Making polymer chemistry 'click'
by Staff Writers
Berkeley CA (SPX) Jul 27, 2017
A team of researchers has developed a faster and easier way to make sulfur-containing polymers that will lower the cost of large-scale production. The achievement, published in Nature Chemistry and Angewandte Chemie, opens the door to creating new products from this class of polymers while producing far less hazardous waste.
The researchers' reaction technique, dubbed SuFEx for sulfur(VI) fluoride exchange, combined with a newly identified class of catalysts that speed up the reactions, could be used to make everything from water bottles and mobile phone cases to medical devices and bulletproof glass.
When a useful molecule is discovered, there are few reactions that chemists can use that are simple and efficient enough to meet the industrial production requirements for cost-effectively scaling up. In 2001, Nobel laureate K. Barry Sharpless introduced a new concept to organic chemistry known as "click chemistry," describing a suite of controllable, highly reactive reactions that are high-yielding and require little to no purification.
Following nature's example, click reactions follow simple protocols, use readily available starting materials, and work under mild reaction conditions with benign starting reagents. Click chemistry has become a valuable tool for generating large libraries of potentially useful compounds as industries look to discover new drugs and materials.
Scientists at Lawrence Berkeley National Laboratory's (Berkeley Lab) Molecular Foundry, a facility that specializes in nanoscale science, worked with a team led by Sharpless and Peng Wu, professors at the Scripps Research Institute (TSRI). The team created long chains of linked sulfur-containing molecules, termed polysulfates and polysulfonates, using a SuFEx click reaction.
"Click chemistry is a powerful tool for materials discovery, but synthetic chemists are often not well-equipped to characterize the polymers they create," said Yi Liu, director of the Organic Synthesis facility at the Molecular Foundry. "We can provide a broad spectrum of expertise and instrumentation that can expand the scope and impact of their research."
The SuFEx reaction, introduced as a new family of click reactions in 2014, reliably and quickly creates new chemical bonds, connecting compounds together with sulfates or sulfonates. While polysulfates have shown great potential as competitors to polycarbonates (strong plastics used for eyewear lenses and water bottles, for example), they have been rarely used for industrial applications due to a lack of reliable and easily scalable synthetic processes.
To overcome the challenges of mass-manufacturing polysulfates and polysulfonates, the TSRI team explored various catalysts and starting reagents to optimize the SuFEx reaction. They relied on their collaborators at the Molecular Foundry to assess physical properties and determine if the newly created polymers were thermally stable products.
Polymers are assembled from smaller molecules - like stringing a repeating pattern of beads on a necklace. In creating a polysulfonate "necklace" with SuFEx, the researchers identified ethenesulfonyl fluoride-amine/aniline and bisphenol ether as good "beads" to use and found that using bifluoride salt as a catalyst made the previously slow reaction "click" into action. Researchers found that the high efficiency of the reaction results in a remarkable 99 percent conversion, from starting reactants to products, in less than an hour.
Researchers found that the new reaction requires 100 to 1,000 times less catalyst than other known methods, resulting in significantly less hazardous waste. Bifluoride salts are also much less corrosive than previously used catalysts, allowing for a wider range of starting substrate "beads," which researchers said they hope could lead to its adoption for a range of industrial processes.
"There are many new polymers that haven't been widely used by industry before," said Liu. "By reducing waste and improving product purity, we lower the cost and make this reaction much more industry friendly."
The Molecular Foundry is a DOE Office of Science User Facility that provides free access to state of the art equipment and multidisciplinary expertise in nanoscale science to visiting scientists from all over the world.
