophthalamide) and either poly-(ethylene oxide) or poly(dimethyl siloxane) block copol3miers have been prepared by terminating the former with isophthaloyl chloride and subsequently adding hydroxy terminated poly(ethylene oxide) or poly(dimethyl siloxane)(79). Block copolymers were also produced when a polyformal was capped with 1,6-hexandiol, and then heated in the presence of poly(tetramethylene terephthalate)(80). In another interesting application, polyesterpolyether block copolymers of poly-(ethylene terephthalate) and a number of polyglycols have been reported(Sl). Their synthesis involves esterification, catalyzed by zinc acetate/titanyl oxalate. ABA block polymer of 2-hydroxyethyl methacrylate and styrene was prepared by coupling -NH2 terminated PHEMA and isocyanate terminated polystyrene. The latter material was prepared by UV polymerization of styrene in the presence of bis(p-isocyanatophenyl)disulfide (82),... 

Recently, impact modifiers have been developed for plastics other than PVC. Polybutylene and other olefinic thermoplastic elastomers, for example, are being used to enhance the processability, toughness, and heat stability of polypropylene film. Hydroxy-terminated polyethers are being used to increase the impact resistance of polystyrene. Other conunon applications are polycarbonate, polyurethane, thermoplastic polyester, epoxy, and polysulfone. 

Ethylene polymerized with diethyl peroxydicarbonate contains terminal ester groups (41). Using C-labeled cyclohexane peroxydicarbonate, the fate of the primary radicals during the polymerization of methyl methacrylate (MMA) and styrene has been studied (42). Although this reference includes no detailed analysis of the products, it indicates that ROOCO-terminated polystyrene telechelics may be obtained by this technique. A similar method has been used for the preparation of telechelic polybutadiene (43). The carbonate end groups are easily modified into terminal hydroxyl groups by hydrolysis. Hydrogenation of the carbonate functionahzed telechelic polybutadiene, followed by hydrolysis, srields hydroxy-terminated polyethylene telechelics. 

Polymerization of styrene with these initiators gave hydroxy and protected amino-terminated polymers with narrow polydispersities (i.e., MJM 1.1-1.6). The r-Boc amino group in the latter case can be deprotected by trifluoroacetic acid to eventually yield monofunctional amino-terminated polystyrene. An alternative procedure is based on the use of a functional initiator possessing the desired groups (Scheme 26) together with TEMPO. 

C ) with a 4-hydroxy-2,2,6,6-tetramethylpiperidine-N-oxyl (TEMPOL) terminated polystyrene (PS) (M = 12000gmor M /M = 1.16) at 95°C in toluene [19]. In a similar reaction, but with 2,2,6,6-tetramethylpiperidine-N-oxyl (TEMPO) as the stable counter radical, a di-adduct was formed in high yield even when a four-fold excess of Qo per PS-TEMPO was used [20]. The two chains are attached in the 1,4 positions on the same six-membered ring, only one double bond is opened and no TEMPO is present on the fullerene (Scheme 5.2). 

The synthesis of block copolymers can be easily carried out if functional groups such as acid chloride ( COCl), amines ( -NH2), or alcohols (-"UH) are present at chain ends. This way, a polymer of one kind (say, polystyrene or polybutadiene) with dicarboxylic acid chloride (ClCO COCl) terminal groups can react with a hydroxy-terminated polymer (OH> OH) of the other kind (say, polybutadiene or polystyrene), resulting in an AB type block copolymer, as follows ... 

Block copolymers were synthesized by a combination of fipase-catalyzed polymerization and atom transfer radical polymerization (ATRE). " " At first, the polymerization of 10-hydroxydecanoic acid was carried out by using lipase CA as catalyst. The terminal hydroxy group was modified by the reaction with a-bromopropionyl bromide, followed by ATRP of styrene using CuCE2,2 -bipyridine as catalyst system to give the polyester-polystyrene block copolymer. Trichloromethyl-terminated poly(e-CL), which was synthesized by lipase CA-catalyzed polymerization with 2,2,2-trichloroethanol initiator, was used as initiator for ATRP of styrene. 

---