外文翻譯---20世紀(jì)到21世紀(jì)水性涂料面臨的技術(shù)挑戰(zhàn)英文版

1、where R is the reflectance of the sample, ? is the distance on the surface between two points, ? is the angular frequency, k is the wave number, f is the focal length of the incident radiation, and ? is the rms height of

2、 the surface. A 2D analysis of the optics has been carried out by Ogilvy (35). Whitehouse concluded (34) (for undulations with length scale greater than the wavelength of the incident radiation) that the surface appeared

3、 glossy if the probability density of the slopes on the surface was strictly confined to a narrow angle. Biocompatibility. Finally, biological interac- tions with a surface have also been found to depend on its topograph

4、y. A good review of the topological control of cell adhesion and activity on a surface has been made by Curtis and Wilkinson (36), and a more general review of the role of polymer biomaterials may also be found (37). Suc

5、h considerations are relevant for a number of in vivo and in vitro applications, such as biological sensors, hip replacements (38), and more complex tissue implants such as replacement bone, where the growth of cells wit

6、hin the artificial structure is to be encour- aged. For example, the size and morphology of crystals at the surface of octacalcium phos- phate–coated collagen have been shown to af- fect the interaction of cells with the

7、 surface, as illustrated in Fig. 4. The larger scale topography was found to lead to less favorable spheroidal cells that formed fewer intercellular connections (39). In some cases, the topography of a surface may be car

8、efully controlled to promote cell adhesion (40, 41).ConclusionThe topography of a surface is a direct result of the nature of the material that defines it.The analysis of the topography of a sample, made possible on the

9、nanoscale by the devel- opment of AFM techniques, needs to be care- fully considered in order to relate the com- plexity of a 2D surface to the material’s properties. The result will be the better con- trol of a number o

10、f properties, such as optical finish, and of the interaction of a surface with a secondary material, whether that be an ad- hesive, a secondary component of a compos- ite, or a biological species.References and Notes 1.

11、J. D. Affinito et al., Thin Solid Films 291, 63 (1996). 2. J. A. DeAro, K. D. Weston, S. K. Buratto, U. Lemmer, Chem. Phys. Lett. 277, 532 (1997). 3. Y. Nabetani, M. Yamasaki, A. Miura, N. Tamai, Thin Solid Films 393, 32

12、9 (2001). 4. M. Sferrazza et al., Phys. Rev. Lett. 78, 3693 (1997). 5. E. Scha ¨ffer, T. Thurn-Albrecht, T. P. Russell, U. Steiner, Europhys. Lett. 53, 218 (2001). 6. D. G. Bucknall, G. A. D. Briggs, MRS Symp. Ser.:

13、 Nanopatterning: Ultralarge-Scale Integration Bio- technol. 705, 151 (2002), L. Merhari, K. E. Gonsalves, E. A. Dobisz, M. Angelopulss, D. Herr, Eds. 7. S. Walheim, E. Scha ¨ffer, J. Mlynek, U. Steiner, Science 283,

14、 520 (1999). 8. J. Heier, E. Sivaniah, E. J. Kramer, Macromolecules 32, 9007 (1999). 9. T. Thurn-Albrecht, J. DeRouchey, T. P. Russell, Mac- romolecules 33, 3250 (2000). 10. A. Karim et al., Macromolecules 31, 857 (1998)

15、. 11. X. P. Jiang, H. P. Zheng, S. Gourdin, P. T. Hammond, Langmuir 18, 2607 (2002). 12. G. Goldbeck-Wood et al., Macromolecules 35, 5283 (2002). 13. V. N. Bliznyuk, K. Kirov, H. E. Assender, G. A. D. Briggs, Polym. Prep

16、rints 41, 1489 (2000). 14. F. Dinelli, H. E. Assender, K. Kirov, O. V. Kolosov, Polymer 41, 4285 (2000). 15. C. Rauwendaal, Polymer Extrusion (Hanser, Munich, 1985). 16. S.-J. Liu, Plast. Rubber Composites 30, 170 (2001)

17、. 17. B. Monasse et al., Plast. Elastomeres Mag. 53, 29 (2001). 18. Y. Oyanagi, Int. Polym. Sci. Technol. 24, T38 (1997). 19. A. Guinier, X-ray Diffraction in Crystals, ImperfectCrystals, and Amorphous Bodies ( W. H. Fre

18、eman, San Francisco, 1963). 20. V. N. Bliznyuk, V. M. Burlakov, H. E. Assender, G. A. D. Briggs, Y. Tsukahara, Macromol. Symp. 167, 89 (2001). 21. W. M. Tong, R. S. Williams, Annu. Rev. Phys. Chem. 45, 401 (1994). 22. P.

19、 Meakin, Fractals, Scaling and Growth Far from Equilibrium (Cambridge Univ. Press, Cambridge, 1998). 23. C. M. Chan, T. M. Ko, H. Hiraoka, Surf. Sci. Rep. 24, 3 (1996). 24. E. M. Liston, L. Martinu, M. R. Wertheimer, J.

