AI helps chemists develop tougher plastics

Good news!

"Artificial intelligence is helping to develop tougher plastics: Using stress-responsive molecules identified by a machine-learning model, MIT chemists created polymers that are more resistant to tearing. This could lead to more durable plastics and cut down on plastic waste."

"A new strategy for strengthening polymer materials could lead to more durable plastics and cut down on plastic waste ...

Using machine learning, the researchers identified crosslinker molecules that can be added to polymer materials, allowing them to withstand more force before tearing. These crosslinkers belong to a class of molecules known as mechanophores, which change their shape or other properties in response to mechanical force. ...

The crosslinkers that the researchers identified in this study are iron-containing compounds known as ferrocenes, which until now had not been broadly explored for their potential as mechanophores. Experimentally evaluating a single mechanophore can take weeks, but the researchers showed that they could use a machine-learning model to dramatically speed up this process. ..."

From the abstract:

"Mechanophores are molecules that undergo chemical changes in response to mechanical force, offering unique opportunities in chemistry, materials science, and drug delivery. However, many potential mechanophores remain unexplored.

For example, ferrocenes are attractive targets as mechanophores due to their combination of high thermal stability and mechanochemical lability. However, the mechanochemical potential of ferrocene derivatives remains dramatically underexplored despite the synthesis of thousands of structurally diverse complexes. Herein, we report the computational, machine learning guided discovery of synthesizable ferrocene mechanophores. We identify over one hundred potential target ferrocene mechanophores with wide-ranging mechanochemical activity and use data-driven computational screening to identify a select number of promising complexes.

We highlight design principles to alter their mechanochemical activation, including regio-controlled transition state stabilization through bulky groups and a change in mechanism through noncovalent ligand–ligand interactions.

The computational screening is validated experimentally both at the polymer strand level through sonication experiments and at the network level, where a computationally discovered ferrocene mechanophore cross-linker leads to greater than 4-fold enhancement in material tearing energy.

This work establishes a generalizable framework for the high-throughput discovery and rational design of mechanophores and offers insights into structure–activity relationships in mechanically responsive materials."

AI helps chemists develop tougher plastics | MIT News | Massachusetts Institute of Technology "Researchers created polymers that are more resistant to tearing by incorporating stress-responsive molecules identified by a machine-learning model."

High-Throughput Discovery of Ferrocene Mechanophores with Enhanced Reactivity and Network Toughening (open access)

Graphical abstract

Figure 1. Screening procedure of the CSD curated data set of ferrocene complexes. Randomly sampled complexes are shown as cartoon renderings. Atoms are colored with hydrogen in white, carbon in gray, iron in dark orange, oxygen in red, nitrogen in blue, chlorine in green, and phosphorus in light orange.

Figure 3. Machine learning guided discovery of ferrocene mechanophores.

a, The maximum force distribution (violin plots) of the randomly selected unbridged (unbridged, green), randomly selected bridged (bridged, red) and machine learning selected (ML-unbridged, green) ferrocenes. ...

b, Classifier probability as a function of Fmax. Decision boundaries are shown as dashed lines. Correctly classified complexes are colored in green and incorrectly classified complexes are colored in red. ...

Plastic supercapacitors could solve energy storage problems

Good news!

Alert: New, more PFAS are coming and plastophobia is on the rise! Caution: Satire!

"Key takeaways

• A type of plastic called PEDOT that can conduct electricity is currently used to protect the internal components of electronic devices from static electricity and in organic solar cells and electrochromic devices, but it also has the ability to store electric charge somewhat like a battery.
• UCLA chemists have created a new type of textured, fur-like PEDOT film with more surface area to store charge and built a supercapacitor with it that stored nearly ten times more charge than conventional PEDOT and lasted nearly 100,000 charging cycles.
• The advance could lead to supercapacitors that can meet some energy storage demands as the world transitions to renewable, sustainable energy production.

...

But in the 1970s, scientists accidentally discovered that some plastics can also conduct electricity. This finding revolutionized the field and opened the door to applications in electronics and energy storage. ...

UCLA chemists are addressing these challenges with an innovative method to control the morphology of PEDOT to grow nanofibers precisely. These nanofibers exhibit exceptional conductivity and expanded surface area, both of which are crucial for enhancing the energy storage capabilities of PEDOT. ..."

From the abstract:

"The development of commercially viable composite conducting polymer electrodes for energy storage is limited by the requirement of multiple and complex fabrication steps, low energy density, and poor cycling stability.

