Year 9 Science · Unit 2 · Lesson 16
Challenge Worksheet
Learning Goals
What if…?
Scenario
Scientists at the University of Queensland develop a fully functional polymer with all the properties of polyethylene, flexible, waterproof, and cheap to produce, but made entirely from sugar cane monomers instead of ethene derived from crude oil. The polymer degrades completely in composting conditions within 18 months. A major Australian supermarket chain announces plans to switch all its plastic bags to this new material within five years.
Evaluate whether this new bio-based polymer solves all of polyethylene's environmental problems, or only some of them. Use evidence from polymer chemistry and the plastics lifecycle in your answer. Consider: raw materials, production, use, end-of-life (composting vs landfill vs ocean), and any trade-offs or remaining concerns.
1. DNA is a natural polymer. How is DNA's monomer–polymer relationship similar to, and different from, ethene's relationship to polyethylene? Use at least two chemical comparisons in your answer (for example, consider the type of monomer, how the monomers join, and the structure of the resulting chain).
2. UHMWPE (ultra-high-molecular-weight polyethylene) is made from the same ethene monomer as a supermarket plastic bag, yet it is used in bulletproof vests and cut-resistant gloves. Explain, using your knowledge of polymer chain length and chain entanglement, how the same monomer can produce materials with such dramatically different properties.
Wrap Up
In one sentence, what was the main idea of this lesson?