摘要:
A method is provided for carrying out depolymerization of a polymer containing electrophilic linkages in the presence of a catalyst and a nucleophilic reagent, wherein production of undesirable byproducts resulting from polymer degradation is minimized. The reaction can be carried out at a temperature of 80° C. or less, and generally involves the use of an organic, nonmetallic catalyst, thereby ensuring that the depolymerization product(s) are substantially free of metal contaminants. In an exemplary depolymerization method, the catalyst is a carbene compound such as an N-heterocyclic carbene, or is a precursor to a carbene compound. The method provides an important alternative to current recycling techniques such as those used in the degradation of polyesters, polyamides, and the like.
摘要:
A method is disclosed for providing a patterned surface wherein predetermined regions of the surface are masked with a self-assembled monolayer (“SAM”) covalently bound to a brush polymer overlayer. The remainder of the substrate surface will generally be functionalized with a second self-assembled monolayer. Preferably, the method involves a microcontact printing technique, wherein a molecular moiety capable of spontaneously forming an SAM upon transfer to a surface is “stamped” onto a substrate surface, followed by growth (or covalent attachment) of a polymer on exposed functional groups within the SAM molecules. Coverage of surface regions with both an SAM and a polymer overlayer provides a number of advantages, particularly with regard to surface masking during etching and the like. The method is useful in the manufacture of microelectronic circuitry, biosensors, high-density assay plates, and the like.
摘要:
A branched radial block copolymer including the reaction product of a dendritic macromolecular initiator, and one or more chain extending monomers.
摘要:
The present invention relates to an electronic device for distributing electrical signals between electronic elements comprising a dielectric foamed thermoset polymer having a plurality of electrical circuits.
摘要:
A method comprises forming a reaction mixture comprising a terephthalate polyester, a glycol comprising 2 to 5 carbons, and an amidine organocatalyst; and heating the reaction mixture at a temperature of about 120° C. or more to depolymerize the terephthalate polyester, thereby forming a terephthalate reaction product comprising a monomeric dihydroxy terephthalate diester; wherein the terephthalate reaction product contains terephthalate oligomers in an amount less than the amount of terephthalate oligomers that would result from i) substituting the amidine organocatalyst with an equimolar amount of a guanidine catalyst and ii) depolymerizing the terephthalate polyester under otherwise identical reaction conditions.
摘要:
A covalently crosslinked hydrogel comprises a) three or more divalent poly(alkylene oxide) chains P′ covalently linked at respective first end units to a branched first core group C′, b) three or more divalent poly(alkylene oxide) chains P″ covalently linked at respective first end units to a branched second core group C″, the chains P″ comprising respective second end units which are covalently linked to between 0% and 100% of respective second end units of chains P′ by divalent linking groups L″, and c) at least one pendant cationic block copolymer chain A′-B′. A′-B′ comprises i) a divalent block A′ comprising a poly(alkylene oxide) backbone chain having an end unit covalently linked to a second end unit of one of the chains P′ by a divalent linking group L′, and ii) a monovalent block B′ comprising a first repeat unit, the first repeat unit comprising a backbone carbonate group and a cationic side chain group.
摘要:
A one pot method of preparing cyclic carbonyl compounds comprising an active pendant pentafluorophenyl ester group is disclosed. The cyclic carbonyl compounds can be polymerized by ring opening methods to form ROP polymers comprising repeat units comprising a side chain pentafluorophenyl ester group. Using a suitable nucleophile, the pendant pentafluorophenyl ester group can be selectively transformed into a variety of other functional groups before or after the ring opening polymerization.
摘要:
The disclosure relates to methods and materials useful for depolymerizing a polymer. In one embodiment, for example, the disclosure provides a method for depolymerizing a polymer containing electrophilic linkages, wherein the method comprises contacting the polymer with a nucleophilic reagent in the presence of a guanidine-containing compound. The methods and materials of the disclosure find utility, for example, in the field of waste reclamation and recycling.
摘要:
A cationic star polymer is disclosed of the general formula (1): I′P′]w′ (1), wherein w′ is a positive number greater than or equal to 3, I′ is a dendritic polyester core covalently linked to w′ independent peripheral linear cationic polymer chains P′. Each of the chains P′ comprises a cationic repeat unit comprising i) a backbone functional group selected from the group consisting of aliphatic carbonates, aliphatic esters, aliphatic carbamates, aliphatic ureas, aliphatic thiocarbamates, aliphatic dithiocarbonates, and combinations thereof, and ii) a side chain comprising a quaternary amine group. The quaternary amine group comprises a divalent methylene group directly covalently linked to i) a positive charged nitrogen and ii) an aromatic ring.
摘要:
A method comprises forming a reaction mixture comprising a terephthalate polyester, a glycol comprising 2 to 5 carbons, and an amidine organocatalyst; and heating the reaction mixture at a temperature of about 120° C. or more to depolymerize the terephthalate polyester, thereby forming a terephthalate reaction product comprising a monomeric dihydroxy terephthalate diester; wherein the terephthalate reaction product contains terephthalate oligomers in an amount less than the amount of terephthalate oligomers that would result from i) substituting the amidine organocatalyst with an equimolar amount of a guanidine catalyst and ii) depolymerizing the terephthalate polyester under otherwise identical reaction conditions.