Amine-End Block Copolymers for Anion Exchange and Strength
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Solution Overview
Problem
There is a need for functionalized styrene block copolymers with modified characteristics to meet specific user and process goals, as existing amine-functionalized block copolymers do not fully address the requirements for anion exchange properties and mechanical performance.
Innovation Solution
A functionalized block copolymer is developed, comprising amino-functionalized end blocks and additional blocks with specific molecular weights and temperature properties, where the D block is formed on external ends, and the B block constitutes at least 75 wt% of the molecular weight, with the option to include hydrogenated conjugated diene segments, allowing for anion exchange properties and various applications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If amine functional groups are added to the polymer backbone to enhance anion exchange properties, then anion exchange capacity is improved, but mechanical performance deteriorates
Solution Approach 1:
The patent divides the block copolymer into distinct functional segments: amine-functionalized end blocks (D blocks) containing polymerized p-vinylbenzylamine units for anion exchange, and non-functionalized interior blocks (A and B blocks) comprising styrene and conjugated diene segments for mechanical integrity. This spatial segmentation allows the anion exchange functionality to be concentrated at the ends while the interior blocks maintain structural strength, resolving the contradiction between enhanced anion exchange capacity and preserved mechanical performance.
2Reliability
If amine functionalized blocks are placed in the interior of the block copolymer, then anion exchange properties are enhanced, but control over functional group distribution deteriorates
Solution Approach 1:
The patent employs asymmetric block copolymer architecture where amine-functionalized D blocks are positioned exclusively at the terminal ends of the copolymer chain, while non-functionalized A and B blocks occupy the interior positions. This asymmetric arrangement, achieved through controlled sequential polymerization, provides precise control over functional group distribution by ensuring all amine groups are located at the ends rather than being randomly distributed throughout the interior, thereby enhancing anion exchange properties while maintaining manufacturing precision.
3Stability of the object's composition
If conjugated diene segments are hydrogenated to improve chemical stability, then chemical stability is enhanced, but processing flexibility deteriorates
Solution Approach 1:
The patent applies local quality by selectively hydrogenating only the conjugated diene segments within the B blocks while leaving the styrene-rich A blocks and amine-functionalized D blocks unchanged. This localized modification confers chemical stability specifically to the diene-containing regions, which are most susceptible to degradation, while preserving the inherent processing flexibility of the non-hydrogenated styrene and amine-functionalized segments. The result is a block copolymer with enhanced overall chemical stability that retains adequate processing flexibility for membrane fabrication.
Data Source
AI summary
Disclosed herein is a functionalized block copolymer comprising (a) at least one end block D comprising on average at least one amino- or phosphino- functionalized polymer unit of formula (I) and one or more additional blocks selected from the group consisting of (b) one or more A blocks substantially free of amino- or phosphino- functional groups and having a number average molecular weight of from about 1,000 to about 60,000, and has a high service temperature, and (c) one or more B blocks, wherein each block B is essentially non-functionalized, has a number average molecular weight of from about 1,000 to about 1,000,000, and has a glass transition temperature of at most about 20°C, and (d) mixtures of one or more A blocks and one or more B blocks; wherein Z is nitrogen or phosphorus; R1 is hydrogen or alkyl; R2 is hydrogen or is tertiary alkyl; R each independently, is alkyl or phenyl optionally substituted by a moiety -(A1- NRa)xRb or -(A1-ORa)xRb; or two R groups, together with the Z to which they are bonded, form an optionally substituted ring; x is 1, 2 or 3; A1 is straight chain alkylene optionally substituted by one or more methyl and/or ethyl groups; and Ra and Rb, each independently, is hydrogen or alkyl; or a corresponding onium salt.