---
title: "Korean researchers turn petroleum refining waste into 4D printed soft robotics"
url: https://www.voxelmatters.com/korean-researchers-turn-petroleum-refining-waste-into-4d-printed-soft-robotics/
date: 2026-03-16
modified: 2026-03-16
lang: en
author: "Tess Boissonneault"
description: "The crude oil refining process generates substantial waste and by-products such as elemental sulfur, which is typically converted into sulfuric acid and used as a fertilizer. However, we are at..."
categories:
  - "3D Printing Processes"
  - "Research & Education"
  - "Robotics"
  - "Sustainability"
tags:
  - "future"
image: https://www.voxelmatters.com/wp-content/uploads/2026/03/krict-4d-printing-1-640x394.jpeg
word_count: 632
---

# Korean researchers turn petroleum refining waste into 4D printed soft robotics

The crude oil refining process generates substantial waste and by-products such as elemental sulfur, which is typically converted into sulfuric acid and used as a fertilizer. However, we are at a point where the volume of this petroleum refining by-product is in oversupply—for perspective, 85 million tons of sulfur by-product were generated in 2024—so it is critical to find alternative and sustainable uses for it.

While fertilizer remains the dominant application for sulfur waste, there are other avenues that are showing considerable promise, including "sulfur plastics", which effectively turn the waste stream into usable, high-value manufacturing materials. A team of researchers from the Korea Research Institute of Chemical Technology (KRICT) has been working with sulfur plastics and exploring the potential of fabricating them as self-actuating robotic structures using a special 4D printing process.

4D printing is an emerging additive manufacturing subsegment—largely still limited to research applications—that involves 3D printing an object that is engineered to transform into a different shape when triggered by something, such as time, heat, moisture, etc. For example, a research group based out of Spain recently developed a 4D multi-material printing process for creating PETG and PVA structures that degrade when exposed to water, something that could have applications in [adaptive medical implants](https://www.voxelmatters.com/researchers-develop-degradable-4d-printed-actuators-using-petg-and-pva/) and soft robotics.

[![Korean researchers turn sulfur waste into 4D printed soft robotics](https://www.voxelmatters.com/wp-content/uploads/2026/03/krict-4d-printing-3.jpeg)](https://www.voxelmatters.com/wp-content/uploads/2026/03/krict-4d-printing-3.jpeg)(Image: KRICT)

The team at KRICT, for its part, is making progress in the printing of sulfur-rich plastics that can change based on heat, light, and magnetic fields. The team, which is led by Dr. Dong-Gyun Kim from KRICT, Professor Jeong Jae Wie of Hanyang University, and Professor Yong Seok Kim of Sejong University, reports that its 4D printing process is the first of its kind.

According to the researchers, sulfur plastics integrate a number of unique and beneficial properties, including the ability to transmit infrared light and capture heavy metals. These properties open up doors for the materials to be used for infrared camera lenses and water purification systems, among others. Moreover, the plastics are recyclable, which has established them as eco-friendly materials that enable more circular production.

The trouble with sulfur plastics up to this point, however, has been the ability to easily 3D print them. That is, the polymers are characterized by a dense cross-linked internal composition that results in low flowability that is not conducive to 3D printing. To overcome this, the research team had to develop a more loosely cross-linked sulfur polymer structure, which would facilitate extrusion.

[![Korean researchers turn sulfur waste into 4D printed soft robotics](https://www.voxelmatters.com/wp-content/uploads/2026/03/krict-4d-printing-2.jpeg)](https://www.voxelmatters.com/wp-content/uploads/2026/03/krict-4d-printing-2.jpeg)(Image: KRICT)

As the team has demonstrated in [a study published in *Advanced Materials*](https://advanced.onlinelibrary.wiley.com/doi/10.1002/adma.202507057), the resulting material is a sulfur plastic with a closely controlled cross-linked network that can printed into objects with shape-memory properties. This means that when exposed to heat or light, the printed objects change shape autonomously. Moreover, if the printed structures are exposed to a near-infrared (NIR) laser for just eight seconds, it is possible to chemically weld parts together. As the team says, this means that separate printed parts can be joined without adhesives, enabling the construction of complex LEGO-like structures.

In the study, sulfur plastic was also embedded with 20% magnetic particles, which enabled the team to develop tiny (<1 cm) soft robots that could move without any external power source. These printed robots could actually realize rather complex motions based on magnetic fields applied. A final, and highly notable, benefit is that the printed material can be fully recycled, simply by melting down the plastic and reusing it as feedstock. This could make the production of self-actuating soft robotics far more ecological.

Dr. Dong-Gyun Kim said of the project: "This study represents the first example of upcycling industrial sulfur waste into advanced robotic materials. Smart materials that can move autonomously and be recycled are expected to become key drivers of future soft robotics and automation technologies."