Hydroxy-terminated polymer

Many examples exist where a polymerization has been continued by ATRP. V" Often the procedure involves functionalization of a hydroxy-terminated polymer with bromoisobutyroyl (BriBBr, 314) or bromoisopropionoyl (BriPBr, 315) bromide. Examples include polyethylene oxide)044,646 and polypropylene... 

M.B. Frankel et al, Smokeless Composite Propellants Containing Carboxy- or Hydroxy-Terminated Polymers and a Nitroorganic Oxidizer , USP 3853646 (1974) CA 83, 12972 (1975) 37) A. Reichel et al, High Explo-... 

The effects of the feed ratio in the lipase CA-catalyzed polymerization of adipic acid and 1,6-hexanediol were examined by using NMR and MALDI-TOF mass spectroscopies. NMR analysis showed that the hydroxyl terminated product was preferentially formed at the early stage of the polymerization in the stoichiometric substrates. As the reaction proceeded, the carboxyl-terminated product was mainly formed. Even in the use of an excess of the dicarboxylic acid monomer, the hydroxy-terminated polymer was predominantly formed at the early reaction stage, which is a specific polymerization behavior due to the unique enzyme catalysis. 

Functionalization of these reactive anionic chain ends can be achieved by a variety of methods all based on the general concepts of carbanion chemistry. For example, reaction with C02 or succinnic anhydride leads to the carboxy terminated derivatives [10], while hydroxy-terminated polymers can be easily obtained by reaction with ethylene oxide (Scheme 3) [11]. In select functionalization reactions, such as alkylation with p-vinyl benzyl chloride, the nucleophilicity of the carbanionic species may be necessary and this can be achieved by reaction of the chain end with 1,1-diphenylethene followed by functionalization [12,13]. 

The most important tetrahydrofuran polymers are the hydroxy-terminated polymers, that is, the 0C,C0-poly(tetramethylene ether) glycols used commercially to manufacture polyurethanes and polyesters (see Urethane polymers Polyesters, thermoplastic). 

Under the conditions used for the syntheses of these compounds, as well as the expected hydroxy-terminated polymers, which predominate due to the excess of the diol reactant, polymers terminated with acid or acid amide groups are also formed from the nitrile groups of AIBN. 

The objectives of this study were to extend these synthetic methods to the preparation of low molecular weight, hydroxy-terminated polymers containing acetylenic bonds and evaluating these prepolymers in castable solid propellant formulations. Since 2-butyne-l,4-diol was commercially available, the formation of polyacetals from this glycol seemed to be an attractive route to the desired polymers. It was believed that the rigid triple bond would inhibit the cyclic acetal formation observed by the earlier workers with the lower members of the saturated glycol series. Thus, in an acetal interchange reaction a linear polymer (I) should be favored over the cyclic acetal (II) ... 

Thus, termination of oxazoline polymerization with potassium hydroxide gave hydroxy-terminated polymers, which in the presence of tin octoate were capable of initiating the anionic polymerization of -caprolac-tone [287] giving the corresponding block copolymer, acting as effective compatibiliser. 

Rose [50] carried out one of the earliest, really thorough investigations of the kinetics of polymerization of a cyclic ether polymerization. He studied oxetane polymerizations initiated by BF3. Rose was aware from the work of Farthing and Reynolds [51] that polymerization does not occur when BF3 comes into contact with pure, dry monomer. However, simultaneous addition of water, ethanol or hydroxy terminated polymer is sufficient to initiate polymerization. Since Rose [50] observed polymerization in his sytem, he assumed that it was not completely dry and discussed his results assuming water is a co-catalyst. As the concentration of water increased, the rate of polymerization at first increased. The rate... 

Maleic anhydride (72) when mixed with triphenylbismuthine in a ratio ranging from 1 1 to 1 1.5 provided a curing catalyst for a propellant composite comprising an oxidizer, isocyanate curing agent, and a hydroxy-terminated polymer binder. The resulting composite showed improved modulus and/or stress values for use with propellants <91 Ml 208-06). 