Nashville TN (SPX) Jul 25, 2017
Two-dimensional materials that can multitask. That is the result of a new process that naturally produces patterned monolayers that can act as a base for creating a wide variety of novel materials with dual optical, magnetic, catalytic or sensing capabilities. "Patterned materials open up the possibility of having two functionalities in a single material, such as catalyzing a chemica ... read more
Lawrence Berkeley National Laboratory
Space Technology News - Applications and Research
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"Kufanya kemia ya polima ""bonyeza"" na Waandishi wa Wafanyakazi Berkeley CA (SPX) Jul 27, 2017 ""Timu ya watafiti imebuni njia ya haraka na rahisi ya kutengeneza polima zenye sulfuri ambayo itapunguza gharama ya uzalishaji wa kiwango kikubwa." Ufanisi huo, uliochapishwa katika Nature Chemistry na Angewandte Chemie, unafungua mlango kwa ajili ya kuunda bidhaa mpya kutoka darasa hili la polima wakati wa kuzalisha taka hatari kidogo. Utafiti huo unaitwa Sufex (Sulfur Fluoride Exchange) na unajumuisha aina mpya ya kichocheo kinachoongeza kasi ya athari za kemikali, na inaweza kutumika kutengeneza kila kitu kutoka chupa za maji hadi vifaa vya matibabu na glasi zisizo na risasi. Wakati molekuli muhimu imegunduliwa, kuna athari chache ambazo wanakemia wanaweza kutumia ambazo ni rahisi na ufanisi wa kutosha kukidhi mahitaji ya uzalishaji wa viwanda kwa kuongeza gharama. "Mwaka wa 2001, K. Barry Sharpless, mshindi wa tuzo ya Nobel, alianzisha dhana mpya ya kemia ya kikaboni inayojulikana kama ""kimia ya click,"" ikielezea seti ya athari zinazoweza kudhibitiwa, zenye athari kubwa ambazo zinatoa matokeo ya juu na zinahitaji kusafishwa kidogo au hakuna." Kufuatia mfano wa asili, athari za bonyeza hufuata itifaki rahisi, hutumia vifaa vya kuanza vinavyopatikana kwa urahisi, na hufanya kazi chini ya hali ya athari laini na reagents za kuanza zisizo na madhara. "Kemia ya ""Click"" imekuwa chombo muhimu cha kutengeneza maktaba kubwa ya misombo yenye manufaa, wakati viwanda vinatafuta kugundua dawa mpya na vifaa." Wanasayansi wa Lawrence Berkeley National Laboratory (BRL) Molecular Foundry, kituo cha sayansi ya nanoscale, walifanya kazi na timu iliyoongozwa na Sharpless na Peng Wu, maprofesa katika Taasisi ya Utafiti ya Scripps. Timu hiyo ilitengeneza minyororo mirefu ya molekuli zenye sulfuri, zinazoitwa polysulfates na polysulfonates, kwa kutumia athari ya bonyeza ya SuFEx. "Kemia ya Click ni chombo chenye nguvu cha kugundua vifaa, lakini mara nyingi wanakemia wa synthetic hawajawa na vifaa vya kutosha kuelezea polima wanazotengeneza, ""alisema Yi Liu, mkurugenzi wa kituo cha Organic Synthesis katika Molecular Foundry." "Tunaweza kutoa utaalam na vifaa mbalimbali vinavyoweza kupanua upeo na athari za utafiti wao". SuFex ni aina ya athari ya kemikali ya kipekee ambayo hutengeneza viungo vipya vya kemikali na kuunganisha sulfates na sulfonates. Ingawa polysulphates wameonyesha uwezo mkubwa kama washindani wa polycarbonates (plastiki imara kutumika kwa lenses kioo na chupa za maji, kwa mfano), wao wamekuwa mara chache kutumika kwa ajili ya maombi ya viwanda kutokana na ukosefu wa kuaminika na urahisi scalable michakato synthetic. Ili kuepuka changamoto za utengenezaji wa wingi wa polysulphates na polysulfonates, timu ya TSRI ilichunguza vimeng'enya mbalimbali na reagents za kuanza ili kuboresha athari ya SuF-X. Walitegemea washirika wao katika Molecular Foundry kutathmini mali za kimwili na kuamua kama polima zilizotengenezwa hivi karibuni zilikuwa bidhaa thabiti za joto. Polima hufanyizwa kutokana na molekuli ndogo - kama vile nyuzi za shanga zinazorudiwa-rudiwa kwenye mkufu. Katika kuunda polysulfonate "mkufu" na SuFex, watafiti walitambua ethenesulfonyl fluoride-amine (ASF) na bisphenol ether (BFE) kama "beads" nzuri kutumia na kugundua kwamba kutumia chumvi ya bifluoride kama kichocheo alifanya awali polepole athari "click" katika hatua. Watafiti walipata kwamba ufanisi wa juu wa athari hiyo unasababisha mabadiliko ya 99% ya ajabu, kutoka kwa reagents ya kuanza hadi bidhaa, katika chini ya saa moja. Watafiti walipata kwamba athari mpya inahitaji catalyst mara 100 hadi 1,000 chini ya njia nyingine zinazojulikana, na kusababisha taka hatari kidogo. Bifluoride chumvi ni pia chini sana corrosive kuliko catalysts kutumika hapo awali, kuruhusu kwa ajili ya mbalimbali pana ya kuanza substrate "beads", ambayo watafiti alisema wanatarajia inaweza kusababisha kupitishwa kwa ajili ya mbalimbali ya michakato ya viwanda. "Kuna polima nyingi mpya ambazo hazijatumiwa sana na viwanda hapo awali", akasema Liu. "Kwa kupunguza taka na kuboresha usafi wa bidhaa, tunapunguza gharama na kufanya mmenyuko huu kuwa wa kirafiki zaidi kwa sekta". The Molecular Foundry ni ofisi ya DOE ya vifaa vya watumiaji wa sayansi ambayo hutoa upatikanaji wa bure wa vifaa vya kisasa na utaalam wa kitaaluma katika sayansi ya nanoscale kwa wanasayansi wanaotembelea kutoka kote ulimwenguni. "Nashville, Tennessee, Julai 25, 2017 ""Vitu viwili vya pande mbili vinavyoweza kufanya kazi nyingi.""" 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