ADVANCED POLYMERS: INVESTIGATIONS ON THE INFLUENCE OF MOLECULAR DESIGN, STRUCTURAL PARAMETERS, INTERMOLECULAR FORCES AND PROCESS DESIGN ON PROPERTIES

摘要

Investigations based on modem methods of molecular level design philosophy for the design of "structure controlled macromolecules' and similar techniques, carried out on both natural and synthetic polymers involving synthetic and structural studies are presented. Simple chemical modifications such as introducing a phosphate group or a bromine atom on natural monomers based on cashewnut shell liquid (CNSL) and rubber teed oil (RSO) or a grafting reaction on natural polymers such as cellulose brought in enormous improvements in properties. Introducing an acrylate group into cardanol followed by emulsion polymerization changed the area of CNSL chemistry for better applications of these polymers in transparent resin for surface coatings. Further explorations on the special structural features of cardanol led to the finding that the phosphoric acid and sulphonic acid derivatives of cardanol possess multiple functions of plasticization, emulsification, protonation and solubilisation for the preparation of melt/solution processable conducting polyaniline. A judicious choice of comonomert which are characterized by the presence of an aliphatic carbon directly attached to the aromatic moiety enabled synthesis of thermotropic terpolyesters having transition temperatures as low as 240 deg C with a nematic phase required for easy processability. The extensive hydrogen bonding can alto generate LC phases by the alignment of the hydrogen bonded layer structures was shown in the case of poly(esteramide)s (PEA) prepared from amido diols (having a diamide link that can involve in extensive hydrogen bonding) whose aliphatic structures are not expected to contribute to LC phase formation. Similarly, certain azobenzene bated tide chain polymers having carboxylic acid groups were also found stabilised due to hydrogen bond formation. These LC polymers are expected to induce ease of processing and improved properties in thermoplastics and initial studies on rheology and processability are quite encouraging.