20、Adhesion Sci. Technol. 7, 1091 (1993). 25. Q. C. Sun, D. D. Zhang, L. C. Wadsworth, Tappi J. 81, 177 (1998). 26. V. Bliznyuk et al., Macromolecules 32, 361 (1999). 27. N. Zettsu, T. Ubukata, T. Seki, K. Ichimura, Adv. Ma

21、ter. 13, 1693 (2001). 28. R. S. Hunter, R. W. Harold, The Measurement of Appearance (Wiley, New York, ed. 2, 1987). 29. H. Davies, Proc. Inst. Electr. Eng. 101, 209 (1954). 30. F. M. Willmouth, in Optical Properties of P

22、olymers, G. H. Meeten, Ed. (Elsevier, Amsterdam, 1986). 31. D. Porter, Group Interaction Modelling of Polymer Properties (Marcel Dekker, New York, 1995). 32. P. Beckmann, A. Spizzichino, The Scattering of Elec- tromagnet

23、ic Waves from Rough Surfaces (Pergamon, New York, 1987). 33. K. Porfyrakis, N. Marston, H. E. Assender, in preparation. 34. D. J. Whitehouse, Proc. Inst. Mech. Eng. B: J. Eng. Manuf. 207, 31 (1993). 35. J. A. Ogilvy, The

24、ory of Wave Scattering from Random Rough Surfaces (Adam Hilger, Bristol, UK, 1991). 36. A. Curtis, C. Wilkinson, Biomaterials 18, 1573 (1997). 37. L. G. Griffith, Acta Mater. 48, 263 (2000). 38. T. M. McGloughlin, A. G.

25、Kavanagh, Proc. Inst. Mech. Eng. Part H–J. Eng. Med. 214, 349 (2000). 39. A. C. Lawson et al., MRS Symp. Ser.: Biomed. Mater.: Drug Delivery, Implants Tissue Eng. 550, 235 (1999), T. Neenan, M. Marcolongo, R. F. Valentin

26、i, Eds. 40. C. S. Ranucci, P. V. Moghe, J. Biomed. Mater. Res. 54, 149 (2001). 41. P. Banerjee, D. J. Irvine, A. M. Mayes, L. G. Griffith, J. Biomed. Mater. Res. 50, 331 (2000). 42. The authors acknowledge contributions

27、to this work from A. Briggs, D. Bucknall, V. Burlakov, J. Czernuska, and S. Wilkinson from Oxford University; N. Marston and I. Robinson from Lucite International; and Y. Tsukahara from the Toppan Printing Company.V I E

28、W P O I N T20th- to 21st-Century Technological Challenges in Soft CoatingsRobert R. Matheson Jr.Coatings are among the most ancient technologies of humankind. Rela- tively soft coatings comprising organic materials such

29、as blood, eggs, and extracts from plants were in use more than 20,000 years ago, and coating activity has been continuously practiced since then with gradually improv- ing materials and application techniques. The fundam

30、ental purposes of protecting and/or decorating substrates have remained ubiquitous across all the centuries and cultures of civilization. This article attempts to extrapolate the long tale of change in soft coating techn

31、ology from its current state by identifying some key problems that attract research and development efforts as our 21st century begins.Humans have been decorating and protecting various surfaces for many thousands of yea

32、rs. One very useful way of accomplishing either or both of those tasks is to apply a thin layer of some new material with appropriate char-acteristics (of appearance, durability, adhe- sion, and application requirements)

33、 directly onto the surface of interest. That new material is a coating. Understandably, the early history of coatings is a story of very specialized,often unique material combinations, as trial and error achieved goals w

34、ith only the mate- rials at hand in nature. This heritage of cus- tomization is still detectable in the modern coatings world, which demands a tremendous amount from the materials—often synthetic but some still containin

35、g or made of natural products—to be thinly applied on a surface. They need to be easily and uniformly applied; set up within a reasonable amount of time and process constraints; have a minimal environ- mental impact in t

36、heir synthesis, combina-DuPont Performance Coatings, 950 Stephenson High- way, Troy, MI 48083, USA. E-mail: robert.r.matheson@ usa.dupont.com9 AUGUST 2002 VOL 297 SCIENCE www.sciencemag.org 976M A T E R I A L S S C I E N

37、 C E : S O F T S U R F A C E Son March 23, 2010 www.sciencemag.org Downloaded from to take great care in synthesizing the var- nish ingredients so that no especially trou- blesome reactions can ever occur. Some side rea

38、ctions are understandably more del- eterious than others, and the goal is to leave no opportunity for the most troublesome, no matter what conditions might appear. This leads to the use of controlled polymer- ization tec

39、hniques [exemplified but certain- ly not limited to group transfer polymeriza- tion (7) for acrylic materials], rigorous exclusion of nonfunctional (unable to par- ticipate in curing) matrix materials, and optimizing mol

40、ar mass distributions to avoid untimely immiscibility during cure and similar strategies. The specific field of automotive coating has been in the fore- front of this activity because of the ex- tremely high performance

