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> ANNUAL REPORT PURSUANT TO SECTION 13 OR 15 ( d ) OF THE SECURITIES EXCHANGE ACT OF 1934 UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington , D.C. 20549 FORM 10 - K ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15 ( d ) OF THE SECURITIES EXCHANGE ACT OF 1934 No X For the fiscal year ended December 31 , 2020 or FOR THE TRANSITION PERIOD FROM NANOPHASE TECHNOLOGIES CORPORATION ( Exact name of registrant as specified in its charter ) COMMISSION FILE NUMBER 000-22333 Delaware ( State or other jurisdiction of incorporation or organization ) ΤΟ Large accelerated filer Non - accelerated filer 1319 Marquette Drive , Romeoville , Illinois 60446 ( Address of principal executive offices ) ( zip code ) Registrant's telephone number , including area code : ( 630 ) 771-6708 Securities registered pursuant to Section 12 ( b ) of the Act : None Securities registered pursuant to Section 12 ( g ) of the Act : Common Stock , par value $ .01 per share Indicate by check mark whether the registrant is a well - known seasoned issuer , as defined in Rule 405 of the Securities Act . Yes 36-3687863 Indicate by check mark if the registrant is not required to file reports pursuant to Section 13 or Section 15 ( d ) of the Act . Yes □ No ( I.R.S. Employer Identification No. ) Indicate by check mark if the registrant ( 1 ) has filed all reports required to be filed by Section 13 or 15 ( d ) of the Securities Exchange Act of 1934 during the preceding 12 months ( or for such shorter period that the registrant was required to file such reports ) , and ( 2 ) has been subject to such filing requirements for the past 90 days . Yes > No Indicate by check mark whether the registrant has submitted electronically every Interactive Data File required to be submitted pursuant to Rule 405 of Regulation S - T ( §232.405 of this chapter ) during the preceding 12 months ( or for such shorter period that the registrant was required to submit such files ) . > Yes No Indicate by check mark if disclosure of delinquent filers pursuant to Item 405 of Regulation S - K is not contained herein , and will not be contained , to the best of registrant's knowledge , in definitive proxy or information statements incorporated by reference in Part III of this Form 10 - K or any amendment to this Form 10 - K . X Accelerated filer Smaller reporting company Emerging growth company Indicate by check mark whether the registrant is a large accelerated filer , an accelerated filer , a non - accelerated filer , a smaller reporting company , or an emerging growth company . See the definitions of " large accelerated filer , " " accelerated filer , ” “ smaller reporting company , " and " emerging growth company " in Rule 12b - 2 of the Exchange Act . ( Check one ) : ■