Block Copolymers Based on Linear Poly(oxymethylene)(POM) and Hyperbranched Poly(glycerol): Combining Polyacetals with Polyethers
Synthesis of hyperbranched-linear-hyperbranched ABA triblock copolymers based on linear poly(oxy methylene) (POM) and hyperbranched poly(glycerol) (hbPG) blocks is described. The polymers having a polyacetal polyether structure were prepared from linear bishydroxy functional POM macroinititators, obtained by cationic ring-opening polymerization of trioxane and dioxane with formic acid as transfer agent and following hydrolysis of the formiate group. Partial deprotonation of the resulting hydroxyl groups permitted the hypergrafting by anionic ring-opening multibranching polymerization (ROMBP) of glycidol.
1 . A polymer comprising a hyperbranched polyoxymethylene homopolymer or copolymer, the polyoxymethylene homopolymer or copolymer comprising a middle portion positioned between a first end portion and a second end portion, at least one of the end portions having a hyperbranched structure.
2 . A polymer as defined in claim 1 , wherein both end portions have a hyperbranched structure.
3 . A polymer as defined in claim 1 , wherein the middle portion comprises a linear structure having repeating oxymethylene units and optionally other oxyalkylene units.
4 . A polymer as defined in claim 1 , wherein the hyperbranched polyoxymethylene polymer comprises a triblock copolymer.
5 . A polymer as defined in claim 1 , wherein each hyperbranched portion includes at least 10 branches per molecule and generally less than about 500 branches per molecule.
6 . A polymer as defined in claim 1 , wherein each hyperbranched portion includes end units and wherein the end units comprise functional groups.
7 . A polymer as defined in claim 6 , wherein at least about 80% of the end units comprise the functional groups.
8 . A polymer as defined in claim 6 , wherein the functional groups comprise hydroxyl groups, amino groups, alkoxyl groups, esters or amides.
9 . A polymer as defined in claim 1 , wherein the hyperbranched portions are aliphatic.
10 . A polymer as defined in claim 1 , wherein the hyperbranched portions include ether linkages.
11 . A polymer as defined in claim 1 , wherein the hyperbranched portions comprise hyperbranched polyglycerol.
12 . A polymer as defined in claim 1 , wherein the polymer is amphiphilic.
13 . A process for producing a hyperbranched polyoxymethylene polymer comprising:
at least partially deprotonating hydroxy terminal groups on a polyoxymethylene polymer or oligomer;
reacting the deprotonated polyoxymethylene polymer or oligomer with a multi-functional hyperbranching monomer, the multi-functional hyperbranching monomer grafting to the polymer or oligomer and further polymerizing to form a polyoxymethylene polymer with a hyperbranched portion.
14 . A process as defined in claim 13 , wherein the polyoxymethylene polymer or oligomer comprises a bishydroxy polyoxymethylene.
15 . A process as defined in claim 13 , wherein the polyoxymethylene polymer or oligomer is deprotonated by contacting with a base, while removing water.
16 . A process as defined in claim 15 , wherein the base comprises a hydroxide, such as cesium hydroxide, potassium hydroxide, sodium hydroxide, or mixtures thereof.
17 . A process according to claim 13 , wherein the polyoxymethylene polymer or oligomer has a linear structure.
18 . A process according to claim 13 , wherein the resulting polyoxymethylene polymer with a hyperbranched portion comprises a triblock copolymer.
19 . A process as defined in claim 18 , wherein the triblock copolymer includes a polyoxymethylene block positioned in between two hyperbranched blocks.
20 . A process according to claim 13 , wherein the multi-functional hyperbranching monomer comprises glycidol.
21 . A process as defined in claim 20 , wherein the polyoxymethylene polymer with a hyperbranched portion is produced through hypergrafting by anionic ring-opening multi-branching polymerization.
22 . A process according to claim 13 , wherein the weight ratio of the deprotonated polyoxymethylene polymer or oligomer to the multi-functional hyperbranching monomer is from about 1:0.1 to about 1:10.