Acetal metathesis polymerization
View Patent ↗A method of preparing a polyacetal comprising polymerization of a mixture comprising a plurality of at least one bis-acetal monomer in the presence of an acid catalyst that promotes the metathesis of the acetal units. The bis-acetal can be formed from an acid catalyzed exchange between a mono-acetal monomer with a diol. The formation of the bis-acetal and the polyacetal can be carried out simultaneously. The diol can be isolated from a biorenewable source and the ultimate polyacetal is a degradable or biodegradable polymer.
1. A method of preparing a polyacetal comprising the steps of:
providing a polymerization mixture comprising a plurality of bis-acetal monomers of the structure:
wherein R′ is independently C 1 to C 5 alkyl, R is one or more substituted or unsubstituted: C 5 to C 24 alkylene; C 4 to C 24 alkenylene; C 6 to C 14 arylene; C 7 to C 24 alkylarylene; heteroatom or carbonyl interrupted C 3 to C 24 alkylene; heteroatom or carbonyl interrupted C 4 to C 24 alkenylene; heteroatom or carbonyl interrupted C 4 to C 14 arylene; or heteroatom or carbonyl interrupted C 5 to C 24 alkylarylene; and polymerizing said bis-acetal monomers upon addition of a catalyst to said polymerization mixture to form a polyacetal that is a polymer or copolymer of the structure:
where n is on average greater than 10.
2. The method of claim 1 , wherein said bis-acetal monomer is provided in situ by providing a plurality of diols of the structure:
and an acetal of the structure:
wherein said bis-acetal monomer is formed by alkoxymethylation and the polyacetal is formed without the isolation of a bis-acetal monomer.
3. The method of claim 1 , wherein said polymerization mixture further comprises a solvent.
4. The method of claim 1 , wherein said catalyst comprises a protonic acid, Lewis acid, metal oxyhalide, or metal sulfate.
5. The method of claim 4 , wherein said protonic acid comprises toluene sulfonic acid.
6. The method of claim 1 , wherein said polyacetal is a copolymer of two or more acetal repeating units.
7. The method of claim 1 , further comprising an end-capping unit comprising at least one functionality for polymerization that is unreactive with an acetal functionality and one acetal functionality of the structure:
R′ x OCH 2 O—
where R′ is C 1 to C 5 alkyl.
8. The method of claim 1 , further comprising a non-acetal polymer comprising one or more acetal functionality and one acetal functionality of the structure:
R′ x OCH 2 O—
where R′ is C 1 to C 5 alkyl, wherein the non-acetal polymer comprises a block of a block copolymer with the polyacetal being a second block.
9. A polyacetal comprising the structure:
wherein R′ is independently C 1 to C 5 alkyl, n is on average greater than 10, and R is one or more linear, branched or cyclic: C 5 to C 24 alkylene; C 4 to C 24 alkenylene; C 6 to C 14 arylene; C 7 to C 24 alkylarylene; heteroatom or carbonyl interrupted C 4 to C 24 alkylene where the heteroatom is O or S; heteroatom or carbonyl interrupted C 4 to C 24 alkenylene where the heteroatom is O or S; heteroatom or carbonyl interrupted C 4 to C 14 arylene where the heteroatom is O or S; and/or heteroatom or carbonyl interrupted C 5 to C 24 alkylarylene where the heteroatom is O or S.
10. The polyacetal of claim 9 , wherein the R groups are selected from linear C 5 to C 24 alkylenes.
11. The polyacetal of claim 9 , further comprising an end-capping unit comprising a functionality for polymerization that is unreactive with an acetal functionality.
12. The polyacetal of claim 9 , further comprising an end-capping unit comprising at least one functionality for polymerization that is unreactive with an acetal functionality.
13. The polyacetal of claim 9 , further comprising a block of a non-acetal polymer.