Dendron, polyurethane with side-chain regular dendron, and producing methods thereof
Methods for producing dendrons of different generations with hydrophobic functional end-groups, and for producing polyurethanes with the side-chain dendrons are disclosed step-by-step. The dendron with hydrophobic functional end-groups in the polyurethane systems, and the honeycomb-like structure thin films are obtained by a breath-figure process. The structures of dendrons and dendritic side-chain polyurethanes are respectively expressed in the following and the end-groups (R) of the dendron are long alkyl chains or perfluoroalkyl derivatives.
1. A process for producing a polyurethane with a side-chain regular dendron, formed in a two-stage reaction,
wherein the side-chain regular dendron is formed in a three-stage reaction including the following five steps:
(i) stage 1 reaction:
forming a first solution by dissolving bifunctional build unit IDD in tetrahydrofuran, adding alcohol into the first solution at 70° C. with aerating nitrogen of gas for 4 hours, dropping the first solution into a methanol for precipitation and stirring at 70° C. for 6 hours, and
obtaining a first intermediate by collecting a first product with exhaust filtering and drying;
(ii) stage 2 reaction:
forming a second solution by dissolving the first intermediate in dehydrated tetrahydrofuran,
aerating nitrogen of gas,
stirring the second solution and slowly adding diethylenetriamine at 70° C., keeping in reaction for 3 hours after a second product starts being precipitated,
cooling the second solution to room temperature,
washing the second product with mass tetrahydrofuran,
obtaining a dendrimer by drying the second product with exhaust filtering;
(iii) stage 3 reaction:
forming a third solution by mixing the dendrimer with dehydrated tetrahydrofuran, stirring the third solution with aerating nitrogen of gas at 75° C.,
after dissolving the dendrimer, adding the bifunctional build unit IDD in the third solution for reaction for 4 hours,
drawing part of the tetrahydrofuran,
dropping the third solution into methanol for precipitation,
obtaining a second intermediate by exhaust filtering and drying;
(iv) repeating the above steps to form a third intermediate and a fourth intermediate; and
(v) forming a fourth solution by dissolving the second intermediate, the third intermediate, and the fourth intermediate into dehydrated tetrahydrofuran and mixing with APDEA,
keeping the fourth solution in reaction under aerating nitrogen of gas at 75° C. for 48 hours,
after the intermediates are completely reacted, precipitating the fourth solution with methanol and washing incompletely-reacted APDEA out, and
obtaining the dendron by exhaust filtering and drying after stirring for 6 hours; and
the two-stage reaction, by which the polyurethane is formed, includes:
(I) a first stage reaction:
forming a reaction system by disposing purified R1 and dehydrated R2 in a flask at 60° C. with aerating nitrogen of gas, keeping the reaction system in circumference reaction for half an hour,
wherein R1 is one selected from an R1 group containing methylene di-p-phenyl diisocyanate (MDI), 1,6-hexamethylene diisocyanate (HDI), and isophorone diisocyanate (IPDI),
R2 is one selected from an R2 group containing polypropyl glycol (PPG), polycaprolactone (PCL), and polytetramethylene ether glycol (PTMEG), and
R1 is MDI, when R2 is PPG,
R1 is IPDI, when R2 is PPG,
R1 is MDI, when R2 is PCL, and
R1 is MDI, when R2 is PTMEG, with the first stage reaction followed by a second stage reaction;
(II) a second stage reaction:
adding into the reaction system, the dendron, as a chain extender, and dibutyltin dilaurate, as a catalyst,
heating the reaction system to 80° C. and in reaction for three-and-half hours, and pouring a solution in the reaction system onto a disk of Teflon disposed in an oven for removing solvent.