Discover – or create your own – sustainable materials with the Materials Library

Sustainability is a focal concern of the Penn Libraries' growing Materials Library collection. Designers of all backgrounds are increasingly interested in sustainable materials whether used in our homes, the clothing we wear, or the components of the objects that surround us. A visit to the Materials Library quickly reveals the complexities of truly sustainable materials and the innovative solutions that will help curb future contributions to climate change.

The built environment shapes the way humans experience the world. Perhaps less apparent are the vast number of resources used to construct these spaces. Something as globally utilized as concrete may appear innocuous, but the reality is that the concrete industry accounts for an estimated 8% of global carbon dioxide emissions. Cement is the component of concrete that accounts for the lion's share of emissions. Carbon dioxide is produced by the energy used to fire cement’s material components, like limestone, and the chemical reactions that occur during the heating process. The resulting cement is mixed with an aggregate — often stone or sand extracted from the earth — and water to form the concrete seen in buildings across regions and styles today.

Despite these challenges, there are concrete solutions that chip away at the environmental harms of this material. One is a carbon and calcium mixture called Biocement. It is combined with 85% natural aggregate and grown with microorganisms in ambient temperatures to form Biolith precast tiles with qualities like concrete. Production of these grown tiles notably reduces the energy costs of traditional concrete materials. Another answer to the concrete problem involves reducing the amount of earthen aggregate contained in the mix. Civil engineer Riyadh Al-Ameri developed a concrete that mixes recycled plastic from dialysis treatments with traditional aggregate to offset the amount of stone extracted from the earth. These concrete samples exemplify the incremental nature of supplanting harmful materials in architectural design and beyond.

But buildings are made from more than just concrete, and many scientists are working to develop other kinds of entirely new, sustainable building materials. One curious example that gets a lot of questions from Materials Library visitors is our salt pup made from salt and starch. The structure is a prototype from Eric Geboers' The Salt Project,  where seawater is converted into a desert building material as an agricultural byproduct using sun energy. The premise is that seawater is pumped into arid areas where the sun's energy distills fresh water for agricultural use. The salt that remains is mixed with starch before it is cast or 3D printed into its final form. The dried material is sealed to protect it from moisture, and the resulting structure is said to be as strong as rammed earth and traditional masonry.

Concerns around sustainability have translated into a range of different recycled bricks made from waste as well. The company Interstyle Glass Tiles takes recycled glass and fuses it into translucent bricks using a kiln. Other companies like Kenoteq are converting construction waste into bricks for future construction. Their K-Briq is an unfired building brick made from 90% construction waste to reduce that industry's impact on the environment. Half of unrecycled construction waste comes from drywall or sheetrock, a building material made from the mined mineral gypsum. Gypsum emits a noxious gas when broken down by bacteria in the landfill. This is why the Drywall Waste Brick (DWB) developed by a team at Washington State University is made from 80% drywall waste and an industrial by-product binder as a cheaper way to recycle this mineral-based material. The resulting DWB brick is a lightweight, waterproof brick.

Some innovations in the building sector make use of renewable materials that can be grown and replenished over time. One curious application of sustainable design lies between our walls and acoustical padding in interior spaces, better known as insulation. Gramitherm is a renewable thermal insulation made from raw grass cellulose fibers that buffers outside temperatures and absorbs sound. One acre of land can produce around 200 cubic meters of insulation! Even seagrass can be used for a more sustainable insulation that takes advantage of the organic materials naturally occurring fire retardance. Meanwhile, other companies are spinning up alternative insulations like Thermafleece, made from wool mixed with recycled fibers, or like UltraTouch Denim Insulation, made with upcycled textile waste.

There is no silver bullet that removes all the harms that building materials cause, and the same is true for the innovations in biobased polymers. For instance, did you know that it is possible to synthesize potato starch into a polymer chain that can be used as a plastic bag? BiologiQ’s Eco Starch Resin is a thermoplastic resin that comes in pellet form like traditional petroleum-based plastics, but this bioplastic is biodegradable with the introduction of water, bacteria, or other microorganisms. Potatoes can also be turned into Great Wrap, a cling wrap alternative to the traditional plastic version, that is home compostable in under 180 days.

Those potato starch plastics are a lot flimsier than what we use for a water bottle or even a button, but that doesn't mean there aren't renewable plastic alternatives that fill this niche. This is where milk buttons come into play. You read that right. Codelite buttons from Courtney & Co. are made from the casein protein in milk which can be formed into sheets or rods for fabrication. While this may sound cutting edge, the process of making casein into a pseudo-plastic was first patented in 1899 and used for buttons, cutlery handles, and knitting needles in the United Kingdom as early as 1910. Who needs plastic buttons that hang around for hundreds of years when you can have biodegradable milk buttons?

If you thought milk buttons were out there, then get ready for a shirt made from milk waste. The Mi Terro recycled milk waste T-shirt utilizes spoiled milk that cannot be consumed. The production of this upcycled waste material uses 60% less water than a cotton shirt, and every five shirts divert one glass of milk from going to a landfill. Visitors to the Materials Library often ask if the shirt has a foul odor (it doesn't) and are shocked to feel how soft the fabric is. Even better, the shirt is anti-microbial and moisture-wicking while being much more eco-friendly than traditional shirts that boast these qualities.

The fashion industry is a behemoth of environmental issues that we can only scratch the surface of here. You've read how milk could be used for our shirts and buttons, but what else? The Degenerate shoe from Unless is made entirely of plants that can be chopped up when the sole has worn through and returned to the soil, but it looks like a regular skate shoe. This company uses milk buttons mentioned in some of their apparel, too, to highlight that these sustainable materials do not exist in a vacuum.

Then there is the world of leathers. Traditional leather is laden with chemicals and vegan alternatives use petroleum products to emulate animal skins. This realm is a spectrum of good and better sustainable solutions; much like concrete, there is no one material to fully supplant animal leathers. However, companies like Desserto are creating cactus leathers backed in a cotton-polyester blend fabric that is free of herbicides, pesticides, phthalates, and PVC. Growing the cacti relies on rainwater and earth minerals, while the drying process takes advantage of the sun to eliminate added energy costs, resources, and specialized machinery. Fruitleather Rotterdam in the Netherlands is making another vegan leather with mangoes and natural resins that has a pleasantly sweet, fruity scent to it. Both samples are shockingly soft and flexible, like you expect with traditional leathers, but can be produced with a fraction of the resources it takes to raise an animal, slaughter it, and tan its hide.

All of the sustainable items mentioned here are accessible for interaction and study through the Materials Library by appointment. The collection houses over 9,000 different material samples that possess varying degrees of sustainable, renewable, or otherwise environmentally friendly origins beyond the limited scope of architecture, fashion, and plastics as described here. No matter what you are studying, the Materials Library probably has something to offer, so don’t hesitate to contact us.

Featured image: Clockwise from top left are the salt pup, milk buttons, vegan cactus leather, and denim insulation.