In this work, a straightforward, economical, single-step method is developed for creating densely packed nanostructured PEDOT/graphene composite material demonstrating its application as an electrode for supercapacitors. The electrode achieved the highest mass loading reported so far in the literature for composite vapor phase polymerized PEDOT/rGO using aqueous FeCl3 (25.2 mg cm−2), and displayed an ultrahigh areal capacitance of 4628.3 mF cm−2 at 0.5 mA cm−2. The symmetric two-electrode setup displayed an energy density of 169.3 µWh cm−2 and a 70% capacitance retention after 70 000 cycles, showcasing its exceptional performance and durability."

  

Plastic supercapacitors could solve energy storage problems | UCLA "New process grows PEDOT nanofibers with superior electrical conductivity and more surface area to store charge"

Direct Fabrication of 3D Electrodes Based on Graphene and Conducting Polymers for Supercapacitor Applications (no public access)

An example of how EDOT monomer vapors react with a droplet of graphene oxide and ferric chloride to form PEDOT nanofibers.

Car tires shed a quarter of all microplastics in the environment. Urgent action is needed. Really!

The daily alarmism and hysteria about plastics, microplastics, and nanoplastics goes on unabated!

More propaganda and demagoguery! The ulterior motive by this scientist is to obtain more funding for largely frivolous research!

Plus, the main component of car tires is not plastic, but rubber!

The first rubber tires were made in 1839 by Charles Goodyear!

If the abrasion particles of tires was so dangerous as claimed, then we would be already all dead by now!

Alert: Plastophobia is a serious disorder. Please seek immediate medical help! (Caution: satire)

"Every year, billions of vehicles worldwide shed an estimated 6 million tons of tire fragments. These tiny flakes of plastic, generated by the wear and tear of normal driving, eventually accumulate in the soil, in rivers and lakes, and even in our food. Researchers in South China recently found tire-derived chemicals in most human urine samples. ...

We urgently need to classify tire particles as a unique pollution category. In our recent international study, colleagues and I found that this approach would drive more focused research that could inform policies specifically designed to mitigate tire pollution. And it could help ordinary people better understand the scale of the problem and what they can do about it. ..."

From the abstract:

"Concerns over the ecological impacts of urban road runoff have increased, partly due to recent research into the harmful impacts of tire particles and their chemical leachates. This study aimed to help the community of researchers, regulators and policy advisers in scoping out the priority areas for further study. To improve our understanding of these issues an interdisciplinary, international network consisting of experts (United Kingdom, Norway, United States, Australia, South Korea, Finland, Austria, China and Canada) was formed. We synthesised the current state of the knowledge and highlighted priority research areas for tire particles (in their different forms) and their leachates. Ten priority research questions with high importance were identified under four themes (environmental presence and detection; chemicals of concern; biotic impacts; mitigation and regulation). The priority research questions include the importance of increasing the understanding of the fate and transport of these contaminants; better alignment of toxicity studies; obtaining the holistic understanding of the impacts; and risks they pose across different ecosystem services. These issues have to be addressed globally for a sustainable solution. We highlight how the establishment of the intergovernmental science-policy panel on chemicals, waste, and pollution prevention could further address these issues on a global level through coordinated knowledge transfer of car tire research and regulation. We hope that the outputs from this research paper will reduce scientific uncertainty in assessing and managing environmental risks from TP and their leachates and aid any potential future policy and regulatory development."

Car tires shed a quarter of all microplastics in the environment. Urgent action is needed

Priorities to inform research on tire particles and their chemical leachates: A collective perspective

Charles Goodyear (December 29, 1800 – July 1, 1860) Poor Mr. Goodyear, he is scratching his head in his grave.

How do bulletproof vests work?

Recommendable!

Much less plastic in the oceans

Alarmism and hysteria based on severely inflated data (or a very crude estimate)! No surprise!

Plastophobia is a serious disease, please seek immediate medical help!

"... To date, the total amount of plastic in the ocean has been estimated at more than 25 million tons. This figure is derived from the assumption that 1 percent of the total amount of plastic in the ocean floats on the ocean surface, which is estimated to be a quarter of a million tons. The new study shows that the amount of plastic on the ocean surface is much higher, at about 2 million tons, but only one million tons is present in the deeper ocean (this excludes the amount of plastic on the bottom of the ocean). Thus, the total amount of plastic in the ocean is much lower, and the proportion floating on the surface relatively large.

Moreover, much less new plastic ends up in the ocean per year than previously believed: half a million tons instead of 4 to 12 million. The numbers show enormous differences. According to lead author ... this shows that research on plastic in the ocean is in its infancy. "We are really still looking for order of magnitude," ..."

