A new family of materials is said to allow production of new types of acrylic or styrenic block copolymers, as well as improved versions of existing copolymers with tighter control of molecular weight and sequencing of monomer units.

A new family of materials is said to allow production of new types of acrylic or styrenic block copolymers, as well as improved versions of existing copolymers with tighter control of molecular weight and sequencing of monomer units. New BlocBuilder technology from Arkema Inc.'s Organic Peroxides unit, Philadelphia, will be available in three forms: BlocBuilder nitroxide compounds-a reaction controller and free-radical initiator in one molecule-are available to resin producers for making block copolymers. Developmental FlexiBloc Living Polymers-reactive prepolymers made with BlocBuilder-are offered to compounders and resin producers for reactive extrusion and chain extension. Specialty block copolymers made with BlocBuilder are being developed by Arkema for sale to molders, extruders, and compounders. Developed by Arkema's French parent, BlocBuilder nitroxides are non-toxic, non-corrosive compounds that impart no odor or discoloration, unlike other radical polymerization controllers. And unlike most free-radical initiators, which tend to produce random copolymers, Arkema says nitroxides provide control of molecular weight and the size and placement of copolymer blocks. These blocks can assemble into domains of nanometer scale, which allow impact modification and other functionality while retaining transparency. Arkema uses BlocBuilder technology to make its new Nanostrength acrylic copolymer tougheners and compatibilizers (reported in January). BlocBuilder could also be used to enhance flow, paintability, scratch resistance, or adhesive properties. The latter could be used in tie-layer resins, TPEs for hard/soft overmolding, or for pretreating nanoclays or wood fibers. Arkema's first FlexiBloc prepolymer for reactive extrusion is a developmental butyl acrylate that can be used to build heat- and uv-stable toughening into the backbone of a block copolymer. It has reactive nitroxide end groups that are stable at room temperature and reactive only above a certain temperature-an attractive characteristic of nitroxides in general.

Arkema Inc
Organic Peroxides Div
Three Parkway Philadelphia, PA 19102
Phone (215) 419-7000 Fax (215) 419-7413