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In this study, a simple photocuring method is proposed for preparing PDMS elastomers using a homogenous poly(dimethylsiloxane) (PDMS) solution in tert‐butyl acrylate (tBA) as an alternative way of mechanically blending two kinds of PDMS respectively containing vinyl and hydridosilyl groups over a platinum catalyst. Poly(dimethylsiloxane‐co‐methylvinylsiloxane) (PDMSc) with 30 mol% of vinyl moieties is synthesized. The functionalized PDMS is estimated to be soluble in tBA from theoretical calculations of solubility parameters of PDMS and several liquid monomers. The PDMS solution is satisfactorily photocured under a conventional photoinitiator. Initial modulus and strain of the photocured films increase from 144 to 552 MPa and decrease from 3.96 to 1.84, respectively, as the tBA content rises from 5 to 30 wt%. They are extremely transparent in a visible region (T > 94%) regardless of the amount of tBA. The unreacted vinyl groups in PDMSc are inter‐ or intrareacted near 200 °C and γ‐hydrogen transfer reactions from the tert‐butyl groups in poly(tert‐butyl acrylate) occur over 250 °C. One of the photocrosslinked films exhibits outstanding performance as an electroactive polymer in application. In essence, this study will initiate a new methodological research into provision of PDMS elastomers using an easily formulated photocrosslinkable PDMS solution. [ABSTRACT FROM AUTHOR]

While evidence of polycentric urban form is extensive, questions remain regarding the value of agglomeration economies in an information economy, and hence whether polycentricity will persist over time. This paper examines employment spatial structure in four U.S. metropolitan areas between 1990 and 2009. We describe the spatial distribution of employment among centers and non‐center locations across time, examine the persistence of center boundaries, and test for monocentric and polycentric form via density gradient estimations. Results show that the four areas are all polycentric but of different degree. Despite some small fluctuations, metropolitan spatial structure is persistent even in the face of economic shocks in the 2000s: employment centers have not lost their importance and influence in the metro‐wide employment distribution over time. [ABSTRACT FROM AUTHOR]