Bi-Monthly Newsletter


PEL PLASTICS UPDATE highlights recent progress in key areas of polymer/plastics technology including: catalysis, biopolymers, smart/functional polymers, alloys & blends, nanotechnology, polymer modification and new ventures. A recent issue of PEL Plastics Update follows.


Vol. 8, No. 2
PEL PLASTICS UPDATE
January - February, 2002
By Mort Wallach
ISSN 1094-656X

RECENT PROGRESS IN POLYMER/PLASTICS TECHNOLOGY
TECHNOLOGY & APPLICATIONS

COMPLIMENTARY COPY

Nanotechnology - New polymer nanowires were obtained on silicon wafer surfaces via AFM dip-pen techniques written as EDOT monomer nanolines which are then electro- chemically polymerized. This could lead to the fabrication of polymer nanodevices for use in electronics, defense, pharmaceutical, or biotechnology applications. Also, well defined nanoparticles of Pd and CdS were synthesized and stabilized via terpyridine ligands and functionalized by polyethylene glycol in a 5 nm shell. Such nanoparticles have potential in catalysis, optical and electronic devices.

  • Profs. J. Liu and M. Grinstaff at Duke U. have developed a nanolithographic technique for patterning conductive polymer nanowires on semiconductor surfaces. They used a direct-writing method to prepare well defined polythiophene lines less than 100 nm in crossection on oxidized silicon wafer surfaces. The polymer lines are prepared by coating an atomic force microscope tip with 3,4-ethylene-dioxythiophene (EDOT) and then translating the tip across the wafer. The monomer is electrochem- ically polymerized at the interface by applying a voltage between the tip and the silicon wafer. The nanowire morphology is controlled by varying the humidity, applied voltage, and the speed of tip translation. The capability of nanoscale direct-write to pattern polymeric materials with useful electronic and electro-optical properties should create various opportunities since many monomers and polymers are available which are amenable to this method. A number of techniques have significant limitations for patterning conductive polymers in the sub-100 nm range where this method could be effective. These include: photolithography, micro-contact printing, template synthesis, and scanning electrochemical microlithography.(J. Am. Chem. Soc., Dec. 19, 2001).
  • Prof. U. Schubert and coworkers at Eindhoven Univ. of Technology, The Netherlands, synthesized Pd and CdS nanoparticles using terpyridine ligands which stabilize the particles and provide a route to functionalization. Various possible reacting telechellic polymers open up a new route toward the production of functional nanoclusters. In this work functionalization to terpyridine ligands is achieved with polyethylene glycol (PEG) resulting in a 5 nm shell over CdS. Future work will focus on different metals and other polymers with various functional groups and on controlling structure and morphology by self-assembly of bipyridine and terpyridine. Potential applications involve catalysis, optical and electronic devices. (PMSE, 85, 508, 2001)

Smart/Functional Polymers - Sensor systems were developed for vapor detection consisting of arrays of polymer composite film chemiresistors. These films contain conductive carbon black particles dispersed in insulating organic polymers or blends and can detect a variety of vapor systems with good sensitivity and accuracy.

  • Prof. N. Lewis and coworkers at Cal. Tech. have developed these detector arrays fabricated from conducting polymer composite films which provide a convenient, flexible technique for vapor detection. The individual sensor elements are constructed from films consisting of carbon black particles dispersed in insulating organic polymers. The carbon black imparts electrical conductivity to the film whereas the different organic polymers are the source of chemical diversity between elements in the sensor array. Swelling of the polymer upon exposure to a vapor increases the resistance of the film thereby providing a simple means for monitoring the presence of the vapor. Different polymer compositions are present on each sensor element so an array of elements responds to a wide variety of vapors (or mixtures of vapors) in a distinctive and identifiable manor. Improved diversity in the detector array can be obtained through a wide choice of polymers, polymer blends, carbon blacks, and plasticizers. The electrical resistance signal output from the array can be readily integrated into software-based or hardware-based neural network processors allowing for an integration of sensing and analysis functions into a compact low power system. Such arrays present an interesting opportunity for implementing pattern-recognition based approaches to vapor detection and using combinatorial chemistry methodologies in polymer fabrication and sensor preparation.(Polymer Preprints, 42(2) 653, 2001)

Catalysis/Applications - Metallocene based cyclic olefin copolymers of varied Tg were developed which can be tailored to a variety of applications, from medical packaging, food packaging, and disc drive components to flat-panel display substrates.

