Silicone replica method

More elaborate decorative effects may be obtained by taking from a hand-tooled or stitched master product a liquid silicon replica, the cured silicon matrix being used in conjunction with the electrode to reproduce the original finish on vinyl. (This method of embossment is suitable for products such as belts, footwear, handbags, luggage, and cases for stationery.)... 

Baneqee HD, Sen S, Acharya HN, (1982) Investigations on the production of silicon from rice husks by the magnesium method. Mater Sci Eng 52 173-179 Bao Z, Weatherspoon MR, Shian S, Cai Y, Graham PD, Allan SM, Ahmad G, Dickerson MB, Church BC, Kang Z, Abernathy HW III, Summers CJ, Liu M, Sandhage KH (2007) Chemical reduction of three-dimensional silica micro-assemblies into microporous silicon replicas. Nature 446 172-175... 

Lambrechts et al. [35] described a method where silicone impressions of molar and premolar teeth were taken at 6-monthly intervals over a period of 48 months, in a study involving 21 subjects. The impressions were taken of teeth with established occlusal attrition and three reference points were ground into the enamel to form a common reference plane for measurements. The enamel wear was calculated by scanning positive replicas of the silicone impressions, using the reference points to calculate vertical wear. The authors found that the average vertical enamel wear over 4 years was 153 xm for molars and 83 pm for premolars. They also found that the wear rate showed a decreasing trend in each 6-month time period. 

Brittain et al. describe a series of soft lithographic methods that may be suited to the patterning of organic layers [82]. A pattern-transfer element is formed by pouring a liquid polymer, such as poly(dimethylsiloxane), onto a master made from silicon. The polymer is allowed to cure to form an elastomer, which can then be removed from the master. This replica can be used subsequently as a stamp to transfer chemical ink, such as a solution of an alkanethiol, to a surface. Features with dimensions of 40-100 nm can be produced with the technique of near-field, phase-shift photolithography [82]. 

A solvent-free method was introduced by chemical vapor deposition (CVD) of isoprene in a nitrogen atmosphere at 800 °C. This method yielded, after dissolution of the templating silica colloids, a conducting inverse carbon opal [77]. A semiconductor replica made of silicon could also be produced by CVD [78]. 

Very bulky samples may be dipped in or sprayed with a metal coating. Another preparative method is to mold the sample surface, eg, in silicone rubber, and to make a replica. However, there is a possibility of artifact formation... 

An SEM image of such a fiber replica is shown in Fig. 4.22. The rough fiber surface texture is associated with the finish. Gordon [295] reviewed the artifacts associated with silicone elastomer surface replicas, especially bubbling, and suggests that these methods must be used with great care. 

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