Sec Form 4 Filing - SCHILLING KEITH L @ ASPEN AEROGELS INC - 2022-06-02

FORM 4 Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940

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1. Name and Address of Reporting Person SCHILLING KEITH L 2. Issuer Name and Ticker or Trading Symbol ASPEN AEROGELS INC [ ASPN] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) _____ Director _____ 10% Owner X __ Officer (give title below) _____ Other (specify below) Sr. Vice President, Technology (Last) (First) (Middle) 30 FORBES ROAD, BUILDING B 3. Date of Earliest Transaction (MM/DD/YY) 06/02/2022 (Street) NORTHBOROUGH, MA01532 4. If Amendment, Date Original Filed (MM/DD/YY) 6. Individual or Joint/Group Filing (Check Applicable Line) __ X __ Form filed by One Reporting Person _____ Form filed by More than One Reporting Person (City) (State) (Zip)

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned 1.Title of Security (Instr. 3) 2. Transaction Date (MM/DD/YY) 2A. Deemed Execution Date, if any (MM/DD/YY) 3. Transaction Code (Instr. 8) 4. Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5) 5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4) 6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4) 7. Nature of Indirect Beneficial Ownership (Instr. 4) Code V Amount (A) or (D) Price Common Stock 06/02/2022 A 53,590( 1 )( 2 ) A $ 0( 1 )( 2 ) 61,433( 3 ) D

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned ( e.g. , puts, calls, warrants, options, convertible securities) 1. Title of Derivative Security (Instr. 3) 2. Conversion or Exercise Price of Derivative Security 3. Transaction Date (MM/DD/YY) 3A. Deemed Execution Date, if any (MM/DD/YY) 4. Transaction Code (Instr. 8) 5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4, and 5) 6. Date Exercisable and Expiration Date (MM/DD/YY) 7. Title and Amount of Underlying Securities (Instr. 3 and 4) 8. Price of Derivative Security (Instr. 5) 9. Number of Derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4) 10. Ownership Form of Derivative Security: Direct (D) or Indirect (I) (Instr. 4) 11. Nature of Indirect Beneficial Ownership (Instr. 4) Code V (A) (D) Date Exercisable Expiration Date Title Amount or Number of Shares

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other SCHILLING KEITH L 30 FORBES ROAD BUILDING B NORTHBOROUGH, MA01532 Sr. Vice President, Technology Signatures /s/ Poongunran Muthukumaran, Attorney-in-Fact 06/06/2022 Signature of Reporting Person Date

Explanation of Responses:

( 1 )The reporting person was granted restricted shares of common stock (the "Award") pursuant to a Performance-Based Restricted StockAgreement by and between Aspen Aerogels, Inc. and the reporting person subject to the 2014 Employee, Director and Consultant EquityIncentive Plan. In order for a tranche of this Award to vest, both time and performance vesting conditions must be satisfied. For the time vestingcondition, a tranche will vest at the later of (i) three years from the grant date or (ii) one year from the date when an applicable performancehurdle is achieved, subject to a maximum five-year vesting period for shares with respect to which the performance hurdle has been achieved.With respect to the performance vesting condition, there are three tranches with different share price hurdles and a five-year total performanceperiod. If a share price hurdle is not met after five years, the applicable tranche is forfeited. ( 2 )(cont.) The share price hurdle is met by reference to a 30-day volume weighted average price (VWAP) that is maintained for 60 days (the "Share Price Hurdle"). The first tranche consists of 34% of the restricted shares of common stock granted under the Award, with the Share Price Hurdle equal to $43.33.The second tranche consists of 33% of the restricted shares of common stock granted under the Award, with the Share Price Hurdle equal to $64.99. The third tranche consists of 33% of the restricted shares of common stock granted under the Award, with the Share Price Hurdle equal to $86.65. ( 3 )Represents 7,843 Restricted Stock Units and 53,590 Restricted Stock.

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.

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