Methods for recovering monomers from polymers, such as polyurethanes (including thermoset polyurethanes) include heating the polymer to depolymerize the polymer and release the monomer. The monomer may be directly recovered. The polymer may include a poly(β-methyl-δ-valerolactone) (PMVL) block and the monomer recovered may be β-methyl-δ-valerolactone (MVL).

Methods for recovering monomers from polymers, such as polyurethanes (including thermoset polyurethanes) include heating the polymer to depolymerize the polymer and release the monomer. The monomer may be directly recovered. The polymer may include a poly(-methyl--valerolactone) (PMVL) block and the monomer recovered may be -methyl--valerolactone (MVL).

Block copolymers include a poly -methyl--valerolactone (PMVL) block. The PMVL blocks can be formed from biosynthesized -methyl--valerolactone (MVL). The PMVL block may be formed from biosynthesized -methyl--valerolactone (MVL) with a .sup.14C/.sup.12C ratio greater than zero. The block copolymers can include hard blocks. The block copolymers can be thermoplastic elastomers. The block copolymers may include a polylactic acid (PLA) block.

Methods for recovering monomers from polymers, such as polyurethanes (including thermoset polyurethanes) include heating the polymer to depolymerize the polymer and release the monomer. The monomer may be directly recovered. The polymer may include a poly(-methyl--valerolactone) (PMVL) block and the monomer recovered may be -methyl--valerolactone (MVL).

Methods for recovering monomers from polymers, such as polyurethanes (including thermoset polyurethanes) include heating the polymer to depolymerize the polymer and release the monomer. The monomer may be directly recovered. The polymer may include a poly(-methyl--valerolactone) (PMVL) block and the monomer recovered may be -methyl--valerolactone (MVL).

A polybutadiene having a hydroxyl group at a terminal end thereof is reacted with a lactone compound such as an -caprolactone to obtain a polymer polyol represented by formula (I): HOX.sup.1YX.sup.2OH (wherein X.sup.1 and X.sup.2 each independently represents a polyester component and Y represents a polybutadiene component), the polymer polyol is reacted with an unsymmetric diisocyanate to obtain a urethane prepolymer, and then the urethane prepolymer is reacted with a chain extender to obtain a polyurethane.

A polybutadiene having a hydroxyl group at a terminal end thereof is reacted with a lactone compound such as an -caprolactone to obtain a polymer polyol represented by formula (I): HOX.sup.1YX.sup.2OH (wherein X.sup.1 and X.sup.2 each independently represents a polyester component and Y represents a polybutadiene component), the polymer polyol is reacted with an unsymmetric diisocyanate to obtain a urethane prepolymer, and then the urethane prepolymer is reacted with a chain extender to obtain a polyurethane.

The invention relates to a two-component or multi-component system comprising: at least one polyol component 1 that has i) at least one polyol, ii) at least one inorganic thickener (a1), and iii) at least one wetting and dispersing agent (a2) which inhibits the thickening effect of said inorganic thickener (a1); as well as at least one polyisocyanate component 2 that comprises i) at least one polyisocyanate; where (A) either the polyisocyanate component 2 comprises at least one component (b1) that at least partially cancels the inhibition of the thickening effect of the inorganic thickener (a1); and/or (B) at least one isocyanate-free component 3 comprises at least one component (b1) that at least partially cancels the inhibition of the thickening effect of the inorganic thickener (a1); said wetting and dispersing agent (a2) being non-reactive to the at least one polyol, and the polyisocyanate component 2 being reactive to the polyol component 1. The invention also relates to a substrate coated with a system according to the invention, and to the use of at least one inorganic thickener (a1) and at least one wetting and dispersing agent (a2) which inhibits the thickening effect of said inorganic thickener (a1), in order to provide a latent thickening effect for a composition that contains at least one polyol.

Block copolymers include a poly -methyl--valerolactone (PMVL) block. The PMVL blocks can be formed from biosynthesized -methyl--valero lactone (MVL). The block copolymers can include hard blocks. The block copolymers can be thermoplastic elastomers.