  • Union Chemical Labs of Taiwan’s Industrial Technology Research Institute has developed these metallocene based cyclic olefin copolymers (COC) by altering the norbornene content to yield glass transition temperatures from 70 to 300C. Cyclic olefin copolymers can compete with polycarbonate (PC) in DVD-R rewritable digital video disks for data storage applications (15G) where relative to PC, COC would not absorb the required blue light, have lower birefringence and better heat resistance. Also, high Tg COC could allow manufacture of an all-plastic thin-film transistor liquid crystal display (LCD) eliminating the use of heavy and fragile glass display substrates. These copolymers can allow half the display thickness, with weight reductions of over 60%, and 10X greater impact strength. Since the displays are typically made using metal deposition processes at up to 300C suitable plastics must have a Tg of at least 250C. Also, at the required molding process temperature (~370C) polyolefin stability could be impaired and additional heat stabilization may be required. Overall, with a variable Tg over a wide temperature range this COC family has potential in a variety of applications from medical and food packaging, disk-drive components, and possibly flat-panel-display-substrates. Other new COC applications include Ticona’s Topas COC/polyolefin blend for sealant barrier film and Zeon’s COC, sheet for front-light LCD panels. (Modern Plastics, Feb. 2002, p 36)

Alloys & Blends - Reactive extrusion through ultrasonic systems installed in the extruder barrel or die was effective in producing PP/EPDM blends without a compatibilizer. This technique was also able to break enough rubber crosslinks rendering such cured material flowable again.

  • Prof. A. Isayev of U. of Akron at the recent K-Plast in Dusseldorf showed how an immiscible blend of plastic and rubber can attain stable mixtures in conventional twin screw extruders using high powered ultrasonic vibrations. The technique can substitute for chemical compatibilizing agents. The ultrasonic device is placed in either the extruder barrel or in the die. It is proposed that the high frequency vibrations can break up chemical bonds and cause new ones to form. Rubber molecules at the edges of elastomer domains within the PP matrix are thought to copolymerize with the matrix making the domains stable and prevent demixing and reagglomeration. The method was demonstrated with PP/EPDM wherein electron micrographs show much smaller domains after ultrasonic treatment. The method could be useful in HIPS preparation. (Plastics Technology, November, 2001, p 23)

Selected Patents - Among 1000 patents reviewed during this period, there are several noteworthy inventions involving: blends of PVDF and aromatic polyimide, aromatic polycarbodiimides, electrochemical sensors from conductive composites, and nanoscopic acrylamide polymer magnetic microspheres.

  • "Compatible Blends Of Polyvinylidene Fluoride And Aromatic Polyimide". E. Pearce et al (Ausimont USA, Inc.) US 6,313,222, Nov. 6, 2001. A miscible polymer blend of superior mechanical strength, hardness and abrasion or mar resistance comprises PVDF and at least one compatible aromatic polyimide. The aromatic polyimide in the miscible polymer blend acts as a nucleating agent for PVDF crystallization. The miscible polymer blend comprising PVDF and aromatic polyimide does not exhibit the negative characteristic of reduced mechanical strength encountered in PVDF and polymer alloys known in the art. The PVDF/aromatic polyimide alloy is prepared by dissolving, separately, PVDF and the aromatic polyimide in a solvent and blending the solutions to form the required composition. (Chem. Abs. 135: 345253n)
  • "Preparation Of Aromatic Polycarbodiimides and Fims Thereof". M. Sakamoto et. al. (Nitto Denko Corp.) US 6,313,258, Nov. 6, 2001. An aromatic polycarbodi- imide having a (RN:C:N) structural unit, wherein R = aromatic group optionally containing fluorine or oxygen, is disclosed. The aromatic polycarbodiimide can give films, moldings, adhesives and the like each having excellent characteristic such as heat resistance, high dimensional stability, high moisture resistance or the like, and therefore is suitable for use as a heat resistant covering material in, for example, production of electronic parts. 2,2Bis[4-(4-isocyanatophenoxy)phenyl]hexafluoro- propane was polymerized and cast into a film.(Chem. Abs. 135: 358372a)
  • "Electrochemical Sensors Made From Conductive Polymer Composite Materials and Methods of Making Same". S. Foulger (Pirelli Cables and Systems LLC) US 6,315,956, Nov. 13, 2001. An electrochemical sensor which is tailored for sensitivity to specific chemical analytes by selecting proper constituents. The electrochemical sensor is comprised of an immiscible polymer blend of at least two polymers in which a conductive filler is dispersed in one of the polymers of the blend through a multiple percolation approach to compounding. When in the presence of a chemical analyte which is in either a liquid or vapor phase, one phase of the dual immiscible polymer blend swells, effecting a decrease in the conductivity, or increase in resistivity, of the polymer blend. The electrochemical sensor is reversible in that when the chemical analyte evaporates or is removed, the polymer blend returns to its original condition. With the multiple percolation approach it is possible to make a single composite material identifiably sensitive to various chemical analytes by incorporating several major phase materials into the immiscible polymer blend, each having an affinity for swelling for a different analyte. Further, the multiple percolation approach allows sensors to be made at extremely low cost. (Chem. Abs. 135: 366147w)
  • "Preparation Of Amino-Containing Acrylamide Polymer Magnetic Microspheres Containing Magnetic Fluid Cores". M. Zhang et. al. (Harbin Engineering Univ., Peoples Republic of China) Faming Zhuanli Shenqing Gongkai Shuomingshu CN 1,290,721, Apr. 11, 2001. The method for preparing magnetic microspheres comprises preparing magnetic fluids (such as Fe3O4 or Co-Fe3O4) with particle size 10 nm by chemically coprecipitating absorbing initiator (such as potassium persulfate) on the surface of the magnetic fluid particles by ultrasonic dispersing and mechanical stirring to form initiating point of polymerization, dispersing hydrophilic monomers [such as acrylamide, allylamine and N,N’-methylenebis(acrylamide)] in the magnetic fluid, and solution polymerizing to form magnetic microsphere containing magnetic fluid cores and amino-containing polyacrylamide shell. The aminopolyacrylamide magnetic microspheres are useful as carriers of enzymes, antibodies, and targeting drugs. (Chem. Abs. 135: 358825a)

 

forms tailored elastomers via reactive extrusion. Examples include a family of polyester-ether block copolymers containing hard PBT and soft polyether-glycol segments.

