Urethans amides

One of the most important uses of end-functionalized polymers is the preparation of block copolymers.73,74 The reactions are identical to the chain extensions already mentioned, except that the sequences being joined are chemically different. In the case of the -OSilCR Y chain ends mentioned above, R is typically (CH2)3 5 and Y can be NH2, OH, COOH, CH=CH2, and so on The siloxane sequences containing these ends have been joined to other polymeric sequences such as carbonates, ureas, urethanes, amides, and imides. 

J.H. Fabris, Novel poly(urethane-amide)s from polyurethane prepolymer and reactive polyamide. Preparation and Properties. Adv. Urethane Sci. Technol., 4, 89-111 (1976). 

The rate of reversion, or hydrolytic instability, depends on the chemical structure of the base polymer, its degree of crosslinking, and the permeability of the adhesive or sealant. Certain chemical linkages such as ester, urethane, amide, and urea can be hydrolyzed. The rate of attack is fastest for ester-based linkages. Ester linkages are present in certain types of polyurethanes and anhydride cured epoxies. Generally, amine cured epoxies offer better hydrolytic stability than anhydride cured types. 

The modification linkages include urethane, amide, imide, carbodiimide and oxazolidone linkages. A urethane-modified isocyanurate foam (trade name Airlite Foam SNB, Nisshinbo, Ind. Inc.) was first applied to the petrochemical industry as a seamless fire-resistant insulant in 1965 (39). 

Of com e, PVC is only one example of a plastic but other plastics based on PU will also be susceptible. The ingredients in PU that are susceptible m include esters, ureas, urethanes, amides, biurets and allophanates. 

Passive hydrolysis. Esters, carbonates, amides and urethanes are susceptible to hydrolysis. Drugs linked with the spacer via such bonds will be released in aqueous media. The rate of release will decrease in the order ester > carbonate > urethane > amide. Cleavage may also occur at the level of the spacer-backbone bond so that spacer-drug moieties can be released as well. 

Synthesis of Poly(ether urethane amide) Segmented Elastomers... 

PENHASIET AL. Pofy(Mur urethane amide) S naited Elastomas... 

Jonqui res A, Clement R, Lochon P. New film-forming poly(urethane-amide-imide) block copolymers influence of soft block on membrane properties for the purification of a fuel octane enhancer by pervaporation. Eur Polym J 2005 41(4) 783-95. 

Diol linseed fatty amide is treated with TDI at room temperature in a one shot technique to obtain polyurethane, using a minimal amount of xylene as the solvent and without any chain extender or catalyst. The reaction is stopped when it has reached the desired hydroxyl value and the solvent is removed through a rotary vacuum evaporator to obtain poly(urethane amide) resin. 

Mesua ferrea L. seed oil-based polyurethane (PU) resins, poly(urethane ester) (PUE) and poly(urethane amide) (PUA) with varying NCO/OH ratios have been prepared using the one shot process in the presence of DBTDL as a catalyst. Monoglyceride of the oil is used for poly(urethane... 

Mesua ferrea L. seed oil-based poly(urethane ester) and poly(urethane amide) resins with an NCO/OH ratio of 0.5 are modified by commercially available bisphenol-A based epoxy resin and partially butylated ME resin... 

Two types of environmentally friendly jute fibre reinforced green composites have been studied. These are based on Mesua ferrea L. seed oil-based poly(urethane ester) and poly(urethane amide) resin blends with commercially available partially butylated melamine-formaldehyde and epoxy resins by solution impregnation and hot-curing methods. The composites were cured at a temperature of about 130-140°C under a pressure of 35.5 kg cm for around 2 h.The physical, mechanical and chemical properties of the epoxy-modified polyurethane composites were better than those of the MF-modified composites. They also possessed excellent chemical resistance and hydrolytic stability in water, acid and salt solutions, making them useful for low load-bearing applications. 

Conductive polymer nanocomposites may also be used in different electrical applications such as the electrodes of batteries or display devices. Linseed oil-based poly(urethane amide)/nanostuctured poly(l-naphthylamine) nanocomposites can be used as antistatic and anticorrosive protective coating materials. Castor oil modified polyurethane/ nanohydroxyapatite nanocomposites have the potential for use in biomedical implants and tissue engineering. Mesua ferrea and sunflower seed oil-based HBPU/silver nanocomposites have been found suitable for use as antibacterial catheters, although more thorough work remains to be done in this field. ° Sunflower oil modified HBPU/silver nanocomposites also have considerable potential as heterogeneous catalysts for the reduction of nitro-compounds to amino compounds. Castor oil-based polyurethane/ epoxy/clay nanocomposites can be used as lubricants to reduce friction and wear. HBPU of castor oil and MWCNT nanocomposites possesses good shape memory properties and therefore could be used in smart materials. ... 

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