Precision integral articles
This disclosure describes a processing approach for the rapid and efficient in-situ polymerization of specially prepared precursor mixtures to achieve near-net-shape production of objects/articles with exact dimensions. The process relies on the use of polymerizable compositions comprised of a mixture of a reactive plasticizer and an initiator, optionally also including a dead polymer, which compositions are semi-solid-like and induce little shrinkage upon curing as a result of their partially polymerized nature prior to processing. The articles of the invention have a surface and an interior core, the composition of the surface material being distinct from the composition of the core material while at the same time the surface and the core are an integral, monolithic entity. In addition, the articles are dimensionally stable and exhibit high fidelity replication.
1. A polymer article comprising a surface and a core, said core comprising a semi-interpenetrating crosslinked polymer network of reactive plasticizer and a dead polymer entangled with said reactive plasticizer, with a photochromic dye having been added to said surface and having partially penetrated into said core to render said surface and the center of said core of distinct compositions.
2. The polymer article of claim 1 wherein said reactive plasticizer is further crosslinked to the dead polymer.
3. The polymer article of claim 1 wherein the reactive plasticizer comprises less than 50% by weight of the composition of the article.
4. The polymer article of claim 1 wherein the reactive plasticizer comprises less than 25% by weight of the composition of the article.
5. The polymer article of claim 1 wherein the dead polymer is member selected from the group consisting of a thermoplastic elastomer, a high performance engineering thermoplastic, and a polycarbonate.
6. The polymer article of claim 1 , wherein the surface is biocompatible.
7. An article comprising a surface and an interior core, the article prepared by:
mixing together components comprising a dead polymer, a reactive plasticizer, and an initiator to form a semi-solid polymerizable core composition;
exposing the core composition to a photochromic dye and allowing penetration and diffusion of said photochromic dye into the core composition to form a semi-solid gradient composite material; and
exposing the gradient composite material to a source of polymerizing energy to give the article, wherein said core material comprises a semi-interpenetrating crosslinked polymer network of reactive plasticizer and a dead polymer entangled with said reactive plasticizer, and wherein the composition at the surface of the resultant article is distinct from the composition at the center of the interior core.
8. The polymer article of claim 7 wherein said components further comprise a stabilizer.