  • The process combines a Cyclics Corporation liquid low molecular weight PBT cyclic oligomer with other polymers. This approach allows fast and easy production of a wide range of hard and soft copolyester-ether block copolymers directly in the extruder. It opens up the possibility of creating elastomeric materials with new property profiles and to tailor them to customer specifications by simply adjusting the ratio of inputs before extrusion. These polyester-ether elastomer block copolymers contain alternating hard PBT and soft polyether glycol segments. Competitive elastomer brands include DuPont Hytrel, and DSM Arnitel. (Plastics Technology, February 2002, p. 29)

Fuel Cells - Several new sulfonated polymers and copolymers were synthesized as possible replacements for Nafion membranes in PEM fuel cells. These typically contain high performance polymer backbones aimed at overcoming the moisture loss (above 80C) and possibly cost and other issues associated with current membranes. Actual tests in fuel cells are underway.

  • Prof. J. McGrath and coworkers at Virginia Polytechnic Inst. in a series of recent papers have introduced the following candidates in an impressive synthetic condensa- tion polymer chemistry demonstration: "Polyarylene Ether Block Copolymers Containing Sulfonate Groups" (PMSE, 85, 517, 2001), "Heteropolyacid/Sulfonated Poly(Arylene Ether Sulfone) Composites For Proton Exchange Membrane Fuel Cells" (PMSE, 85, 520, 2001), "Sulfonated Poly(Arylene Ether-b-Polyimide) Segmented Copolymers" (PMSE, 84, 105, 2001), "Preparation And Properties Of Sulfonated Or Phosphinated Polybenzimidazoles and Polybenzoxazoles" (PMSE, 84, 899, 2001), "Sulfonated Six Membered Ring Polyimides As Proton Exchange Membranes: Synthesis And Characterization" (PMSE, 84, 911, 2001), and "Synthesis Of Sulfonated Poly(Arylene Ether Phosphene Oxide Sulfone) Via Direct Polymeriza- tion" (PMSE, 84, 913, 2001). Basic polymer tests are generally encouraging and fuel cell membrane evaluations are underway.

New Polymer Ventures - Solvay will become a major producer of fluoropolymers by purchasing Ausimont’s fluorinated specialties business, and GE is acquiring LNP Engineering Plastics from Kawasaki Steel Corp. to establish a worldwide compounding operation.

  • Solvay S. A. of Brussels, Belgium will buy Ausimont, the Italian based fluorinated specialties group, from Montedison of Italy for 1.3 billion euros subject to regulatory approval. This would essentially double it’s fluorinated specialties business and make Solvay-the number-two producer of fluoropolymers worldwide. The deal marks Solvay’s continuing shift away from commodity polymers. Ausimont currently produces Hylar PVDF, Algoflon PTFE, Hyflon MFA and PFA, Halar ECTFE, and Tecnoflon fluoroelastomers, while Solvay currently produces only Solef PVDF resins. The acquisition is expected to be completed by mid-year. (C&EN, Dec. 3, 2001, p. 14)
  • GE Plastics will acquire LNP Engineering Plastics from Kawasaki Steel Corp. The deal is expected to be completed in the first quarter. LNP operations will be combined with complementary GE units to form a global compounding business headquartered in Exton, PA which is LNP’s present headquarters. The merged compounding business will use the LNP name and will have 13 manufacturing locations (10 LNP and 3 GE) throughout the world. The GE plants focus on amorphous materials while the LNP sites focus on crystalline materials. (Modern Plastics, Feb. 2002, p. 16)

Dr. Mort Wallach has over twenty-five years experience in the plastics industry beginning at DuPont's Experimental Station, and ranging from resin, film, and plastic manufacture, to consumer products, transportation and aerospace. His contributions include twenty-four publications, four recent books, numerous patents, and key roles in commercial developments, such as Kapton polyimide film, high performance composites, novel consumer products, and engineered materials.

Presently, he is President of PEL Associates, a successful product development and consulting firm in polymer/plastics science and technology. He is a member of ACS, SPE, IUPAC, and Sigma Xi. Dr. Wallach is affiliated with: Teltech Network of Experts, The CT Technology Council, Conn/Step, The Fulbright Association, and The Licensing Executives Society.


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PEL PLASTICS UPDATE highlights recent progress in key areas of polymer/plasticstechnology and applications including: catalysis, biopolymers, smart/functional polymers, alloys & blends, nanotechnology, polymer modification and new ventures. These citations are selected from a review of over 1000 articles in 100 journals, over 1000 US and foreign patents, and key conferences worldwide.

 

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