使用 \chemfig 定位聚合物支架

Question

我想创建一种这样的聚合物。

这是我目前得到的。

\documentclass{article}
\usepackage{chemfig}
\usepackage{mhchem}
\makeatletter
 \newcommand*\setpolymerdelim[2]{\def\polymer@delimleft{#1}\def\polymer@delimright{#2}}

 \newcommand*\makepolymerbraces[5]{%
  \edef\polymer@delimhalfdim{\the\dimexpr(#1+#2)/2}%
  \edef\polymer@delimvshift{\the\dimexpr(#1-#2)/2}%
  \chemmove{
    \node[at=(#4),yshift=(\polymer@delimvshift)]
      {$
       \left\polymer@delimleft
         \vrule height\polymer@delimhalfdim depth\polymer@delimhalfdim width0pt
       \right.
      $};
    \node[at=(#5),yshift=(\polymer@delimvshift)]
      {$
        \left.
          \vrule height\polymer@delimhalfdim depth\polymer@delimhalfdim width0pt
        \right\polymer@delimright_{\rlap{#3}}
      $};
  }%
}
\makeatother
\begin{document}
        \schemestart
        \setpolymerdelim[] 
        \chemfig{-[@{b1},0.4]-[,.8]Si(-[:90,.5,,,white]\ce{R})-[@{b3},0.2]-O-[@{b4},0.3][@{b2},0.6]}
        \makepolymerbraces{30pt}{30pt}{$n$}{b1}{b2}
        \setpolymerdelim()
        \makepolymerbraces{30pt}{30pt}{$1.5$}{b3}{b4}
        \schemestop
\end{document}

[@{b3},0.2]所以问题是：如何正确定位支架？用这四个点排列它们并在数千次之后更改数字@{bx},xx直到看起来不错并不是那么好 。

有没有更好的方法来构建这样的聚合物？

谢谢，弗朗兹

Answer 1

我会做这样的事情：

\documentclass{article}
\usepackage{chemfig}
\usepackage{chemmacros}
\chemsetup{
  modules = {polymers}
}
\begin{document}

\chemfig{-[@{a}]\chemabove{Si}{R}-[@{b,.75}]O-[@{c,.25}]-[@{d,.25},.5]}
\makepolymerdelims{10pt}{a}{d}
\makepolymerdelims[subscript=$\scriptstyle\!1.5$,delimiters=()]{10pt}{b}{c}

\end{document}

该示例使用包\makepolymerdelims中的定义，chemmacros但其思想与手册中建议的宏相同chemfig。