ABSTRACT
Nowadays, the interest in the degradable polymer gels and networks has significantly grown. The patent literature shows that IPNs were invented over and over again, beginning in 1914. Alysworth invented the first IPN combining the new phenol-formaldehyde compositions with natural rubber and sulfur [1-3] and made the world’s first rubber-toughened plastic, decades before rubber-toughened synthetics were commercial.