41、standards and powerful economic incentives found in mass-producing automobiles. Some of the new synthetic and analytical techniques be- ing introduced for controlling and monitor- ing automotive enamels have been de- scr

42、ibed (8). Decorative coatings in particular need to incorporate pigments, dyes, reflective metal, and mica flakes for many applications. One common technique for effectively distribut- ing such particles is to cover thei

43、r surfaces with dispersants that aid in their dispersion in the bulk of the coating and prevent reagglom- eration under the variety of circumstances that might arise later. Exquisite control of the molecular structure is

44、 needed in order to achieve good distribution of the particles, minimal mobility once applied to a surface, the ability to resist forces that drive re- agglomeration, and compatibility with the bulk coating and yet not i

45、nduce problems with adhesion, application, or long-term per- formance. Because pigments are very fre- quently the most expensive ingredients in a decorative coating, it is important to use them efficiently. Additionally,

46、 as solvent concen- tration and variety are decreased because of the environmental pressures previously cited, opportunities for managing dispersion prob- lems by modifying the coating medium (the coating vehicle) decrea

47、se. Small wonder that the chemistry used to make modern dispers- ants provides an exceptionally clear picture of the state of the art in molecular control in coatings. Techniques for making block co- polymers (each block

48、 designed for affinity to either a surface or the solvent environment) have been developed and commercialized and are still being improved. The patent art is extensive and growing, but that from C. Ho- sotte-Filbert (9)

49、is a representative example.Functional CoatingsA fourth modern frontier in the world of soft coatings can be descriptively called “postcure reactivity” for varnishes, or perhaps “in-usereactivity” for lacquers. Such reac

50、tions have been recognized for a long time in examples such as the long-term oxidation of alkyd var- nishes and many lacquers based on natural products. Historically, these have been viewed as troublesome instabilities.

51、Howev- er, it has been learned that some instances of postcure chemistry have advantages, with one example being the slow condensation and interchange of siloxane bonds in organosilane enamels (10). These can act to rela

52、x stresses that otherwise grow uncompensated in light- and oxidation-stressed exterior coatings. Het- erogeneous coatings that react to cracks or fractures by releasing postcure repair ingre- dients have been postulated

53、(11). Even more sophisticated uses in con- trolled release or other transport control prob- lems can be sketched today. It should be noted that a great many instances exist in which coatings are used to manipulate (gen-

54、erally to retard, delay, or prevent) the trans- port and exchange of materials. Atmospheric oxygen contacting food, carbon dioxide exit- ing carbonated beverages, the release of pharmaceuticals into the body, electrical

55、charge leaking into a device component, heat exiting an isothermal environment, or water and ionic materials contacting corro- sion-susceptible metals are examples where the transport characteristics of coatings are impo

56、rtant in determining performance. The long-term capability of a coating to im- prove or at the least react to compensate for a declining transport characteristic may be just as useful as the same ability to offset declin

57、ing mechanical characteristics.Industrial Scale ChallengesA final class of problems driving innovation in modern coatings can be found in the costs and limitations of the heating step in enamel processing. Not surprising

58、ly, these problems include the capital and energy costs associat- ed with heating objects with large thermal masses, damage to heat-sensitive substrates, and the inventory problems that accumulate with long cycle times i

59、n any process. The most direct approach is to reduce the required baking temperature and/or time. There is scope here for novel chemical reactions and catalyst innovations, both of which command attention today. Alternat

60、ively, if the curing reactions can be activated by a mechanism other than simple heating, then problems can be minimized without losing the cure-in- duced improvements in coating performance. Much current work is directe

61、d to radiation- curable (with ultraviolet light, electron beams, and even visible light) coatings and efforts to extend their current embodiments to complex articles and long-term use (12). Powder coatings and liquid coa

62、tings are both objects of study and innovation. The major challenge faced in such development arisesfrom limitations on the uniformity of cure for incompletely transparent coatings (shadowed areas do not receive the same

63、 flux of radia- tion) or coatings on complex shapes. Examples of specific new products arising in response to one or another of these five general development areas can be found in many places and from many development l

64、ab- oratories. Perhaps no example exists that illus- trates all, but there is at least one that comes close. A need exists in the automotive world for a painting system with lower environmental emissions (particularly VO

65、Cs), improved resis- tance to environmental damage (particularly mechanical scratching), outdoor durability ap- proaching a decade, corrosion resistance of the coated metal for the same period of time, and improved appli

66、cation robustness. This need has been recently met with what might be consid- ered an exemplary modern coating system. Four layers of coating are used: First, an anti- corrosion coating (now free of heavy metals) is appl

67、ied by cathodic electrodeposition; second, a powder primer (now with zero VOCs); third, a waterborne layer containing pigments (now with minimal VOCs and minimal HAPs with modern polymeric dispersant molecules); and fina

68、lly, a new clearcoat (now with more than 20% lower VOCs, greatly improved scratch resistance, and excellent resistance to acid rain, chemical attack, and photochemical exposure). All this is applied with the use of exist