Posted by Golf balls may look simple, but they are highly engineered products. Their performance depends on carefully designed combinations of cores, covers, polymers and surface technologies, all developed to improve distance, spin, feel and durability. In this rapidly changing field, one particularly fascinating innovation involves a rather unexpected ingredient: cyclodextrin engineered as a building block of supramolecular polymers: polyrotaxanes.
In a polyrotaxane, cyclodextrin rings are threaded onto a linear polymer chain and prevented from sliding off by bulky end groups. The rings can nevertheless move along the polymer chain, giving the material unusual dynamic and mechanical properties. This molecular-level mobility can help redistribute mechanical stress within a polymer network, which is also referred as a “slide-ring gel”.
This elegant chemistry found an unexpected application in golf-ball technology. Sumitomo Rubber Industries, Ltd. filed a patent application for a golf-ball formulation [1] incorporated cyclodextrin-based polyrotaxanes into polyurethane cover materials, with the aim of improving properties such as spin, feel, resilience and durability. Particularly interesting was the potential to improve spin performance under wet conditions — an important advantage for shots around the green.
What makes this innovation especially remarkable is that the technology did not remain a laboratory curiosity. The technology subsequently became associated with the development of high-performance golf balls, including the Srixon Z-STAR family in March 2019 with structure as illustrated in the figure below:
source: https://www.mygolfway.com/
There is something particularly remarkable about this example of innovation. Sporting equipment is a notoriously fast-moving technology sector: new generations of golf balls, tennis rackets, bicycles and other equipment appear continuously, with manufacturers constantly replacing materials and designs in pursuit of incremental performance improvements. Yet a cyclodextrin-based technology introduced years ago can still be found in a commercially available golf-ball product today.
This is an important reminder that innovation is not always about replacing yesterday’s technology with something newer. Sometimes, a genuinely clever molecular concept proves sufficiently effective to survive several generations of product development.
The golf-ball story also illustrates the extraordinary versatility of cyclodextrins. The same family of molecules that is widely used in pharmaceuticals, cosmetics and food can become part of a sophisticated mechanically interlocked polymer and ultimately contribute to the performance of a product travelling more than 200 kilometres per hour after being struck by a golf club.
From molecular containers to molecular pulleys, cyclodextrins continue to demonstrate that their potential extends far beyond their traditional applications. And perhaps one of the most surprising places to see this innovation in action is right on the golf course.
[1] Sumitomo Rubber Industries, Ltd.: US patent application 20210275875