UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
WASHINGTON, D.C. 20549
 
SCHEDULE 14A
Proxy Statement Pursuant to Section 14(a) of the
Securities Exchange Act of 1934
(Amendment No.    )

Filed by the Registrant   ☒	Filed by a Party other than the Registrant   ☐	
Check the appropriate box:
☐	Preliminary Proxy Statement	
☐	Confidential, for Use of the Commission Only (as permitted by Rule 14a-6(e)(2))	
☐	Definitive Proxy Statement	
☒	Definitive Additional Materials	
☐	Soliciting Material under Rule 14a-12	
Aspen Aerogels, Inc.
(Name of Registrant as Specified In Its Charter)
(Name of Person(s) Filing Proxy Statement, if other than the Registrant)
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☐	Fee computed on table below per Exchange Act Rules 14a-6(i)(1) and 0-11.	
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- Before You Vote - How to Access the  Proxy Materials Proxy Materials Available to VIEW or RECEIVE: Annual  Report 2.  Proxy Statement How to View Online: Have the information that  is printed  in the  box marked by the arrow xxxx xxxx xxxx xxxx (located on the following page) and visit: www.proxyvote.com How  to Request and   Receive a PAPER  or E-MAIL  Copy: If you want to  receive a paper or e-mail copy of these  documents,  you must request  one. There is NO charge for requesting a copy. Please choose one of the following methods  to  make your  request: I) BY  INTERNET: www.proxyvote.com 2) BYTELEPHONE: 1-800-579-1639 3) BY E-MAIL : sendmaterial@proxyvote.com  If requesting materials by e-mail, please send a blank e-mail with the information that is printed  in the  box marked by the arrow xxxx xxxxxxxx xxxx (located on the following page) in the subject  line. Requests, instructions and other inquiries sent to this e-mail address will NOT be forwarded  to your investment advisor. Please make the request as instructed  above on or  before June 06, 2018 to facilitate timely delivery.  How To Vote -Please Choose One of the Following Voting Methods Vote In Person: Many stockholder meetings have attendance  requirements including, but not limited to, the possession of an attendance  ticket  issued by the  entity  holding the  meeting. Please check the  meeting materials for  any special requirements for meeting attendance.  At the meeting, you will need to  request a ballot to vote these shares. Vote By Internet: To vote now by Internet, go to www.proxyvote.com.  Have the information that is printed in the box marked  by the arrow  xxxx xxxx xxxx xxxx  available and follow the instructions .Vote  By Mail: You can vote by mail by requesting a paper copy of the materials, which will include a proxy card. 0000379355_2 R.1.0.1.17
 
Voting  items The Board of Directors recommends you vote FOR the following: 1.    Election of  Directors Nominees 01    Rebecca  A  Blalock 02   Robert  M .  Gervis The Board of Directors recommends you vote FOR the following proposal: 2. The ratification  of  the  appointment of KPMG LLP as Aspen Aerogels, Inc's independent registered  public accounting  firm  for  the  fiscal  year  ending  December  31 ,    2018 NOTE:   Such  other  business as  may  properly come  before  the  meeting  or  any adjournment  or  postponement  thereof. 0000379355_3 R.1.0.1.17
You can vote by mail by requesting a paper copy of the materials, which will include a proxy card. Internal Use Only

Voting items The Board of Directors recommends you vote FOR the following: 1. Election of Directors Nominees 01 Mark L. Noetzel 02 William P. Noglows The Board of Directors recommends you vote FOR the following proposal: 2. The ratification of the appointment of KPMG LLP as Aspen Aerogels, Inc.'s independent registered public accounting firm for the fiscal year ending December 31, 2019. NOTE: Such other business as may properly come before the meeting or any adjournment or postponement thereof. 0000414386_3 R1.0.1.18 BARCODE 0000 0000 0000 0000 Broadridge Internal Use Only xxxxxxxxxx xxxxxxxxxx Cusip Job # Envelope # Sequence # # of # Sequence #

Reserved for Broadridge Internal Control Information NAME THE COMPANY NAME INC. - COMMON 123,456,789,012.12345 THE COMPANY NAME INC. - CLASS A 123,456,789,012.12345 THE COMPANY NAME INC. - CLASS B 123,456,789,012.12345 THE COMPANY NAME INC. - CLASS C 123,456,789,012.12345 THE COMPANY NAME INC. - CLASS D 123,456,789,012.12345 THE COMPANY NAME INC. - CLASS E 123,456,789,012.12345 THE COMPANY NAME INC. - CLASS F 123,456,789,012.12345 THE COMPANY NAME INC. - 401 K 123,456,789,012.12345 0000414386_4 R1.0.1.18 THIS SPACE RESERVED FOR SIGNATURES IF APPLICABLE Broadridge Internal Use Only Job # Envelope # Sequence # # of # Sequence #