From the abstract:

"The fate of plastics that enter the ocean is a longstanding puzzle. Recent estimates of the oceanic input of plastic are one to two orders of magnitude larger than the amount measured floating at the surface. This discrepancy could be due to overestimation of input estimates, processes removing plastic from the surface ocean or fragmentation and degradation. Here we present a 3D global marine mass budget of buoyant plastics that resolves this discrepancy. We assimilate observational data from different marine reservoirs, including coastlines, the ocean surface, and the deep ocean, into a numerical model, considering particle sizes of 0.1–1,600.0 mm. We find that larger plastics (>25 mm) contribute to more than 95% of the initially buoyant marine plastic mass: 3,100 out of 3,200 kilotonnes for the year 2020. Our model estimates an ocean plastic input of about 500 kilotonnes per year, less than previous estimates. Together, our estimated total amount and annual input of buoyant marine plastic litter suggest there is no missing sink of marine plastic pollution. The results support higher residence times of plastics in the marine environment compared with previous model studies, in line with observational evidence. Long-lived plastic pollution in the world’s oceans, which our model suggests is continuing to increase, could negatively impact ecosystems without countermeasures and prevention strategies."

Less plastic in the ocean and easier to clean up Significantly less plastic is estimated to be present in the global ocean than scientists previously thought. This new insight results from calculations with a computer model that includes a record number of measurements and observations of plastic in the ocean. Also, a relatively large proportion of the plastic in the ocean consists of large pieces that are easier to clean up.  The study external link is part of Mikael Kaandorp's doctoral research at Utrecht University and appeared in the scientific journal Nature Geoscience today. 

Closing the marine plastic mass budget: Using observational data to inform numerical models (dissertation)

Global mass of buoyant marine plastics dominated by large long-lived debris (open access)

Surprise! Weaker bonds can make polymers stronger

Good news! Amazing stuff!

"... Working with a type of polymer known as polyacrylate elastomers, the researchers found that they could increase the materials’ resistance to tearing up to tenfold, simply by using a weaker type of crosslinker to join some of the polymer building blocks.

These rubber-like polymers are commonly used in car parts, and they are also often used as the “ink” for 3D-printed objects. The researchers are now exploring the possible expansion of this approach to other types of materials, such as rubber tires.

“If you could make a rubber tire 10 times more resistant to tearing, that could have a dramatic impact on the lifetime of the tire and on the amount of microplastic waste that breaks off,”  ..."

From the abstract:

"The mechanical properties of covalent polymer networks often arise from the permanent end-linking or cross-linking of polymer strands, and molecular linkers that break more easily would likely produce materials that require less energy to tear. We report that cyclobutane-based mechanophore cross-linkers that break through force-triggered cycloreversion lead to networks that are up to nine times as tough as conventional analogs. The response is attributed to a combination of long, strong primary polymer strands and cross-linker scission forces that are approximately fivefold smaller than control cross-linkers at the same timescales. The enhanced toughness comes without the hysteresis associated with noncovalent cross-linking, and it is observed in two different acrylate elastomers, in fatigue as well as constant displacement rate tension, and in a gel as well as elastomers."

Surprise! Weaker bonds can make polymers stronger | MIT News | Massachusetts Institute of Technology

Facile mechanochemical cycloreversion of polymer cross-linkers enhances tear resistance (no public access)

Nanoplastic Ingestion Causes Neurological Deficits. Really!

Until recently it was concerns about microplastics, now it is about nanoplastics! What is next?

I suppose then microplastics cause suffocation! I suspect another case of alarmism and hysteria! Plastophobia is a serious affliction, please seek medical attention immediately!

Nanoplastic Ingestion Causes Neurological Deficits | The Scientist Magazine® Small plastic particulates can induce inflammatory responses in the gut and brain, but removing them reverses this damage.

Newly discovered cold-adapted microbes digest plastic at low temperatures

Plastic waste management is a non issue! If anyone suffers from plastophobia, please seek immediate medical help!

"Swiss scientists have discovered new cold-adapted microorganisms that can degrade different types of plastic at temperatures lower than currently required. ...
Already, several [other] microorganisms that "eat" plastic have been discovered. These bacteria and fungi produce enzymes that break down the plastic, but when these enzymes are expanded to an industrial scale, they usually only work at temperatures above 86 °F (30 °C). ...

Each of the strains was assayed to assess its ability to digest non-biodegradable polyethylene (PE) and biodegradable polyester-polyurethane (PUR), as well as two commercially available biodegradable mixtures of polybutylene adipate terephthalate (PBAT) and polylactic acid (PLA).

The scientists found that at 59 °F, more than half (56%) of strains – 11 fungi and eight bacteria – digested PUR, and 14 fungi and three bacteria digested PBAT and PLA. None of the strains could digest PE, even after 126 days spent on the plastic. ..."

