KRICT Develops 4D Printed Sulfur Polymers for Soft Robotics

From Oil Refining Byproduct to Advanced Robotics

Researchers at the Korea Research Institute of Chemical Technology (KRICT) have developed a new 4D printing technology that transforms sulfur — a byproduct of oil refining — into smart materials with shape memory capabilities for soft robotics.

The innovation addresses a long-standing challenge with sulfur plastics: their internal net-like structure creates low fluidity, limiting their applications. The KRICT team solved this by precisely controlling sulfur content and polymer structure to create printable materials.

How It Works

The researchers developed a method to make sulfur plastics printable by loosening their internal entangled structure. The 4D printing technology enables "shape memory" — where the material changes shape in response to stimuli like temperature or light.

Key breakthrough: using a special laser, the team bonded material pieces together in just 8 seconds without adhesive. They also created a soft robot smaller than 1 centimeter by mixing 20% iron powder into the sulfur plastic — the robot moves autonomously without external power.

Why This Matters

Lead researcher Kim explained: "This study is the first case of upcycling sulfur, an industrial byproduct, into an advanced robotic material. Smart materials that can move on their own and be recycled will become a key driver of future soft robotics and automation industries."

Sulfur is discarded in large quantities from oil refining processes. This research provides a pathway to transform this waste into high-value materials — a win for both economics and sustainability.

Future Applications

The combination of 4D printing, shape memory, and self-powered movement opens possibilities for:

• Medical devices that respond to body temperature
• Self-assembling structures
• biodegradable soft robots
• Industrial sensors

The findings were published in Advanced Materials in November 2025.