Hydroxy-terminated liquid polybutadienes are prepared for reactions with diisocyanates to form elastomeric polyurethanes (see Chapter 6). Such materials can be prepared by anionic polymerizations as living polymers and then quenched at the appropriate molecular weight. These polybutadienes can also be formed by a free-radical mechanism. The microstructures of the two products differ, however, and this may affect the properties of the finished products. To form hydroxy terminated polymers by a free-radical mechanism, the polymerization reactions may be initiated by hydroxy radicals from hydrogen peroxide. 

Polycaprolactone (Mn = 4000 and 37,000). Methoxy and hydroxy terminated polymer chains CO2 evolution, weight loss, and molecular weight Compost inoculum Actinomycetes species isolated from compost [111]... 

Macromonomers can be synthesized from a hydroxy-terminated polymer by reaction with methacryloyl chloride (255). 

Hydroxy-terminated polymers prepared in this manner were used to build more complex macromolecular architectures such as graft copolymers [50] or block copolymers [51]. Using a 1,3-dithiepine instead of a 1,3-dioxepine as sacrificial monomer, allylic thiol polymer end groups could be obtained [52]. The poly(l,3-dithiepine) block was cleaved (sacrificed) under hydrogenation conditions using Raney-Nickel. 

The hydroxy-terminated polymers have poor thermal stability. Loss of a proton, possibly to an initiator tesidue, from a chain end gives an anion capable of decomposing to formaldehyde by the reverse of the propagation process. The stability of the polymer is therefore improved if the hydroxy end-groups are removed by esterification ... 

This limitation is overcome when the elastomer is cast from a mixture consisting of a linear polyester or poly ether, diisocyanate and glycol or diamine. In this process, the hydroxy-terminated polymer (e.g., poly(ethylene adipate) or poly(oxytetramethylene) glycol) is treated with an excess of diisocyanate (e.g., naphthylene 1,5-diisocyanate, tolylene diisocyanate or diphenylmethane 4,4 -diisocyanate). The product is a pre-polymer which is, in effect, a mixture of isocyanate-terminated polymer and unreacted diisocyanate. The pre-polymer is then mixed with either a glycol (e.g., 1,4-butanediol or 1,6-hexanediol) or diamine (which is usually a deactivated amine such as 3,3 -dichloro4,4 -diamino-diphenylmethane (MOCA)). The mixture is poured into a heated mould where it quickly sets. After about 30 mins the casting is removed from the mould and cured at about 110°C for 24 hours. 

In these systems, isocyanates and hydroxy-terminated polymers are mixed immediately prior to use. After the components are mixed curing takes place by... 

The use of hydroxy-terminated polysulphide polymers is limited to applications where outstanding solvent resistance is required. The reason for this is that the best solvent resistance is shown by polymers with a high sulphur content but these cannot be prepared with thiol end-groups by the hydrosulphide/sulphite treatment because sulphite removes high rank sulphur from the polymer backbone. (See Section 17.2.4.2.) Thus since poly sulphide polymers of high sulphur content cannot be subjected to this after-treatment, they are supplied as hydroxy-terminated polymers of high molecular weight. 

Because of their high molecular weight, the hydroxy-terminated polymers are difficult to process and a chemical plasticizer is usually added to facilitate milling. The plasticizer is a disulphide such as benzothiazyl disulphide (mercaptobenzothiazole disulphide, MBTS) interchanges of the following type... 

In order to obtain the equivalent weight of the hydroxy terminated polymer, EWpon the molecular weight of the silyl group and that of the substituted proton must... 

Carboxylic functional polyols can be prepared by reacting hydroxyl terminated polyethers with unsaturated acids and a free radical initiator. Also carboxylic groups can be added to poly(ester/ethers) or other hydroxy terminated polymers by reacting with dianhydrides. 

Block copolymers could also be prepared by the bulk reaction of mixtures of amino-terminated aliphatic polyamides and polyethers using monosubstituted bisoxazolinones.In the same paper, it was reported that the coupling also succeeded for mixtures of hydroxy-terminated polymers and amino-terminated polymers, making this synthetic method applicable to a large range of polymers. 

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