From the abstract:

"Increasing plastic production and the release of some plastic in to the environment highlight the need for circular plastic economy. Microorganisms have a great potential to enable a more sustainable plastic economy by biodegradation and enzymatic recycling of polymers. Temperature is a crucial parameter affecting biodegradation rates, but so far microbial plastic degradation has mostly been studied at temperatures above 20°C. Here, we isolated 34 cold-adapted microbial strains from the plastisphere using plastics buried in alpine and Arctic soils during laboratory incubations as well as plastics collected directly from Arctic terrestrial environments. We tested their ability to degrade, at 15°C, conventional polyethylene (PE) and the biodegradable plastics polyester-polyurethane (PUR; Impranil®); ecovio® and BI-OPL, two commercial plastic films made of polybutylene adipate-co-terephthalate (PBAT) and polylactic acid (PLA); pure PBAT; and pure PLA. Agar clearing tests indicated that 19 strains had the ability to degrade the dispersed PUR. Weight-loss analysis showed degradation of the polyester plastic films ecovio® and BI-OPL by 12 and 5 strains, respectively, whereas no strain was able to break down PE. NMR analysis revealed significant mass reduction of the PBAT and PLA components in the biodegradable plastic films by 8 and 7 strains, respectively. Co-hydrolysis experiments with a polymer-embedded fluorogenic probe revealed the potential of many strains to depolymerize PBAT. Neodevriesia and Lachnellula strains were able to degrade all the tested biodegradable plastic materials, making these strains especially promising for future applications. Further, the composition of the culturing medium strongly affected the microbial plastic degradation, with different strains having different optimal conditions. In our study we discovered many novel microbial taxa with the ability to break down biodegradable plastic films, dispersed PUR, and PBAT, providing a strong foundation to underline the role of biodegradable polymers in a circular plastic economy."

Newly discovered cold-adapted microbes digest plastic at low temperatures

Plastic gobblers found in alpine and arctic soils Scientists at the Swiss Federal Institute for Forest, Snow and Landscape Research WSL have discovered microbes that degrade plastic at cool temperatures. This opens up new perspectives for recycling certain types of plastic. Most known microbes require at least 30°C for their decomposition work.

Discovery of plastic-degrading microbial strains isolated from the alpine and Arctic terrestrial plastisphere (open access)

Under the microscope the decomposition work by the microbes is visible on this biodegradable plastic foil.

Chart of the day

Looks like Western countries are hardly to blame, except for their massive exports of plastic waste to developing countries!

Alert: Plastophobia is a serious disease. Please seek immediate medical attention! (Caution: satire)

"... One river alone, the Pasig in the Philippines, is responsible for 6.4 percent of the waste that enters the world’s oceans through rivers ...
After all, Europe in particular is literally exporting its plastic problem. In 2019 alone, the EU exported 1.5 million metric tons of plastic waste to developing countries, which are clearly overburdened with the task of recycling and recovering such masses. ..."

Source: Where to Go with the Mountains of Plastic?

New supramolecular plastic heals itself in an instant and it is highly biodegradable

Human ingenuity will take care of the plastics issue! If you suffer from plastophobia, please seek help immediately!

There is no need for any Western governments nor the European Union to prohibit plastics or microplastics! 

"Scientists experimenting with next-generation plastics at Finland's University of Turku have developed a form of the material with some impressive capabilities, most notably an ability to quickly break down after use. The eco-friendly "supramolecular" plastic is therefore highly recyclable and, with careful tuning of its water content, can be turned into an adhesive or even instantly self-heal when damaged. ..."

From the abstract:

"Plastics are one of the most widely used polymeric materials. However, they are often undegradable and non-recyclable due to the very stable covalent bonds of macromolecules, causing environmental pollution and health problems. Here, we report that liquid-liquid phase separation (LLPS) could drive the formation of robust, stable, and sustainable plastics using small molecules. The LLPS process could sequester and concentrate solutes, strengthen the non-covalent association between molecules and produce a bulk material whose property was highly related to the encapsulated water amounts. It was a robust plastic with a remarkable Young’s modulus of 139.5 MPa when the water content was low while became adhesive and could instantly self-heal with more absorbed water. Finally, responsiveness enabled the material highly recyclable. This work allowed us to understand the LLPS at the molecular level and demonstrated that LLPS is a promising approach to exploring eco-friendly supramolecular plastics that are potential substitutes for conventional polymers."

New supramolecular plastic heals itself in an instant

Researchers create new, unparallelled supramolecular plastic which is degradable and highly recyclable A research group headed by senior researcher Jianwei Li at the MediCity Research Laboratory has explored a new type of materials called supramolecular plastics that would substitute the conventional polymeric plastics with an eco-friendlier material promoting sustainable development. The mechanical properties of the supramolecular plastic created by the researchers using liquid-liquid phase separation were comparable to conventional polymers, but the new plastic decomposes much more easily and would be easier to reuse.

Small Molecule-based Supramolecular Plastics Mediated by Liquid-Liquid Phase Separation (open access)