[Tex/LaTex] How to change font size for abstract title

Question

I've included milticol environment to my .tex file to use one column abstract in my article written using \documentclass[10pt, twocolumn]{article}.
But, when I use multicols instead twocolumns the abstract (title and contents) changes font size to smaller one.

How can I fix it?

%%%%****This is my code*****
\documentclass[10pt]{article}
\usepackage{multicol}
\setlength{\columnsep}{20.0pt}
 \title{some title}

\begin{document}
\maketitle
  %%this this title haven't the correct size    
\begin{abstract}
    this abstract haven't the correct size  
\end{abstract}
\begin{multicols}{2}


\section{introduction}%%this title have the correct size
some introduction.

Whatever, whatever, whatever, whatever, whatever, whatever, whatever, whatever, whatever, whatever, whatever, whatever, whatever, whatever, whatever, whatever, whatever, whatever, whatever, whatever, whatever, whatever, whatever, whatever, whatever, whatever, whatever, whatever, whatever, whatever, whatever, whatever, whatever, whatever.
\section{another section}
Whatever, whatever, whatever, whatever, whatever, whatever, whatever, whatever, whatever, whatever, whatever, whatever, whatever, whatever, whatever, whatever, whatever, whatever, whatever, whatever, whatever, whatever, whatever, whatever, whatever, whatever, whatever, whatever, whatever, whatever, whatever, whatever, whatever
\end{multicols}
\end{document}

Thanks.

Answer 1

Here it is.

Simply modify the meaning of abstract by inserting the following lines in your preamble:

\makeatletter
\renewenvironment{abstract}{%
    \if@twocolumn
      \section*{\abstractname}%
    \else %% <- here I've removed \small
      \begin{center}%
        {\bfseries \Large\abstractname\vspace{\z@}}%  %% <- here I've added \Large
      \end{center}%
      \quotation
    \fi}
    {\if@twocolumn\else\endquotation\fi}
\makeatother

MWE:

%%%%****This is my code*****
\documentclass[10pt]{article}
\usepackage{multicol}
\setlength{\columnsep}{20.0pt}
 \title{some title}

\makeatletter
\renewenvironment{abstract}{%
    \if@twocolumn
      \section*{\abstractname}%
    \else %% <- here I've removed \small
      \begin{center}%
        {\bfseries \Large\abstractname\vspace{\z@}}%  %% <- here I've added \Large
      \end{center}%
      \quotation
    \fi}
    {\if@twocolumn\else\endquotation\fi}
\makeatother

\begin{document}
\maketitle
  %%this this title haven't the correct size
\begin{abstract}
    this abstract have the correct size
\end{abstract}
\begin{multicols}{2}


\section{introduction}%%this title have the correct size
some introduction.

Whatever, whatever, whatever, whatever, whatever, whatever, whatever, whatever, whatever, whatever, whatever, whatever, whatever, whatever, whatever, whatever, whatever, whatever, whatever, whatever, whatever, whatever, whatever, whatever, whatever, whatever, whatever, whatever, whatever, whatever, whatever, whatever, whatever, whatever.
\section{another section}
Whatever, whatever, whatever, whatever, whatever, whatever, whatever, whatever, whatever, whatever, whatever, whatever, whatever, whatever, whatever, whatever, whatever, whatever, whatever, whatever, whatever, whatever, whatever, whatever, whatever, whatever, whatever, whatever, whatever, whatever, whatever, whatever, whatever
\end{multicols}
\end{document}

Output: